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SPACE DYNAMIC

This document discusses the key differences between weather and climate. Weather refers to short-term atmospheric conditions, while climate describes average conditions over a longer period of 30-40 years. Weather is influenced by temperature, precipitation, humidity, pressure, winds, cloud cover, sunshine, altitude, and ocean currents. These elements are measured at weather stations. The document then goes on to describe in detail several elements of weather including temperature, atmospheric pressure, sunshine, and humidity. It discusses how each of these elements is measured and recorded, and the various factors that influence them.

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SPACE DYNAMIC WEATHER AND CLIMATE (a) Differencebetween weather and climate There is a slight differencebetweenweather and climate. Weatherrefersto as the actualstateof atmosphereand climaterefersto the averagestateof atmosphere. By definition: Weather is the conditionof the atmospherewith regard toitselements for a certainplaceand at specific moment. It is the dailyatmospheric condition of a placeat particular time. It isthe conditionof being hot, windy, cold, foggy, or cloudy. Weather changesfrom timeto timeand from place to place. The conditionof the atmosphereisdetermined by the elementsof weather which are: o Temperature o Humidity o Atmospheric pressure o Clouds o Precipitationand o Winds Climate isthe averageatmosphericconditionover a long period of time over 30 to 40 years withina specific geographicalarea. Factors that influence weather and climate Weather and climateareinfluenced by the factorslike; -Temperature -Precipitation -Humidity -Pressure
-Winds -Cloud cover -Sunshine -Altitudeand -Oceancurrents. Measuring and recording theelementsof weather and climateis done at a weather station. WEATHER STATION isa placethat is set asidefor the purpose of observing measuring and recording weather elements. Element of weather 1. TEMPERATURE Temperatureisthedegree of a heat of a body. It is a measureor degree of hotness of an object or place .Temperatureismeasured by an instrument called thermometer. Thelines joining all places with equaltemperatureare
called isothems RECORDING TEMPERATURE 1. The mean(or overage) dailytemperatureisobtained byadding thedaily maximumand the daily minimum temperatureand dividing thesum by two. 2. The daily rangeof temperatureisobtained bysubstracting thedaily maximumtemperaturebythe daily minimum temperaturewhich is, daily max temp – daily minimum temperature
3. The mean (or average) monthly temperatureisobtained bydividing the sum of daily meantemperatureofa month by thenumber of days in that particularmonth 4. The monthlyrange of temperatureisobtained bysubtractingthelowest daily temperatureofa month from the highest meandaily temperatureof that particular month. 5. The mean(or average) annualtemperatureisobtained bydividing the sum of the monthly mean temperaturesofthe particular year by12. 6. The meanannual rangeof temperatureisobtained bysubstracting the lowest mean monthly temperatureofa year from the highest meanmonthy temperatureofthat sameyear. FACTORS AFFECTING INSOLATION ORTEMPERATUREOF A PLACE Factorsthat influencethe amount of insolationreceived any point and thereforeits radiationbalanceand heat budget varyconsiderablyover time and space.Theyincludethe following. (a) Seasons and angle of incidence The earth as a planet moves along its orbit throughout theyear under this movement inclinationof the earth variesand theangle of which the sun rays strikesthe earth'ssurfacechangeswith seasons. Also thedistanceof the earth from the sun variesfrom month to month.At spring and autumnequinoxes.(21th March and 23rd September) theangleof incidenceat theequator is 90º making anarea to have high temperature throughout theyear.Temperatureisdistributed equallyinboth hemispheres.At thesummer and winter solsctice(21th Juneand 22nd December) due to earth tilting thesun is overhead at the tropicswherethe hemisphereexperiencesummer willreceive maximuminsolation.Theangle of incidenceisthe most important factor which influencestheamount of insolationof a place on theearth'ssurface.
(b)Distance from the sea There is often a considerabledifferencesbetweentemperatureofland and water surface. The reason for thisis that land surfaceheatsand cool more slowly than thesea. Due to this summer temperatureincoastalareasarelower than in continentalinterior. Likewisewinter temperaturewillbe higher in coastal areasthanin continentalinterior ifthe windsblow towardstheshore During the day and during night the situationisrelated toland and sea breeze. Areaswhose temperaturesaregreatlyaffected bythe sea are reffered to as maritime.Thegreater distancefrom thesea the colder the winter it will be and the warmer the summer develops.
(c)Altitude The rateat which temperaturedecreaseswith increasing altitudeiscalled lapse rate. Normallyair temperaturedecreaseswith increasing heightat a rateof 0.6ºc R.r 100 meters.Thisisbecausewhen earth surfaceis heated it passes itsheat on air making atmospherebeing heated from below and not directlyfrom thesun.This affect temperaturebecausethehigher you go the cooler it becomes. Altitudeexplainswhyhighlandsin the tropicsareever
cold e.g Mt. KilimanjaroinTanzania. (d) Aspect Thisrefers to the directioninwhich a slope falls.Some slopes are exposed to the sun thanothers.The atmosphereofthe north facing slopes of highlands in the northernhemispherealso called ubac arecooler than theslopes facing south adret.Thesamething appears inthe southernhemisphere (e) Latitude It is the angular distancefrom the equator tothe poles. It determinesboth the length of day throughout theyear and the intensityand possible durationof sunlight received.
As one moves pole wardsfrom theequator he experiences gradual progressivedecreaseintemperature. Thisisbecausethe sun strikesthe equator moreintensitythanit does in the poles two observations canexplainthis phenomenon. (i)At the equator thebeam of light strikethe earth'ssurfacecovering a smaller surfacearea thanin the poles wherethe same beam of light covers a larger surfacearea. (ii)At theequator thebeam of light striketravels a short distancehence experiencing lessatmospheric effectslike absorptionreflectionand scattering.At thepoles thebeam of light travels a longer distanceand it experiencesmoreeffects in the atmosphere. (f) Cloud cover The atmosphereof areascovered with heavy clouds is cooler thanthat of areaswith clear skies.Thisis because cloudsprevent insolationto reach sand sea surface. (g) Length of day and night Insolation is only received during day light hours and reachesits peakat noon .The longer the period of solar insolationthe greater thequantityof radiationreceived at a givenplace on theearth'ssurface.Thereareno
seasonal variationsat theequator wheredays and nightsareof equal length throughout theyear.In contrast polar regionsreceiveno insolation during part of winter when there is continuousdarknessbut may received up to 24 hours of insolationduring partsof the summer when the sun never sinks below the horizon .This occursin thelands of the midnight sun (f) Prevailing winds. Temperatureofthe wind is affected by the temperatureofit'sarea of origin and of the surfaceover which it blows normal windsblowing from the sea during winter warmstheatmosphereof the land near thesea while winds blowing from the sea during summer cools the atmosphereof thecoast (g)Ocean currents Warm oceancurrentscarrywarm water polewards and rise the air temperatureofthe maritimeenvironmentswheretheyfollow while cold ocean currentscarrycold water to the equator and so lower the temperatureofthe coast areas. Factors affecting the flow of ocean Currents Oceancurrents – this is the horizontalmovement of masswater in a defined direction.Themovement is due to densityvariationat various depthsgovernent by the temperatureand salinity.The meeting of two currentsconverging uponone another causessinking of water which counter balanceswith ascending masses.  Salinitydifferences Density of ocean water is caused by amount of salts the more salt in an ocean thedenser the water will be.Denser water sinks in water with low densitywhich causes the formationofocean currents.  Temperature Temperaturecausesdifferencesinwater densitywhich causesocean water to move. The cold water is denser than warm water, thistendsto make polar cold water sink to the bottom thenflow downwardstowardsthe equator whilethe warmer less denser water at the tropic moveson the
surfacetowardsthepoles .After being cooled it sinks againand moves towardstheequator hence the oceancurrent.  Prevailing winds When wind blows over oceansurfaceit pushes water surfaceand forms the ocean current .Prevailing windsthereforecausethewater to move to the directiontheyblowing to winds causedrift currents. Anexampleof drift currentsis the north Atlantic drift which iscaused by the westerly windsin the Atlantic ocean.  Rotationof the earth Thiscauses the current flow to be affected as they aredeflected or pushed according toFerrell’s law. Ferrell’s law slatesthat"Anythingmoving freely in the northernhemispherewill be deflected to itsright while in the southernhemisphereit will be indirectlythough thewinds where in the northernhemisphereoceancurrent are deflected to their right whilein the southernhemisphereto their left ".  Shapeof landmasses The flow of ocean water canalso be directed bythe landmass.Theocean currentsareturned from their straight coursebythe shape of adjacent landmassor coast line. What isa temperatureanomaly? The term temperatureanomalyis used specificallytodescribetemperature differencesfrom a mean.It shows the differencebetweenthe mean temperatureofa placeand the meantemperatureofother places with the samelatitudein thesame month. For example:Anarea which has a mean Januarytemperatureof4ºc, which is 20ºc higher thantheaveragefor other locationlaying at 58 degree latitudenorth.such anomaliesresult primaryfrom theueven heating and cooling rates of land and sea and areintensified by the horizontaltransfer of energy by oceancurrentsand prevailing winds. 2. ATMOSPHERIC PRESSURE Air has weight and therefore it exertsthe pressurecalled atmospheric pressureon the earth surface.Pressurevarieswith thetemperatureand
altitude, and an instrument which measurepressureiscalled barometer. There aretwo types of mercury (i)barometer (ii)aneroid barometer The lines which join all placeswith equal pressureare called bars.Thus pressurevaries from one place to another it is not the same in one or all the regions. FACTOR INFLUENCINGVARIATION IN ATMOSPHERIC PRESSURE  Temperature As temperaturedecreasepressurerisesat the sameheight due to low temperaturecold air tend to sink, thus inducing high pressuretodevelop But as temperatureincreaseshot air tendsto rise making it possible for low pressureto develop over thearea.  Altitude Usually pressureof the atmospheredecreasewith increasing height. Pressureis therefore lower at the mountaintop thanat thesea level.This is becauseat the sea level air hasto support a greater height thanit does on the top of mountain.Thusthereisless force or weight of air at the mountain top thanat the sea level.
 Revoluationof the Earth The earth revolutioncausesseasons wheresome seasons arewarm while others arecold .Revolution of the earth affectsthe positionof the low pressurebelt i.e doldrum. Normally doldrum moves northwardsand southwardsof the equator depending onthe seasons. Earth rotation asa ball causesformationof subtropicalhigh-pressurebelt around 35º north and south of the equator whereair sinks down and gets compressed .Due to thiscompressionthe sinking of air is heated up and rises again. Thesame situationtakesplacearound circumpolar or temperaturebelt around 60º north and south of the equator.Thesearethe areaswhere the warm subtropicalair risesover the cold polar air expands and getscooler.Thissituationresult intoDepression cyclonic or frontal. PLANETARY PRESSURE BELTS THE WORLD PRESSURE BELTS These canbe analyzed according totemperatures: (i)Equatoriallow pressure belt / equatorinallytrough Thisis called doldrum it is located around 5º north and south of the equator.Theair hererises due to high temperatureit isa wind a convergencezone. This meanswinds meet there and it is called intertropicalconvergencezone (ITCZ) (ii)Subtropichigh pressurebelt (Horse latitudes) Thisis located at 30º north and south of the equator with descending air current due to heat of temperature. High pressureis attributedby accumulationofcold air which moves from the equator towards poles.This belt is also referred to as the"horse belt". (iii)Temperaturelow pressure belt (sub polar low temperaturebelts) Thisis found at 60º north and south of the equator. It is also known as cyclonic activities zoneor zone of convergence. Existanceoflow pressureis mainlydynamic rather thana result of temperaturechange.
(iv) Polar high-pressurebelt Thisis confined at 90º north and south of the equator. Pressureis permanentlyhigh due to low temperatureattributed bya dense descending air from the temperaturelow pressure belt. 3. SUNSHINE Thisis another element of weather. The durationofsunshine is partyof a functionof latitude. For the hours of light (that ispossible sunshine) vary with these season in different latitudes.It is also a functionof daytime cloudiness . MEASUREMENT ANDRECORDING OF SUNSHINE The durationof bright sunshineismeasured by means of campbellstokes recorder, a solid sphere of glass 10cm in diameter. Thisform the rays of sunshine onto a sensitized card graduatedinhours and so burn a line during thetimethe sun is shinning .Faint sun,light sun, near dawn or dusk or when the sun is partiallyabscured isnot recorded .Tables of sunshine
data areprepared from these record, in the form of either absolutesolution in hours per day or as percentageofpossible sunshine per dayor month. When meansfigureshas been obtained over the requisitenumber ofyears, the value for each statecanbe plotted, and lines of equal meandurationof sunshine isohels can be interpolated. 4. HUMIDITY Thisis refered to as the atmospheric moister.Themoister is obtained from varioussources such as oceans, lakes,seas, dams,pondsand rivers. It is of high importanceasfar as weather as climateisconcerned. Air absorbs water through theprocess of evaparationwhich result in water changing from itsliquid stateto gaseousstate,thegaseousstateis called water vapour. The amount of water vapour in the air is called humidityand it is measured by an instrument called hydrometer placed inthe Stevenson screen.
FACTOR INFLUENCINGHUMIDITY -Air pressure When air is compressed, it warmsup and its densitybecomeslower .Thus at low altitudewherepressureis high air will absorb more moister. At high altitudewherepressureis lower air expandsand cools and itscapacityto absorb moister isreduced. -Latitude Humidityhigher inlower latitudesthaninhigher latitudebecausethere is greater rateof evaporationat lower latitudesdue to high temperature.Likewisethemount of moister in the air is higher in summer . -Temperature Arisein temperaturelowersrelativehumidityifthe amount of moister remainsconstant becausewhenair is heated it expands.Thevolume
increaseand therefore distributionofwater vapour per unit.Volume becameless.The air will have a greater capacityof holding more water vapour if air is cooled it contractsand decreaseinvolume making thespace which moister canoccupybecomeless .That is why if air continuesto cool it will reach saturationand it getsrid of excess water vapour through condensation. -Moisturesupply If the supply of moistureincreasestheair will have moreof it ,they making absolutehumiditytobehigher .If the temperatureiftheair increasesit will absorb even more moisture.Thissituationmakesallplaces which are near large water bodiesto be humid especiallyif the temperature is high causing a lot of evaporation. Areasthat arefar awayfrom large water bodiessuch as desertscenter has little water vapour the air has high capacityof holding moisture. IMPORTANCE OF WATER VAPOUR IN THE ATMOSPHERE - Evaporationformsprecipitation,which providesfresh water plantsand animals. - It absorbsboth incoming and radiated energyfrom the sun. - It conveys Latent heat into the atmosphere The amount of water vapour the atmospherecanhold depends upon the temperatureofthe air thehigher the temperatureofthe air the higher the capacityof it to hold water . COMMON WAYS OF STATING WATER VAPOUR (HUMIDITY ) (I) Absolutehumidity Thisis theactualamount of water vapour in a specific volume of atmosphere i.ethe massof water vapour per cubic unit of air and it is normally expressed in g/m3 (II) Relative humidity Thisis theproportionof water vapour present in the air compared tothe maximumamount ofwater vapour, possible at the same temperatureand it is usually expressed in percentage.Normallysaturated air hasrelative humidity100%. 5. PRECIPITATION
Thisrefers to water that falls on the earth in liquid or solid forms.Some commonforms of precipitationarerain, snow, sleet and hail. Rain Thisis most commonform of precipitationspread everywhere and it is liquid form.It forms when tiny water dropletsmergetogether around the nuclei to form raindrops.After becoming heavyenough they fall down to the earth surfaceas rain.Rainfallismeasured by an instrument called rain gaugeand the lines which joinall placeswith equal rainfallare called isohyets. Snow Thisis refered to as solid precipitation, which formswhenair cools to below the dew point or freezing point and fall down as icewhile falling the icecrystals mayjoin together toform snow flake. Sleet Thisis a frozen or partly frozen raindroplet; it so often referred to as frozen rain. It is hazardousas it maydestroy crops, bring down power lines and tree branches Hail Thisis caused by super cooling of water particlesina convectionalup shaft .This super cooling formsthe hail stones .These stone vary in size depending on the intensityof cooling by that convectionalcewent. It is more hazardousthansleet. Hail can causecoderabledamagetoproperty and plantssome hail stones weight up to 2.5 Kilogram which mayhit the ground at speed of up to 160 km/hr. All forms of precipitationresult from rising and cooling of air to below the dew point where condensationbegins.Thevisibleeffect here is clouds in order for precipitationtooccur the small dropletsof water in clouds must join together indrops too largeto remainor be sustained in theatmosphere thus they prefer to fall down on the earth surfaceasprecipitation.
CAUSES OF RISING OF AIR When air risesthere is less pressureon it at the new altitude.Asa result the temperatureofthe rising air islowered and cools causing that air to descend and becomewarm. The rateof cooling or heating that resultsfrom thisverticalmovement of air (ascending deslending) is called adiabatic rate. For saturated air therateof temperaturechangeis0.6ºc per 100 meters, which forms unsaturatedair rateis1ºc per 100 metersand it is called dry adiabaticrate. CAUSES OF AIR RISING FOR PRECIPITATION The causesof air rising arealso known as the types of rainfall or the factors that influencerainfall. The factorsincluderelief convectionand the water bodies. (i) Orographic or reliefcause Orographic causeofair rising forms orographicor relief rainfall.It forms when air is forced to ascend as a result of relief featuressuch as mountains or plateaus. Wheremoist air reachesthe mountainprecipitationformsand it is called windward sidewhile the other passaway from windward form the leeward side or rainshadow.
When moist air is forced to rise over a mountainrange,cloudsand rain often occur. (ii) convectionalcause Here air is forced to rise as a result of intense heating thesurfaceair is heated and verticalupshaft toair occur thisprocess is called convectionand it forms convectionalrainsit is common in summer or hot seasons.
(iii) Frontal or cyclonic cause Wheretwo bodiesof air masses coming from different directionsand with different characteristicsintermsof temperatureand moisturecontent meet, the warmer air will be forced to rise and condense to form precipitation. Thepoint where these two windsor air meet is called front hence frontalof cyclonic rainfall.
Warm air isforced to rise when it is under cut by colder air,cloudsand sometimesRain. Importanceof precipitation i. It maylower temperature ii. It supplieswater to streamsand rivers iii. It is a sourceof water watering crops iv. It absorbssolar radiations IMPACTS OF PRECIPITATION. Impactsof precipitationcanbecategorized intopositiveand negative. (i) Development of water bodies: precipitationencouragesthe development of water bodiessuch as rivers and lakes. These areimportant for irrigation, hydroelectricpower generation,transport, supplyof H2O for domestic and industrialuseand fishing.
(ii) Cleaning the atmosphere. Thefalling drops collect the dust particles and deposit them on thesurface, keeping the atmospherecleanor less polluted. (iii) Temperatureregulation: -precipitationespeciallyrainfall, regulatesthe temperaturesuch that theatmosphereattainsmoderateweather condition rather thanextremes. (iv) Soil development precipitationalsoplays an instrumentalrolein soil development. It encouragestheweathering of rocksand the decomposition of organic matter. Wherethereis high precipitationchemical decompositiontakesplaceeffectively. (v) Encouraging plant growth: precipitationsupplieswater thesurface, which used by plant for growth. Thishas advantageinthe development of Agriculturesincewhereis effectiveplant growth there is positive agriculturaldevelopment. (vi)Soil erosion:thistakesplacewhen rainfall is very heavy. Erosion is more pronounced in the areaswhere the surfaceis bareand sloppy Erosion destroys vegetation, houses, transport systemsetc. (vii) Outbreakof diseases:when thereis precipitationwater borndisease such as dysentery. Typhoid, diarrhea and cholera, aswell malaria arevery common (viii) Floods: Heavy precipitationleadsto theoccurrenceof floods, which in turndestroy crops, houses,kill animalsand people etc.
(ix) Mass – wasting (massmovement) takes placeas result of the disturbancescaused byprecipitationon the weathered rock particles. Mass movement can destroycrops, kill people and animalsand destroy electricity supply networks as well as causing a lot of damage. (x) Water pollutionis caused by surfacerun – off cover land Flow and foods, which collect variouswaste materialsand emptythem in the water bodieslike rivers. Dams and naturallakes. Some of thepollutants are deleteriouscharmatultohumanhealth. 6. WINDS A wind is air in motionwhich alwaysmove from high pressureto low pressure belts.Wind speed is measured by an instrument called anemometer whilewind directionismeasured bywind vane. During wind movement it causessome balancessuch as temperaturebalance, humidity balanceand pressure balance. FACTORS WHICH ACCOUNT FOR DIRECTION AND STRENGTHOF WIND 1. Pressuregradient
Variationof pressurefrom one place to another due to variationinpressure causeswind to develop and move from high – pressurebelt to low- pressurebelt: the larger the pressuregradient thegreater the winds speed. 2. Coriolis force Thisis theforce due to earth rotation: It obeys theFerrell's law which state that"Anyobject moving freely in the northernhemisphereis deflected to its right whilesouthern hemisphereis deflected to itsleft". Thisforce is called Coriolis forceand the resultant wind is called geostrophic wind. 3. Friction Thisis commonespeciallyup to 900 metersabove the sea level due to mountainsand big valleys, which may reducethe speed and changethe directionof winds. The influence of frictionstronger on sand surfacethan on water. 4. centrifugalforce Thisis theforce due to earth curvatureand thisforce actsoutward whenan air stream moves on a curved courseas in a pressure system with closed or curved isobarsis subjected tocentrifugalforceacting outwardsfrom the center of curvature. WINDSYSTEMS Wind systems arerelated to pressurebelts these windsare called prevailing winds and they are deflected according toferrell's law prevailing windsare those which blow more frequentlythan other wind in a particular region. Among these winds aretradewinds westerly and polar. (i)Tradewinds These winds meet at the doldrum they arenoted for their constancyof force and direction.Theyareterribletropical stormswhich occur at certain season. At the equatorialbelt the air is heated and rises to be replaced by air moving in (winds) from north and south.Theseform north east trade
winds and south east tradewinds which obey ferrell's law. (ii)Westerlywinds These blow acrosslatitude35º and 60º to the polar front these winds are characterized byconstant strength and directioninthesouthern hemispherewhile in thenorthern hemisphereand masses disrupt much of their strength .These windsinclude north west and south west westerly (iii)Polar winds These winds areof solid air they are morepronounced in the southern hemisphereand irregular inthe northernhemispheredue to interruption by mountains. (iv)Monsoon winds These are seasonal windsif the pressureof a largecontinent is high the wind will blow out of it to the sea where pressureis low These arecalled ''offshore winds". These winds arecommonduring winter in Asia as inland temperatureis very low while sea temperatureisstill warm and less dense.If the pressure over a largecontinent is low thanwindsblow intoit from the sea where pressureis higher.Thesewindsare called "onsharewinds" and they are commonin Asia during summer. (v)The upper air movement Prevailing windsarenormally surfacewinds not very far from the earth's surface. These systems of wind are of high speed and high altitude approximately1000 to12000 metersabovethe sea level withinthese winds are narrow bandsof extremelyfast moving air known as "jet streams" JET STREAMS Evidences of strong windsin the upper tropospherefirst camewhen first world war, several interwar ballonsblown off- coursewere observed
travelling at speed in eccess of 200 km per hour. Pilots in thesecond world war, flying at height above8km found east ward flightsmuch faster and their returnwestward journeymuch slower thanexpected. Theexplanation was to and to be a belt of upper air westernizesthe Rossby wave which form a computepatternaround theglobe. FIVE MAIN JET STREAMS ARE There arefive recognizablejet streams, twoareparticularlysignificantwith a third having seasonal importance i. Polar front jet stream (PEJS) Thisoccursin middle latitudesbetween40 and 60 degreesand a height of 9000 – 12000 meter moreor less at the tropopauseinthe hemisphere. The winds form the divisionbetween theferrell's and polar cells which is the boundarybetweenwarm tropicaland cold polar air these winds are responsiblefor giving fine or wet weather on the earth'ssurface. ii) Sub tropicalset stream (STJS) Thisoccursat about 12000 metersand 25 to 30 degreesfrom the equator and form the boundarybetweenthe Hadley and Ferrell cell in effect vortex associated with themid-latitudecell. They have lower velocitycompared to PFJS but follow thewest-east pattern. iii) EquatorialEasterliesset stream (EEJS) Thisis moreseasonal being associated with thesummer monsoon of the Indiansub continent. iv) Arctic set streams(AJS) Thishas been traced acrossAlaska and Canada at about 7600 meters. v) Polar night set stream (PNJS). Thisis recentlydiscovered above the Aretic circleinthe lower Stratosphere.
LOCAL WINDS. Local winds arecontrolled by the surrounded”terrain”or environment they are not controlled by planetary system of thewinds they are rather diurnal thanseasonal. There windsdo affect animals, plantsand movement of industrialpollutants. LOCAL WINDS INCLUDE THE FOLLOWING 1) Anabatic and Katabatic i) Anabatatic winds These are cold local windswhich blow from, the valley buttonup to the hilltops. They blow in the afternoonespecially in summer. During the day
the slopes exruince. Low pressuredue to direct sun rays which makethem hot and windsmove from buttonupwards. They further condense and come down causing thebecomefoggy. There winds are called Anabatic winds. ii)Katabatic winds. These are cold local windswhich blow down from hilltops they occur during thenight where air is rapidlycooled by terrestrialradiationonthe upper slopes. During the night thevalley slopes becomevery cold as they lose the heat rapidly, hence high pressure on them. Due to convectional currentsthevalley buttom becomeswarm creating low pressure. Winds sink down through the valley slopes and rise up from thevalley buttom . These winds arecalled Katabolic winds.
2) Land and sea braze. During the day land becomeswarm morerapidlythanthe sea. Thus winds tend to move from the sea breeze. During the night theland cools more rapidlythansea. Thus wind tends to move from land to the sea thisactionis called land breeze. Day
3) Descending winds: These winds aremostly warm and they arecalled Fohn. The nameFohn is
commonin Alps Mountainsof Switzerland.Whereduring winter theFohn winds descend from the SwissAlps into Switzerland.  During the sameperiod cold winds blow from Francesouth ward torwardsMediterraneanSea. These windsare called "Mistral" but in USA thesame winds arecalled "chinook". Thissituationoccurs mostly in the leeward side of the mountain. Somelocal windsblow from the high pressureover the Sahara duringspring. Thesewinds are warm, dustyand dry becausethey originatefrom thedesert which is dry. The Harmattan. These are NE windswhich blow from the Sahara acrossWest Africa betweenNovember and March. Thesewinds aredry and dusty becausethey originatefrom thedesert. The windsblow during winter towardstheGulf of Guinea where theland is cold while over Mediterraneansea pressureis low becausethe sea is much warmer thantheland. Berg winds: These are thewinds which originatefrom theplateau of South Africa during winter. At thistimethe high pressure lies over the plateau and it is a regionof descending air the windsblow out toward the South SE and SW.Thosewindsare warmer 4) Adiabatic cooling and warming:
Thisis thechangeof heat per unit area. It occurswhen air is heated on the ground which makes it to rise as it raisesit becomescool and sinks down. Thisis adiabatic cooling and heating. AIR MASSES Air mass is a largevolume .of air whose temperatureand humidityare fairly uniform and covers all extensiveareassuch as desert and ocean surfacesmoving horizontally at different levels. - Characteristicsofair mass normally comefrom the regionwhere the air masses were formed. These characteristicsareretained bytheair mass may be warm, dry or moist. CLASSIFICATION OF AIR MASSES. Air masses areclassified on thebasisof the sourceregions trajectryand characteristicsof both temperatureand humidity. Onthe basisof temperaturetheycanbe categorized aspolar and tropicalair masses. By combining temperatureand humidityfour maincategoriescanbe distinguished asfollows. i)Tropical continental.(Tc or CT). They originateover the continentsin the low latitudessuch as in the desert. They tend to be warm and dry. But near the equatorialthereistropical equatorialcontinentalair mass, which consistsreasonableamount of moisture. Enough to cause precipitation. A good exampleis tropical continentalair massover the Sahara desert, which iscalled the Harmattan. ii) Tropical maritime (Tm or mT). These originateinthe tradewind belts and subtropicaloceansnear the equator theyare refered to as Equatorialair masses(E) these arewarm and moist such that theyto yield heavy precipitation, thunderstormsetc becauseof being unstable. A good exampleis tropicalmaritimeair masses which originatefrom Atlantic
iii)Polar continental (Pc or cP): These originatefrom thecold land surfacelike the Arctic and Antarctic regions, including centralAsia,northernCanadawherethey develop in winter. These air masses arevery cold, dry and stablesuch that they prevent theformationof rainshowers. iv)Polar maritime (Pm or mP). These originateover the oceans 50º North and south of the equator they are cool, moist and unstable. They yield heavy precipitationastheymove in land in middlelatitudesand high latitudes. CYCLONES,ANTICYCLONESAND DEPRESSIONS i) What areweather cyclones, anticyclonesand depressions? ii) Explain theFormationof these aspects iii) Explainthe weather associated with them. CYCLONES These are areasof Low- pressuresystem, which originatesontemperature Latitudebetween200 -600 north and south of the equator cyclonesoccur all over theoceans except in northernAtlantic ocean. Theisobarsthat represent a cyclone on a map areclosely spaced and they form a circular shape. Strong wind spiralsor tends to move towardsthe center clockwisein the southernhemisphereand anticlockwiseinthenorthernhemisphere. They also tend to rush upward with strong force called vortex which surround the center of the cynodes. IMPORTANCE OF CYCLONES: The rapid rising air givesto torrentialrainfalland the strong blowing wind causesconsiderabledamagetopropertysuch as crops and buildings. FORMATION OF CYCLONES.(Requiredconditions)
i) Abundant sourceof warm moist air of temperatureabout 27ºc tothesea surface ii) Air must blow in ward and riserapidlyto great height to giveclouds of great verticalextent, capableofproviding torrentialrainfall. - A Tropicalcyclonedevelops wherethe air mass brought byto northern and southerntradewindsmeet that is along the inter – tropicalfront. They form; over the oceans as theair masses which have traveled over the oceans have warm moist lower air while the upper layer of air masses tends to be cool and dry. When two such air masses meet one is lifted up over the other the rising air cools its moisturecondensesto provide rainfall(torrential). Tropicalcyclonesmove in a westerly directiononreaching laid they graduallydie act becausethesupply of warm moist air is cut off. Warm sea surfaceof temperature27ºc WEATHER ASSOCIATED WITH TROPICAL CYCLONES Before thetropicalcyclones arrive i)Air becomesvery still ii) Temperatureand humidityrises. iii) Thickcloudsappear or develop
iv) Windsblow violently v) Dense clouds and torrentialrainfallreducesvisibilitytoa few meters Examplesof tropicalCyclones aretornadoes, Hurricanesand typhoons. TORNADO Thisis a small cyclone that appearsasa blackfunnel cloud, hanging from high clouds. Its color is a result of themoistureand debrisbeing carried by wind at a speed of up to 400km/ hr on the ground. It covers a small area of about 90 – 500 metersin diameters - The originmechanism of tornadoesis not properlyunderstood however they are commonlyand mostly associated with theconditionprovided by the meeting of cold, dry and hot moist air. - Thus they are associated with cold front originatedwhereturbulence along therefronts is greatest. Most occur in the USA and are concentrated in the centralstateof OKLAHOMA. HURRICANES These occur in West Indies islands in the Caribbean. Thewind is generally very slow. They have similar characteristicswith typhoonsbut the only differenceis intensitydurationand locality - Weather associated with hurricanes: .Calm dense clouds and stormyweather . Rainless/ dry weather. TYPHOONS: Typhoons occur in China. They are most frequent from July to October and violence is common.
They have very steep gradient and cover an area of 30 to 300 kilometersin diameter. Theyoccur around 20o- 60o north and south of the equator. - Weather associated with typhoons  Over cast sky  Torrentialrainaccompanied bythunder and lighting  Verydestructive toboth humanand property. For example 50000 people were killed in 1922 on thecoast of china. ANTICYCLONE Thisis an area of high pressure which when shown on the isoline map, has an oval circular shapeofclosed isobar. Notethat, the highest pressureis near the centre. An anticyclonedevelops in a regionwhere the air is descending and the winds associatedwith it blow outwardsin a clockwise directionintheNorthernhemisphereand anticlockwiseinthesouthern hemispherein West Africa during thedry season anticyclonecover the Sahara and theyare associated with the Harmattan. WEATHER CONDITION ASSOCIATED WITH ANTICYCLONES. Anticyclonesareassociated with thefire weather, calm air and high temperatureinsummer but low in winter and clear skies. During winter intense cooling of the lower atmospheremayresults in thickFog. DEPRESSION These are largeareas of low pressuredue to meeting of warm equatorial and cold polar air. They areoval or circular shared on mapswith closed isobars. Air of depressioncirculatesanticlockwisedirectioninthe Northern hemisphereand a clockwisein the southern hemispherewherethey blow towardsthecenter. - Depressions mainlydevelop in temperaturelatitudeswhenhumid tropicalair meetswith cold polar air especially around; latitude60º north and south of the equator wherewesterly winds meet with polar winds. The
zone or boundarywhere these windsmeet or converge is called "polar front” it is in thiszone where depressionsform. - Depression arerarely stationaryand theymove in a generale.g. sterly direction. Somearesmall: others arelarge, but all of them are associated with unsettled weather usually with overcast skies and periodsof continuousrain. - The rain is caused by the uplifting ofthe warm moist tropicalair bythe cool drier polar air, as they meet or converge at the polar front. Such rainis called “depressionRain" and it is generally lighter thanconvectionalrain and has longer durationup to several days. WEATHER ASSOCIATED WITH DEPRESSION. Depressions areassociated with clear sky except the circuscloudswhich are little bit high, winds blow from the south east, after a definitetime, a clouds cover develops and heavy rainoccursand the warm front then passes, when the rainstops wind directionchangesand start blowing from south west. Temperaturerisesand thereoccursmore humid air. HYDROLOGICAL CYCLE (WATER CYCLE)
Hydrologicalcycle (water cycle) refers to the endless circulationofwater from the surface(rivers, lakes, oceansand vegetation) intothe atmosphere through evaporationor transpirationand thenbackto the surfaceasrain, snow, hail or another form of precipitation. Theprocessesinvolved in hydrologicalincludeevaporationor transpirationcondensationafter cooling and later precipitationthecombined processof evaporationand transpirationisknown as evapo –transportation At first water, getsinto theatmosphereas water vapour through evaporationfrom the surfaceor transpirationfrom parts. Later as most air rises, it cools through expansion, leading tocondunsation through condensationwater dropletsor dropsare formed which later fall onto the surfaceas precipitation. Aswaterfallsonto the surface, some of the water in filtratesand percolatesintothe ground to form underground water. Someflow on the surfaceas surfacerun – off (overland flow) or stream flow into the oceansor lakes. Someis evaporated backintothe atmospheretodrive forth the process of hydrologicalcycle. In the process of hydrologicalcycle,insolationis very important sinceit providesthe energy that facilitatesevaporationprocess.
The diagram aboveshowsthe process which lead to theformationof precipitationwhich arepart and parcelof the hydrologicalcycle. These processes includeevaporationor evapo-transpirationcooling condensation and precipitation CONDENSATION. Condensationis the processthrough which the atmosphericwater vapor is converted into liquid asa result of cooling. If the temperatureisbelow the freezing point condensationcanbe skipped.Theprocessin which water vapor changesdirectlyintosolid statewithout passing through liquid state is called "sublimation". Theterm also applied when the changetakesplace from solid stateto water vapor without passing through theliquid state when the temperatureareextremelyhigh. WAYS IN WHICH AIR COOLS:
There areseveral waysthrough which cooling in theair takes placeand these canbe identified asfollows. i)Directionradiationofheat energy from the surfaceleads to the cooling of the air, since heat energy is lost into the atmosphere. Theloss of heat energy makesthe surfacebecomecold hence influences the temperatureof air above it. ii)Horizontalair movement over the cold surface(advection) mayalso lead to the cooling effect. iii) Also cooling cantake placewhen warm air mass meetswith cold air mass on mixing along the the front,thetemperatureofwarm air declines, leading to cooling. iv)Another way through which air tendsto cool is by the ascent.The ascending air cools adiabaticallyasresult air massexpension. CONDITION FOR CONDENSATION TO OCCUR Condensationis determined byseveral factorsthat includecooling, presenceof microscopic particlesand presenceof water vapor. i)Atmosphericcooling. The cooling of the atmosphereoccursthrough variouswayswhich include contact with thecold surfacesmixing ofair masses or through mechanical uplift. ii)Existenceofwater vapor When the air saturated, anyadditionalmoistureintheatmosphereleadsto Condensation. iii)Presenceeof microscopicparticlesinthe atmosphere. Theseact as condensationnuclei which providethe starting point for condensation. Water vapor molecules tend to collect around the particlestoform water droplets when the particlesareabsent, condensationtakesplacewith difficultyunless the atmosphereissuper saturated.
COMMON FORMSOF CONDENSATION. Condensationmanifestsinvarious form namely  Dew  Frost  Clouds  Fog. Dew Dew consists of water dropletscondensed and deposited on the cold solid surfaces. It usually Forms during long nightswith clear skies having little or no wind when the atmosphereisrelatively moist.Whenthesky is clear there occurshigh rateof outgoing radiation, which inturnleads to the cooling of surface. Frost Is the term used of meandew that becomesfrozen. The conditionthat favor itsformationarethe same those. For formationof dew except the condensationoccursunder freezing point.Desert and semi-desertsare places wheredew and frost commonoccursat night, since these areascan sometimesexperiencelow night temperatureaslow below O0C. Log and mist,Haze. Fog and mist areclouds at ground level, which result from moisture condensationand they may extend far in the atmosphere.Fofand Mist differ in visibility. Mist forms wheremoist air cools below dew point. Condensationtakes placebut theresultant water dropletsremainsuspended in kilometers. On the other hand Fog is like mist and forms in the sameway but it is much denser as it reduces visibilitytoless thana kilometer. There arevarious types of fog depending on their mode of formation. TYPES OF FOG i)Advection Fog: Refers to Fog caused by the cooling of warm moist air. Transported over the
cold surface. Also, advectionFog can be caused by the cold air passing over a warmer sea surfacethan mixeswith thewarm air prevailing there. ii)Radiation Fog Thisoccurswhen land surfaceis suddenly cooled by radiationwheretheair upon it becomes chilled which results into condensation. It commonin hilly areas. iii)FrontalFog Thisforms due to passageof warm air over cold air. The warm air is thereforechilled to form Fog.It forms at the Front of depression. iv)Upslopeor expansion Fog chill Fog Refers to the Fog formed when the air-massmoves upslope leading to adiabaticcooling due to air mass expansion. It forms simplelow sheet cloud which mayenvelop the hills like, what happenson the hills of western. Britainwhenmoist air is moving on land v) Steam Fog Is the type advectionFog formed when a cold air- mass passesover much warmer water surfacesuch that water appearsto"steam" In latitudeit is referred to as ice-Fog. Wherethe moistureinthe air is converted into ice crystals, steam Fog is rare and does not last for a long period of time. vi)Sea Fog Is formed when thesea air cools over thecold ocean currents. It differs from the steam Fog,inthat the sea Fog does not appear assteam but just as normalFog. Also in steam Fog, themoving air is cold and stableand warms over thewarm water surface. vii)Smog Fog Thisis Fog plus smoke and industrialpollutant likeCO2, CO and SO2 it is usually yellowish in color and acidic insmell,smog is commonin big cities e.g. Ruhr industrialarea inGermany. Fog has major environmentalhazards particularlyon transportation. viii)Rime When a Fog composed of super cooled droplets is driven by slight wind against prominent objectssuch astelegraph poles, wiresand treesthe drops freeze on them as rime. The temperatureofboth droplets and the
objectsis below freezing point. The rimehasthe white, opaque appearance. Thisis a commonfeatureon the mountainsof Britain. CLOUDSAND CLOUDSFORMATION Cloud is another element of weather. It is defined as a mass of water vapour which hangsin the sky. Clouds are a form of condensationwhich consistsof water dropletsor of tiny icebar tidesfloating at various levels from the ground to the very high altitudes. At 12000m abovethesea level. - Mist and Fog aremade of water dropletsand in this repast theyare types of cloud, but they form near the surface. - The clouds give hint on thetype of weather that islikely to occur through their shape, height and and natureof movement. Thus they are carefully studied by meteorologistsinorder to prepareweather forecast and variousprecautionaryinformationonthe impeding weather phenomena. On the map cloud cover can be represented by using the lines. CLASSIFICATION OF CLOUDS There aremany different types of clouds, but they areoften difficult to distinguish astheyform constantlychanges. The general classificationof clouds was proposed by LUKE HOWARD in 1803 this classificationis based on form appearanceand height and he used four Latin words cirrus, cumulus, stratus and nimbus. - High clouds (6,000 to12,000m) - Middleclouds (2,100 to 6,000m) - Low clouds (below 2,100m) a) High clouds 6,000 – 1,200m (consistsof cirruswhich start with cirro.) i) Cirrusis composed of small icecrystals, wispy, fibrousor feather. Its a appearanceisminbandsor patches.
ii) Cirrocumulus –is composed of ice crystals:” globular or ripplelike in appearancelookslike ripplesor wavy structuresinthe sand on a sea shore) Forming a thincloud. iii) Cirrostratus- it looks like a thinwhite, almost transparentsheet that gives the sun and moon haloes. b) Middleclouds below 2,100 - 6,000m (consistsof clouds whose names start wish acto) i) Altocumulus – is composed of water dropletsin layers or patches globular or bumpy. Looking with Flattened based arranged inline or waves. Thisindicatesfair weather. ii) Altostratus –is composed of water dropletsforming sheets of grey or water looking clouds, partlyor totally covering the sky. c) Low clouds below 2100m. i) Stratocumulus: isa largeglobular mass: bumpy – looking soft and grey in appearanceforming pronouncesregular patten. It is in fact darker, lower and a heavier type of actocumuluscloud. It always allows the penetrationofsome our rayscalled crepuscular rays. ii) Stratus –is fog- like low cloud forming a uniform layer: brings dull weather and often carom paled by drizzle. iii) Nimbostratus –Darkgrey and rainy – looking dense and shape less often gives continuousrainclouds of great verticalextent. iv) Cumulus: round topped and flat based forming a whitish grey globular mass consisting ofindividualcloud units. v) Cumulonimbus – is a lowering cloud which is usually whiteor blackappearing as globular masswhose rounded tops often spread out forming an anvil structure. It is associated with convectionrainlightingand thunder. This cloud is sometimescalled "thunder head".
NB: Cirrusand curriform cloudsoccupyhigh level and form high clouds; clouds that start with actoarefound in the middlelevel constituting middle clouds. Nimbusisthe term that appliesto rainbearing clouds; stratus appliesto clouds that form layers or uniform cover and cumulusis the term used for clouds that occur in a massivenature. Clouds at different levels and extent
The Amount of cloud cover is estimated inoktas; one oktasrepresents one – eighth of the sky covered with clouds. WEATHER CHANGES ATMOSPHERIC STABILITY AND INSTABILITY Atmospheric stability The stateof stabilityiswhen a rising parcelof unsaturated air coolsmore rapidlythanthe air surrounding it. If thereis nothing to force the parcelof air to rise such as mountainsor fronts it will sink backto itsstarting points. The air is described asstablebecausedew point may not have been reached and the only clouds which might havedeveloped would show flat topped cumuluswhich do not produceprecipitation. Stabilityisoften linked with anticyclones. - Absolutely stableis experienced whenthe ELR is less than theSALR (SaturatedAdiabaticLapseRate). During absolutestabilityeven the saturated air, which isusually buoyant (light), tends to cool faster that the surrounding air and keeps on sinking rather thanrising. Stabilityisalso called stableEquilibrium. Atmospheric instability: Conditionsof instabilityariseinon hot days when localized heating of the ground warmsthe adjacent air byconductioncreating,ahigher lapserate. The resultant parcelof rising unsaturated air coolsless rapidlythanthe surrounding air. In thiscase the environmentallapse ratelies to the left of the Dry Adiabatic LapseRate, therising air remainswarmer and lighter thanthe surrounding air. Should it be sufficientlymoist and if dew point is reached, then the upward movement may be accelerated toproducetowering cumulusor cumulonimbustypeclouds. Thunderstormsarelikely and saturated air following the release of latent heat,willcool at the saturated Adiabatic lapse rate. CONDITIONAL INSTABILITY. Thistype of instabilityoccurswhentheELR is Lower thanthe DALR but higher thanthe SALR. It is the most commonof the three conditions.
The rising air is stablein its lower layers and being cooler thanthe surrounding air would normally sink backagain. However if themechanism which initiallytriggered theup lift remains, then the air will be cooled to its dew point. Beyond thispoint cooling a slower SALR and the parcelmaybecome warmer thanthesurrounding air. It will now continue to raisefreely even if the uplifting mechanismis removed as it is now in an unstablestate. Instabilityisconditionaluponthe air being forced to risein the first place, and later becoming saturated sothat condensationoccurs. Theassociated weather is usually fine in areasat altitudesbelow condensationlevel but clouds and showery in those above. - What tonote is that Unstableair mass is regarded tobe either conditionalor potential.It canbe conditionalifafter it has reached dew point it cools very slowly to retain warmnessthat the surrounding and forced to rise higher and higher. - It is regarded tobe potentialifthe conditionair is forced to rise above cold air mass. Atmosphericinstabilityisassociatedwith relativefall in temperature, high humidity(dampness) heavyclouds, sand, heavy rainfall. These conditionscanbe summarized asfollows: Stabilitywhen ELR< DALR or (DALR> ELR) Absolutestabilitywhen ELR< SALR or (SALR >ELR) NeutralEquilibrium when ELR = DALR or (DALR =ELR) Absoluteinstabilitywhen ELR > DALR or (DALR < ELR) Conditioninstabilitywhen ELR is betweenDALR and SALR.  Diagramsrepresentingatmosphericstabilityand instability.
In diagramabove. The line for DALR is below the line for ELR. Indicating thattheDALR is greater thantheELR and thereforethe air is cooling faster thanthe ELR leading at atmospheric stability. Inthis casethere is no verticalair – mass movement since the cold dense air mass tends to sink down to the surface.
In the diagram above: the line for SALRis below theline for ELR indicatingthat theSALRis greater thantheELR and thereforethe saturated air iscooling faster than the ELR Leading to atmospheric stability. Alsoin this casethe verticalair- mass movement is limited, sincethe denser air masstends to sink down to the surface. In the diagramabove, theELR is below the line for DALR indicating that the ELR is greater that theDALR and thereforethe dry pocket of air is cooling at a lower ratethanthe ELR, Leading atmospheric instability. Also in thiscase, the verticalair – mass movement is pronounced since the pocket air mass tends to risebecauseof buoyancyor lightness. Under this situation, thesecanbe condensation, freezing and precipitationinthe atmosphere. Stormsalsodevelop, affecting theearth's surfaceand its variousfeatures.
In the above diagram: One can find that beforecondensationis thelower altitude, theair is dry and DALR is greater thantheELR. The atmosphereexperiencesstability. As air is forced to risethe cooling processleads to condensationwhich saturatestheair. The saturated air becomeswarm due tothe additionof moisturewhich haslatent heat. It then startsrising spontaneouslywhile cooling at the SALR, which is lower thanthe ELR. This situationmanifests the attainmentofa stateconditionalinstability. CAUSES OF AIR – MASS ASCENT. Pocketsof air areforced to rise several ways, which include;
i) When the air- massis heated or warmed by conduction, air risesin conductiontheheat energy which is reflected from the earth’ssurface warmsthe air resting above; then verticalconvectionalcurrentssetsup. Thisphenomenon leads to the formationof convectionalrainand it is commonin the equatorialand tropicalareas. Theconvectionrainfalls in the afternoonand is usually accompaniedbyrainfalland thunder. ii) The pocket of air can riseafter being forced mechanicallytorise up the slope incasethe wind blows against themountainside. The air massthat rises cools leading to condensationand later the formationoforographic rain, which is commonin mountainareaslike Kilimanjaro, Uluguru, Rungwe, Meru and Usambara inTanzania.
iii) Thethird way involves the situationwhereone air – mass, usually warm is forced by another massof air which is usually cold. The warm air rises above thecold air creating a zone of contact inbetweenthem called front. In most cases of raising air a verticalelement is introduced which isa form of convergent rotation. Under thissituationa depressionis usually created, which isassociated with law pressure formationofclouds and rainfallformation. It should be noted that when the air-massiswarm, it tends to expand and it always lighter, such that it keeps on rising above. TYPES OF TEMPERATURE INVERSIONS a) According tothecauses, temperatureinversionscanbe categorized into four types namely : - Subsidenceinversions - Advectioninversions - Radiation(nocturnal) inversion - Frontal inversion
i)SubsidenceInversionis formed where the air is descending in the high pressurezones. The sinking of the air leads to compression, which in turn causestemporaryinversionat a higher level in the atmosphere. Thistypeof inversion is also called high inversion and usually last a long time. ii) Advectioninversion is caused by a warm air massadvancing acrossthe cold surface. The lower portiongets cold while the upper part remainwarm thiscan happenover thecolder sea in summer or over the land massin winter. iii)Radiation(nocturnal) inversionisthe type of inversionthat occurs during night when the land is very cold becauseof having lost most of the heat energy through radiation. Nocturnalinversionoccursexclusively over the land as the ground cancool much more quicklyafter sunset, thanthe sea. It is also called ground level inversion as it is near the surface. This type of inversion disappearswhenthe sun rises in the Morning. vi) Frontal inversion which occursasa result of the formationofwarm and cold front due to meeting of two air masses. Thewarm air rises over the cold air mass keeping the atmosphereabovewarm whilenear the surface. b) According tothelevel of occurrence:According tolevel of occurrence temperatureinversioncanbeclassified as ground level and high level inversions. i.Ground level inversion is the type of inversion that takesplace near the surfaceof the earth due to cooling, caused by the lose of radiant energy into thespace. The air near the surfacetends to be cooler thanthe air above it. Sinceit is in contact with thecold surface. It takes placeat night and disappearsinthe morning whenthe sun arisesNocturnalinversionis good.Example;
The above hypotheticaldiagramindicatesthattemperatureinversiontakes placenear the ground level due to the influenceof surfaceradiationsuch that as one moves from 0 to 45 meters abovethe sea level will experience the rise in temperature. After 45 metersof altitudethetemperaturestarts decreasing at a normal lapse rate. ii.High level temperatureinversion Takes placeat upper levels of the atmospherefor example, after 145 meters above the sea level . It canbe caused by air subsidencepresence of water vapour or a layer of Carbondioxideand Ozone. It is usually last longer than
the ground level temperatureinversion. iii.Theabovehypotheticaldiagram illustratesthat from 0 to 145 metersis above the sea level the temperaturedecreaseswith altitudeat a normal lapse and after 145 metersit tends to increasewith increasein altitude(temperatureinversionoccurs). ATMOSPHERE Thisis thethis layer of gasesheld on the earth by the gravitationattraction. Composition of atmosphere Describeand explainthe compositionof theatmosphereatmosphereis composed of the following;
i. Mixtureofvariousgases theseincluded oxygen21% nitrogen78% Argon 0.09% and Carbondioxide0.03%othersincludeneon, xenon, krypton helium and others in minutepercentages ii. Dust particledust particles maybe naturalor artificialwhere naturaldust particlesarethose caused by wind and volcanic eruptionwhile arterialdust particlesarethosederived from industrialpollution iii. Water vapour thisis colourless, odourless gas in form of water which makesup a perfect mixturewith gases. The degreeat which water vapour is present in the atmosphereintermed as humiditywater vapour condenses in term of rainsnow, mist excess water vapour bringsabout capitationinform of rainsnow, sleet and hail when water vapors is present in the atmosphereinsmall quantityextremedrynessof air many cause occur of hot desert. THE STRUCTURE OF ATMOSPHERE Atmosphereisdivided into layers according totemperaturetheselases are i. Homosphereand ii. Heterosphere A. HOMOSPHERE Thisis thelower part of atmosphererunning from 0-80km above the sea level. Thislayer has there sub layers which areTroposphereStratosphere and Mesosphere. 1. Troposphere Thisis thelowest part of homospherefound between 0-9milesor 0-15km above sea level, the layer is composed of gases water vapour and dust. All processes of rainformationtakeplacein this zone and temperature decreaseswith altitudeat a normal lapse rate. The lapse ratein Troprosphereis 0.6 ºC per 100 metreswhich is equivalent to 6.5ºCper 1000 metresrise. The lapse theresult of thefact that the earth'ssurfaceis warmed by incoming solar rotationwhich inturnheats theair next to it by conduction, convectionand radiation. Thetropopausewhich formsthe
upper limit to earth'sclimateand weather is marked byan isothermallayer where temperatureremainsconstantsat -80ºC. 2. Stratosphere Thisis thesecond part of homospherelying above tropopausebetween48 kilometresabove the sea level. Much of the zone layer is concentratewithin thiszone particularly15 to50 kilometresabove the earth’ssurface. Sometimestheterm ozonesphere is used to refer the layer where there is concentrationofozone gases. Temperatureremainsunchanged with increasing height at tropopausebut later it start to increasewith height the lower stratospherecover about 15 to25 kilometrefrom the earth'ssurface thisis the layer in which temperatureremainconstant. Thissteadyiscase in temperature(temperatureinversion) iscaused by concentrationzone (O3) thisgas absorbsincoming ultra violet (UV) radiationsfrom sun. The stratopausewhich markstheupper limit of thiszone is other isothermal layer where temperature doesnot changewith increasing height. 3. Mesosphere Thisis thethird part of homosphere lying abovestratopausebetween48to 80 kilometersabove the sea level where temperaturedecreaseswith altitudeup to -100ºCat 80 kilometersabove the sea level. Temperature falls rapidlyif thereis no water vapour, clouds, dust particlesor ozone to absorb incoming radiations. Thusthislayer experiencestheatmosphere lowest temperatureand strongest wind. Themesopauselike the tropopause and stratopausewhich istheupper limit of this zone records theminimum temperaturethatmayfall to -100ºC and thus shows no further changesin temperature. B. HETEROSPHERE Thisis is thesecond zone of atmospherewheretemperatureincreaseswith altitudefrom -100ºC at 80 kilometresto about 500ºCat 8o-5,000 kilometresabove the sea level. The increaseof temperatureisassumed to be so becauseof lack of water vapour and dust particleszone. The upper part of this zone is called Ionosphere which is sometimesdivided into exosphereand thermosphere. In the thermospheretemperaturerises rapidlywith height perhapsto reach 1500 ºC . This is due to an increasing proportionof atomic oxygenin theatmospherewhich like ozone layer absorbsincoming Ultra Violet radiations.
TEMPERATURE INVERSION Temperatureinversionrefersto the increaseintemperaturewith height above the earth’ssurface. Thisphenomenon is a reverse of the normallapse ratein the atmosphere; it isthe exceptionallapserate. This situationof increasein temperaturewith altitudeiswhat called reverse lapse rateor abnormallapse. In temperatureinversionit meansthat, temperatureinthe air far abovethe ground. CAUSES OF TEMPERATURE INVERSION I. Presence of ozone layer in the atmosphere Ozone in the atmosphereabsorbsenergyfrom the sun especially ultra violet(UV) rays. The reactionbetweentheserays and ozone gives out heat whit warmsthe atmospherefrom the ground surface. II. Formation of fronts Thistakes placewhen twoair masses of different temperaturemeets. On meeting thewarm air rises above the cold air. Under thissituationtwo fronts areformed such that thewarm front is aboveand the cold air leading to temperatureinversion. III. Air subsidence When thereis high pressure air tends to descend or sink down. The downward of air leads to compressionor frictionbetweenmolecules thus creating warm conditioninthelevel. IV. Atmosphere components Water vapour and dust particlesat a higher level, keep the atmosphere warmer thannear the surfacesince it preserves energy from the sun for a longtimewhich leads to temperatureinversion. V. Advection When the massof warm air passesover the cold surfaceitslower part is cooled by the cold surfaceleaving the upper portionwarm becauseof being far awayfrom the influenceof thiscold surface. VI. Radiation
Radiationofinfra red energy from the earth'ssurfacemakesthe ground cool very quickly. The cold surfacecools the air immediatelyaboveleaving the other layer far above warm. For example; during clear settled weather, as radiationofheat takes placeduring thenight the air on hill - slopes is rapidlycooled and thusdense air drawndown wardsfilling valleys or basinswith cold air possibly at temperaturebellow freezing point, when the upper slope are markedlywarmer. VII. Water vapour Water vapour at higher altitudeskeepsthe atmospherewarmer thanair the surfacesince it preserves heat energy for a long time. Thisalso causes temperatureinversion. EFFECTSOF TEMPERATURE INVERSION 1. The warmer layer of air above the cold air may lead to increasein atmospherestabilityand verticalair mixing assuch the temperatureis always calm with no precipitation. But when inversionoccursdue to the development of precipitationand formationof cyclonic storm. 2. Temperatureinversionleadsto the formationof fog and smog. Smog is commonin the industrialized areaswith a of smoke which is produced from industries. Thesmoke so produced mixeswith fog to from smog. 3. Air pollutiontakes placewhen there is temperatureinversion.Theair is polluted becauseof the sinking of particleswhich arehanging inthe atmospheredue to the fact that the warm air abovethe cold air is less dense and thus not capableof holding the particlessincethey aredenser thanthe warm air. The sinking down of air to the lower atmospherelevel causesair pollution which affect humanhealth, animaland plants. It can causeitching of body, inflammationofeyes and coughing. THE HEAT BUDGET The sun's energy is called insolationor solar radiationwhich turnsintoheat energy at the earth surface. Insolation travels through spacefrom the sun inform of waves and interact with outer edgeof atmospherebeforereaching the earth'ssurface. Totalamount of solar radiationreleased from the sun is 100% sincethe earth is neither warming up nor cooling down, therebe a balancebetweenincoming insolationand outgoing terrestrialradiation. The atmospheric conditionthereforereducestheamount of solar insolation
through threeprocesses; 1. By absorption: About 15% of totalsolar radiationisabsorbed inthe atmospherebythe atmospherecomponents. Thegreater absorbersare water vapour, dust particlesand clouds. 2. By reflection: Certainamount of solar radiation isreflected backinto the spaceby clouds, dust particlesand ground. The amount of insolation reflected depends on the surfacebut the averagereflectionamountsto40% of totalinsolation. ALBEDO Albedo refers to the percentageexpressionofthe ratiobetweencoming radiationsand theamount reflected. Clouds and to a less extent, the earth surfaceare theprincipalreflectorsof the incoming radiationsbackinto space. The albedo varieswith cloud type from 30-40% inthinclouds, to 50- 70% in thicker stratus and 90% incumulonimbuswhereonly 10%
insolationreachesthe atmospherebelow the cloud level. Albedo also varies over different land surfacefrom less than 10% over oceans and darksoil, for 15% over coniferousforest and urbanareas25% over grassland and deciduousforests40% over light coloured desertsto 85% over reflecting fresh snow. Thisreducespossibilityat icemeet and disappearson mountaintopslike Kilimanjaro. THE OZONE LAYER The ozone layer is found withinthe stratosphereand it sometimesre- termed as a shield of life. The layer is highly concerned with humanand all other earth life and it sets in at an altitudeof about 15km and even upward to about 55 kilometers. Thislayer serves as a shield protecting the troposphereand the earth surfacefrom most violent raysor radiationfrom the sun. If these rays were to reach the earth directly, all bacteriaexposed would be destroyed and animaltissueswould be damaged.Destructionof thislayer by some scientific discoverieshasmadetheintensityof ultra violet rays reaching theearth surfaceto increasecausing globalwarming. If thissituationisleft to continue, it will causesuffering particularlycancer , crop reductionin yield and killing of organismson land, water and air. FUNCTION OF ATMOSPHERE 1. It is an insulator: It moderatestemperatureduring night winter. 2. It is a filter: It filters solar insolationthrough ozone layer and provides a layer through which meteorsare burnt intogases. 3. It is a scientific field whereradio, radar, televisionand other communicationincluding air transport and telephonesare done. 4. It has hydrologicalfunctionwhere rainfallis formed. 5. It support itslife through breathinginanimalsand respirationin plants. CLIMATOLOGY Climatologyisthe studyof climatethat dealswith spatialdistribution atmospheric phenomena. It mainlydeals with definitionand descriptionof different climatesintheir geographicalsettings.
Meteorology isthestudy of weather. It is a scientific studyofthe physical process constantlyat work in the atmosphere. It is highly applied in the forecasting ofthe futuretrend of the weather. It is a branch of Science which deals with the conditionsof or withinthe atmospheresurrounding the earth. Climatologyand meteorology arethe studiesor thesciences which are concerned with the study of atmosphereand its elements like weather and climate. CLASSIFICATION OF CLIMATES By studying theweather, the atmospheric conditionsprevailingat a given timein a specific placeor area; it is possible to makegeneralizationabout the climateof that placeor area basing on the averagenormalcondition over a period of timeusually 35 years. In seeking a sense of order; the Geographerstryto group together those partsof world that have similar measurableclimatic characteristicsintemperature, rainfalldistribution winds, etc. Classificationofclimateisdone in different systems.  Greek’s classificationsystem.  Germanyclimatologist classificationsystem.  Koepen's temperaturezones classificationsystem.  Miller'sclassificationsystem. GREEK CLASSIFICATION SYSTEM The early Greeks divided the world intothree zones based upon a simple temperaturedescription. A classificationofclimatebyGreek is based on temperaturecontrolofthe climateand they completely ignored precipitation. Under thisapproach climateisdivided into: i) Tropicalclimatewheretheamount of temperatureishigh. ii) Temperateclimatewherethetemperatureismoderatei.ebetweenthe tropicaland polar temperaturecondition. iii) Polar climatewherethe temperatureisextremelyLow. KOPPEN’SCLASSIFICATION SYSTEM
In 1918 Koppen advanced themodern classificationofclimate. To support his claim that naturalvegetationboundariesweredetermined byclimate, he selected as his basiswhat he considered were appropriatetemperature and seasonal precipitationvalues. The classificationofclimateby thisapproach isbased on the duration above or below the value belt. By thisapproach climateisclassified intothe following belts;  Tropicalbelt The climatehaving 12 months with temperatureabove20oC.  Sub- tropicalbelt The climatehaving 4-11months with temperatureabove20oC.  Temperaturebelt The climatehaving 4 – 12 monthswith temperatureranging from 10oC– 20 oC.  Cold belt Thisinvolves those areashaving 12 monthswith the temperature ranging from 10ºCto 20ºC.  Polar belt The climatehaving 12 months with temperaturebelow 10oC. CLASSIFICATION BY GERMANY CLIMATOLOGIST According toGermanyclimatologist, climatedivided intothefollowing types;  Hot zone climate The climatewith temperatureisothermof20oC annually.  Cold zone climate The climatewith annualtemperatureisotherm of10ºCor below.  Temperaturezone The climatewith temperatureisotherminbetween10oC – 20oC.
MILLER’S CLASSIFICATION SYSTEM In Britain, inthe 1930s, Miller proposed a relatively simpleclassification based upon five latitudinaltemperaturezones which he determined by using just threetemperaturefigures. Thisisthe most popular method of climateclassificationtodaybecauseit combinesboth mapsof temperatures, showing temperaturebymeansof isothermsand map of rainfallshowing rainfallby meansof isohyets. It shows a close relationship to vegetationzones and thisit is easier to use and convenience. - The structureofclimateclassificationisasfollows;  Hot zone - With temperatureabove20oC.  Warm zone - With temperatureranging from 10oC – 20oC.  Cool zone - With temperatureof 10oC.  Cold zone -With temperaturenear to0oC .  Arctic zone -With temperaturenear to0oC and below. CLIMATIC FEATURES  Dry warm summerswith offshore trade winds.  A concentrated rainfallin winter with offshore westerly.  Bright sunny weather with hot dry summer and wet mild winter.  Presenceof local winds around the MediterraneanSea e.g. moroccoand Muscat.  Annual rangeof temperatureishigh about 11ºC  Rainfall is moderateabout 838 mm and normally falls during winter and it is cyclonic raintype.  Summer temperatureisabout 21ºCand winter is 10oC, hence high rangeof temperature. VEGETATION Evergreen coniferousforest, Mediterraneanbushesand grassessemi arid shrubsas well as grasses, evergreenMediterraneanforests. ECONOMIC ACTIVITIES: Crop cultivationdue to high rainfall and moderatetemperature, Animal rearing i.e. transhumance(pastoralism) orchard farming with different kind of fruitsand vegetable(market gardening).
EQUATORIAL CLIMATE Thistype of climateoccursasa belt around the world at about 5º North and South of the Equator but it is also found around 5º-10º North and South in some places. The continuityofthis climatehowever is interrupted in several places by mountainssuch as Andes of South America and theEast Africa high lands. DISTRIBUTION OF EQUATORIAL CLIMATE Zaireand Congo basin, Amazonbasin, East Indies, South Ivory Coast, and WesternCoast Nigeria, EasternCoast, Malaysia and North eastern Australia. PROBLEMS OF CLIMATE CLASSIFICATION Classificationofclimateposes moredifficultiessincethereis no clear boundarydue to the fact that climatesareTransitional. Thusall classificationshaveweaknesses, non is perfect because; - They do not show transitionzonesbetween climates, and after the divisionlines arepurely arbitrary. - They do not allow for mesoscale variationsuch asthe lake and district or microscalevariation(localvariation). - They can be criticized for being either too simplistic (miller) or too complex. - They ignorehumaninfluence and climaticchangeboth inthe long term and the short term. - Most tend to be based upon temperatureand precipitationfigures, and neglect recent studiesin heat and water budget, air massmovement and the transfer of energy. - All suffer from thefact that some areasstill lack the necessary climatic datatoenablethem to be categorized accurately. GENERAL CLASSIFICATION OF CLIMATE A: MEDITERRANEAN CLIMATE The warm temperatureWesternmarginor the Mediterraneanclimateis
confined in the Westernmarginof continentallandmassesbetweenlatitude 30o-40o North and South of theequator. Areas involved CentralChile, California, CapeTown, SouthernAustria, South West Australia, SanFrancisco, and partsof Morocco. CLIMATE CHANGE It has been noted that a certainarea experiencea certain climaticcondition. Thereforeany deviationfrom the expected conditiondenotesfor a climatic change. There areseveral evidences of climaticchange. Theseinclude; rocks arefound todayin areaswhich seems to have a different climatic conditionunder which they formed, fossil landscape, sea level changes, shifting of vegetationbeltsSahara, etc. CAUSESOF CLIMATE CHANGE For the factorsor causesof historicalclimaticchange, refer to the theories which explainthe iceages. Note: However todaythe world is experiencing theso called “Global warming” Scientistshavereached a consensus on this point of global warming asa published by the InternationalPanelon climatechange (IPCC). Global warming mayrefer to the world wideincreasein the lower atmospheric and terrestrialtemperature. Thismaybe as a result of increase in the concentrationof one or moregreenhouse gases(GHG) as well as the Ozone layer depletion. Global warming ismainlytheory assertsthat the increasing levels of GHG will progressively trap moreof the Earth'sheat, graduallywarming theglobalclimateasmuch as 3 to 9 degrees. However the reasons which have been put forward to explainthe scenarioarerelated to those activitieswhich pump theGHG intothe atmosphere. Therefore manthrough different activitiescarried out for his triggersoff climate change. The Marjoryinclude; CFC’s and Halons: Scientistsfirst suggested in1974 that theworldwide use of CFC’s and halons could be destroying theOzone layer.
In 1982, British scientist for thefirst timedocumented theexistenceof a largehole in the ozone layer over the Antarcticathat had beentheoretically predicted earlier. In thiscase theemitted CFC’s and halon react with the ozone in the stratospheretobe depleted which formally absorbed some incoming radiation. CFC’sis emitted from coolants in air conditionersand refrigerators, propellantsinaerosol spraycans, cleanersfor electronic parts such as computer chips, productionand burning ofplastic foam products. Fossil fuel burning: Like coal burning inindustriesbeforethe introductionofalternativeenergysource; this could emit large amountsof GHG such as carbondioxideand methaneintothe atmosphere. The industrialrevolutionsparked off the extractionof the coalto run the machinesor industrieswhich had sprung up. The perpetualburning meant continuousemissionof carbondioxideand sulphur hence contributing through the greenhouseeffect. Deforestation: Thisinvolve the clearing of vegetationand burning of grassland for either establishment ofsettlement/industriesor agricultural activities. Thisresultsinto the accumulationofcarbondioxidewhich would have been taken up by plants. Cultivation of rice: Thisis couple with the release of methanegasinto the atmosphere. Livestock farming: Animalslike cattleproducemethanegasdue to their microbialfermentativereaction. Thereforethedumping ofcow dung will release too much methaneas it decomposes. Animalhusbandryisthought to be responsiblefor much of the increase. Ozone layerdepletion: The chemicalreactionswhich takeplace betweenthe GHG may breakdown or deplete the ozone layer. Thismakes it thinner or drill a hole making it easier for more insolationto pass through to reach surface. Thereforethe more insolutionreaching theEarth’s surface, the more thetemperaturewillincreasehence climatechange. Industrialization: Someindustriesemit GHG intothe atmosphereto changethe climatethrough thegreenhouseeffect aswell as reacting with the ozone layer. Transportation: Automobileemit carbondioxideduring thecombustion of fuel in the engine which act as GHG to contributetheglobalwarming.
EFFECTSOF CLIMATIC CHANGE The effects we feel or observe are rarely, if ever, the effects of a single factor, they are combined impactsofthe whole of factors(pollutants) acting over the totallife span, and frequentlythe effects are synergistic. For instance both plant and animalsmay be so stressed by climatic changeand become vulnerable to other environmentalfactorssuch as attackbyparasitesand diseases. Given the complexityofthis situation, it isextremelydifficult todetermine the effect of any particular factor. Neverthelesssome significantprogress has been madeto link climatechangeand some effects, these mayinclude; Soils: Higher temperaturescould reducethe water holding capacitiesand increasesoil moisturedeficits. It should be noted that climatechangewill alter the chemical, biologicaland physicalpropertiesofthe soils. The expected temperatureraiseand related prolonged droughtswill increase the rateof soil organic matter decompositionthusaccelerating land and soil degradation. Thiswillescalatesoil fertilitydepletionresult into low productivity. On theother hand, theanticipated floodsin highland areas will acceleraterunoff and soil erosion. Flora and fauna: Higher temperaturesand increased water deficits could meanloss of several species. Thisis becausethe exiting flora and fauna cannot adjust drasticallyto acclimatizetothenew climatic conditions. For instancethe increasing temperaturemayaffect theaquatic animalslike fish which are used to cool/cold environment. In which additiontothat, the changein climatewillchangein the qualityof the different habitatsand consequentlyall the flora and fauna in them. The habitatsmayinclude; wetlands, forests, etc. Agriculture: Agriculturalactivitieswhich entirelydepend on rainfallwill be hit by climatechangesuch as prolonged drought, unreliablerainfallare evident in some areas. Droughtslower the productivecapacityof rain –fed agriculturehencereducing theagroexports, increasing food prices, nutritionaldeficienciesand destabilizethemacroeconomies. Cerealswill be hit by dry seasons hence a reductioninthe productionofcrops. For instanceaccordingtoNAPA (2007), intheLake Victoria basininTanzania, maize productivityisestimatedtoreduceby 17% due to the anticipated
climatevariabilitymanifestinginform of temperatureraiseand reduction in rainfall. The increasein thenumber of pest and diseases due to climatechangeisa set-backinthe agriculturalactivities. Coastal regions: Rise in sea level, increaseinheight of stormsresult into more flooding especially around estuaries. Flooding affectshousing, industry, farming, transportand wildlife. Flooding increasesthe susceptibilityof water borne diseasesalong lake shores, coastlines, and other placesliable to flooding. For instanceinUganda the outbreaksof malaria, bilharzia, and other water bornediseases were reported to as often occurring during and immediatelyafter floods, (UgandanNAPA 2007), According totheTanzania NAPA (2007), Malariaprevalencehasbeen reported tom occur in areaswhere it wasnot commonly found in the previousdecadefor examplein some partsof Kagera, Musoma, Mwanza in Tanzania; Kisumu and Kiisi in Kenya. In additiontotheeven the icecaps for instanceon the KilimanjaroMountainhastremendouslyreduced as a result of accelerated icemelt. It is also anticipatedtoacceleratethepopular icecap melt too. During the century, sea level rose about 15 cm (6 inches) due to melting of ice and expansionof warmer waters. Models predict that sea level may riseas much as 59 cm (23 inches) during the Century, threatening coastalcommunities, wetlands, and coralfees. Arctic sea iceis melting. The summer thicknessof sea iceis about halfof what it was is 1950. Glacier and permafrost are melting for instanceover the past 100 years, mountainglacier inall areasof the world have decreased in size and so has the amount of permafrost inthe Arctic. Water: Water ismost likely to becomescarcedue to the increased ratesof evaporationaswell as the variationintherainfall patterninsome areas. The anticipated climatevariabilityinform of long droughtswill worsen the availabilityofand accessibilitytocleanwater particularlythepoor or those who depend on rivers, streams, boreholes. Thisis becausesuch sourcemay be dried out or lowering of water levels, in springs, rivers, underground aquifers. Communitieswillveer to any availablewater irrespectiveofits qualityhence pausing a danger for water borne diseases, hardenthe productionof hydroelectric power, limit water transport. For instancethe declining water levels of lake Victoriain2002 to2004 left many boat landing sites and harbourshigh and dry thusaffecting water transport
negatively; the extensionof the Owen falls dam (Kiira and Nalubaale) opened in 2000 appearstohave been designed to operatewith conditions of high averagewater levels seen between1960 1990 basing on the inability of thepower plant to operateat full capacityduring thelow water levels of 2002. In Tanzania, thepower cut off wasextremealso as the mega like Kidatu could not operateat full capacity. Thiswasportrayed through a more than12 hours cut off. Tourism: It predominatelydependson thebeautifulglamorousnatural featureslike mountains, habitatsand associated flora and fauna. Climate changewill distort the naturalenvironment toas well affect the tourism sector negatively. To makemattersworse, floods may destroythe roads to accessthe distant tourist sites. Thisis becausemost of the tourists attractionsitesarelocated in theremote areasof which their roads are impassableduring therainyseason. Sincethe rainfallpatternisunreliable and unpredictable, thiswillimpedethe movement of the touriststosuch sites. The scenariowill ultimatelyslump the economieswhich depend on tourism. Climatechangewill affect all thedifferent sectors of a countryand ultimatelythemicroeconomicalstatusof thegreatlyaffected areasor countriesmoreso the developing countries. Thisis becausethey may not be robust enough to copeup with the changeshence rendering them variabilityand change. Strategies to address Climate change. It is responsibilityfor all people at a household or communitylevel, NGO’s, government, regionalgroupings, and the internationalcommunityat large to striveto reverse the situation. Thisisbecauseeveryone contributestothe existenceof the problem though the magnitudeof contributiondiffers. To makemattersworse, theeffects cut across i.e affectsall. However it may be difficult toreverse thesituationbut theefforts should revolve around strategiestoadapt tothe climatechangesaswell as reducing theemission of GHG. Some of the avenues to fight climatechangemayinclude, Renewable energy sources: Countriesshould adopt the use of renewableenergy resourcessuch as solar, nuclear, biogas, geothermal, etc which are environmentallybenign.
In thiscase they should advocateagainst theuseof fossil fuel such as coal, petroleum and naturalgaswhich emit theGHG. Afforestation: people should indulgein the policieswhich encouragethe plantationoftrees such as agro-forestry. Thisis becausetheyact as carbon sink to minimizetheamount of the carbondioxideinthe atmosphere. Ambient standards: The Internationalcommunityshould agreeon the maximumamount ofGHG to be emitted bya source point like an industry. In the extremecaseswhere theGHG can’t be curtailed, thestrategymaybe inevitable. Use of ethanol or gasohol: The vehicles and other automobilesmayreplace petroleum with the use of ethanol and gasohol Biomassfrom sugar cane canbe used for the productionofethanol which replacethe usageof fossil fuel (petroleum inclusive) thiswill minimizetheGHG which could be emitted thecombustion. Abatement policies: Countriesshould be stringent onthose who emit more thanthe ambient standards. Abatement policiesmyinvolve thepay or cost to cater for the damagecaused bythe extra emissionsthecost as disincentivestopollution. Comply to the relevant Conventions: signatoriesshould implement accordingly. For instancethe 1985 Vienna Convention on the protectionof the ozone layer Depletion. The convention requirespartiestotakeconcern to the assessment of the cause, effects of ozone layer depletion as well as transmissionofinformationand exchangeof informationand Technology to reduceozone layer depletion. Note; the convention wasamended in Montreal1987 to becomethe protocolon substancethat depletetheozone layer. It was later revised in 1990 in London and Stockholm in1991. It representsa much more significant agreement thantheconvention. It sets a firm target for reducing and eventually eliminationofconsumption and productionofa rangeof ozone depleting substances. It recognizesthe equityof treatment of all Nationsthat produceozone depleting substance including thedeveloping countrieswhich produceless.
The protocolalso deals with the problem of non- partiesby banning trade in ozone depleting with those statesto controlthe use.  Produceless ozone depleting substances. Thisisattained through technologicaltransfer.  Restrict theimportationofozone depletion substancesthrough identifying and monitoring mechanism. For instanceRevenue authoritieslikeTRA, URA jointlywork with the Environment authoritieslikeNEMA, NEMCin Uganda and Tanzania respectively. In thiscase, the environmentalauthoritiesspecifytheozone depleting substanceswhilethe revenue authoritiesescalatethetaxestonarrow down the importation.  Research and educationofthe stake-holdersabout the substances. Thiswill also increaseon thenumber of technicalofficerstoease the monitoring.  Internationalcooperationthrough thesharing and transfer of information.  Establishment ofincentiveslike subsidyto encouragetheuse of substitutesand disincentivestoprohibit theof ozone depleting substancethrough taxation. There arevery manykey players toward theadaptationtothe climate changeand chopping ofGHG emissions.

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SPACE DYNAMIC

  • 1.
    SPACE DYNAMIC WEATHER ANDCLIMATE (a) Differencebetween weather and climate There is a slight differencebetweenweather and climate. Weatherrefersto as the actualstateof atmosphereand climaterefersto the averagestateof atmosphere. By definition: Weather is the conditionof the atmospherewith regard toitselements for a certainplaceand at specific moment. It is the dailyatmospheric condition of a placeat particular time. It isthe conditionof being hot, windy, cold, foggy, or cloudy. Weather changesfrom timeto timeand from place to place. The conditionof the atmosphereisdetermined by the elementsof weather which are: o Temperature o Humidity o Atmospheric pressure o Clouds o Precipitationand o Winds Climate isthe averageatmosphericconditionover a long period of time over 30 to 40 years withina specific geographicalarea. Factors that influence weather and climate Weather and climateareinfluenced by the factorslike; -Temperature -Precipitation -Humidity -Pressure
  • 2.
    -Winds -Cloud cover -Sunshine -Altitudeand -Oceancurrents. Measuring andrecording theelementsof weather and climateis done at a weather station. WEATHER STATION isa placethat is set asidefor the purpose of observing measuring and recording weather elements. Element of weather 1. TEMPERATURE Temperatureisthedegree of a heat of a body. It is a measureor degree of hotness of an object or place .Temperatureismeasured by an instrument called thermometer. Thelines joining all places with equaltemperatureare
  • 3.
    called isothems RECORDING TEMPERATURE 1.The mean(or overage) dailytemperatureisobtained byadding thedaily maximumand the daily minimum temperatureand dividing thesum by two. 2. The daily rangeof temperatureisobtained bysubstracting thedaily maximumtemperaturebythe daily minimum temperaturewhich is, daily max temp – daily minimum temperature
  • 4.
    3. The mean(or average) monthly temperatureisobtained bydividing the sum of daily meantemperatureofa month by thenumber of days in that particularmonth 4. The monthlyrange of temperatureisobtained bysubtractingthelowest daily temperatureofa month from the highest meandaily temperatureof that particular month. 5. The mean(or average) annualtemperatureisobtained bydividing the sum of the monthly mean temperaturesofthe particular year by12. 6. The meanannual rangeof temperatureisobtained bysubstracting the lowest mean monthly temperatureofa year from the highest meanmonthy temperatureofthat sameyear. FACTORS AFFECTING INSOLATION ORTEMPERATUREOF A PLACE Factorsthat influencethe amount of insolationreceived any point and thereforeits radiationbalanceand heat budget varyconsiderablyover time and space.Theyincludethe following. (a) Seasons and angle of incidence The earth as a planet moves along its orbit throughout theyear under this movement inclinationof the earth variesand theangle of which the sun rays strikesthe earth'ssurfacechangeswith seasons. Also thedistanceof the earth from the sun variesfrom month to month.At spring and autumnequinoxes.(21th March and 23rd September) theangleof incidenceat theequator is 90º making anarea to have high temperature throughout theyear.Temperatureisdistributed equallyinboth hemispheres.At thesummer and winter solsctice(21th Juneand 22nd December) due to earth tilting thesun is overhead at the tropicswherethe hemisphereexperiencesummer willreceive maximuminsolation.Theangle of incidenceisthe most important factor which influencestheamount of insolationof a place on theearth'ssurface.
  • 5.
    (b)Distance from thesea There is often a considerabledifferencesbetweentemperatureofland and water surface. The reason for thisis that land surfaceheatsand cool more slowly than thesea. Due to this summer temperatureincoastalareasarelower than in continentalinterior. Likewisewinter temperaturewillbe higher in coastal areasthanin continentalinterior ifthe windsblow towardstheshore During the day and during night the situationisrelated toland and sea breeze. Areaswhose temperaturesaregreatlyaffected bythe sea are reffered to as maritime.Thegreater distancefrom thesea the colder the winter it will be and the warmer the summer develops.
  • 6.
    (c)Altitude The rateat whichtemperaturedecreaseswith increasing altitudeiscalled lapse rate. Normallyair temperaturedecreaseswith increasing heightat a rateof 0.6ºc R.r 100 meters.Thisisbecausewhen earth surfaceis heated it passes itsheat on air making atmospherebeing heated from below and not directlyfrom thesun.This affect temperaturebecausethehigher you go the cooler it becomes. Altitudeexplainswhyhighlandsin the tropicsareever
  • 7.
    cold e.g Mt.KilimanjaroinTanzania. (d) Aspect Thisrefers to the directioninwhich a slope falls.Some slopes are exposed to the sun thanothers.The atmosphereofthe north facing slopes of highlands in the northernhemispherealso called ubac arecooler than theslopes facing south adret.Thesamething appears inthe southernhemisphere (e) Latitude It is the angular distancefrom the equator tothe poles. It determinesboth the length of day throughout theyear and the intensityand possible durationof sunlight received.
  • 8.
    As one movespole wardsfrom theequator he experiences gradual progressivedecreaseintemperature. Thisisbecausethe sun strikesthe equator moreintensitythanit does in the poles two observations canexplainthis phenomenon. (i)At the equator thebeam of light strikethe earth'ssurfacecovering a smaller surfacearea thanin the poles wherethe same beam of light covers a larger surfacearea. (ii)At theequator thebeam of light striketravels a short distancehence experiencing lessatmospheric effectslike absorptionreflectionand scattering.At thepoles thebeam of light travels a longer distanceand it experiencesmoreeffects in the atmosphere. (f) Cloud cover The atmosphereof areascovered with heavy clouds is cooler thanthat of areaswith clear skies.Thisis because cloudsprevent insolationto reach sand sea surface. (g) Length of day and night Insolation is only received during day light hours and reachesits peakat noon .The longer the period of solar insolationthe greater thequantityof radiationreceived at a givenplace on theearth'ssurface.Thereareno
  • 9.
    seasonal variationsat theequatorwheredays and nightsareof equal length throughout theyear.In contrast polar regionsreceiveno insolation during part of winter when there is continuousdarknessbut may received up to 24 hours of insolationduring partsof the summer when the sun never sinks below the horizon .This occursin thelands of the midnight sun (f) Prevailing winds. Temperatureofthe wind is affected by the temperatureofit'sarea of origin and of the surfaceover which it blows normal windsblowing from the sea during winter warmstheatmosphereof the land near thesea while winds blowing from the sea during summer cools the atmosphereof thecoast (g)Ocean currents Warm oceancurrentscarrywarm water polewards and rise the air temperatureofthe maritimeenvironmentswheretheyfollow while cold ocean currentscarrycold water to the equator and so lower the temperatureofthe coast areas. Factors affecting the flow of ocean Currents Oceancurrents – this is the horizontalmovement of masswater in a defined direction.Themovement is due to densityvariationat various depthsgovernent by the temperatureand salinity.The meeting of two currentsconverging uponone another causessinking of water which counter balanceswith ascending masses.  Salinitydifferences Density of ocean water is caused by amount of salts the more salt in an ocean thedenser the water will be.Denser water sinks in water with low densitywhich causes the formationofocean currents.  Temperature Temperaturecausesdifferencesinwater densitywhich causesocean water to move. The cold water is denser than warm water, thistendsto make polar cold water sink to the bottom thenflow downwardstowardsthe equator whilethe warmer less denser water at the tropic moveson the
  • 10.
    surfacetowardsthepoles .After beingcooled it sinks againand moves towardstheequator hence the oceancurrent.  Prevailing winds When wind blows over oceansurfaceit pushes water surfaceand forms the ocean current .Prevailing windsthereforecausethewater to move to the directiontheyblowing to winds causedrift currents. Anexampleof drift currentsis the north Atlantic drift which iscaused by the westerly windsin the Atlantic ocean.  Rotationof the earth Thiscauses the current flow to be affected as they aredeflected or pushed according toFerrell’s law. Ferrell’s law slatesthat"Anythingmoving freely in the northernhemispherewill be deflected to itsright while in the southernhemisphereit will be indirectlythough thewinds where in the northernhemisphereoceancurrent are deflected to their right whilein the southernhemisphereto their left ".  Shapeof landmasses The flow of ocean water canalso be directed bythe landmass.Theocean currentsareturned from their straight coursebythe shape of adjacent landmassor coast line. What isa temperatureanomaly? The term temperatureanomalyis used specificallytodescribetemperature differencesfrom a mean.It shows the differencebetweenthe mean temperatureofa placeand the meantemperatureofother places with the samelatitudein thesame month. For example:Anarea which has a mean Januarytemperatureof4ºc, which is 20ºc higher thantheaveragefor other locationlaying at 58 degree latitudenorth.such anomaliesresult primaryfrom theueven heating and cooling rates of land and sea and areintensified by the horizontaltransfer of energy by oceancurrentsand prevailing winds. 2. ATMOSPHERIC PRESSURE Air has weight and therefore it exertsthe pressurecalled atmospheric pressureon the earth surface.Pressurevarieswith thetemperatureand
  • 11.
    altitude, and aninstrument which measurepressureiscalled barometer. There aretwo types of mercury (i)barometer (ii)aneroid barometer The lines which join all placeswith equal pressureare called bars.Thus pressurevaries from one place to another it is not the same in one or all the regions. FACTOR INFLUENCINGVARIATION IN ATMOSPHERIC PRESSURE  Temperature As temperaturedecreasepressurerisesat the sameheight due to low temperaturecold air tend to sink, thus inducing high pressuretodevelop But as temperatureincreaseshot air tendsto rise making it possible for low pressureto develop over thearea.  Altitude Usually pressureof the atmospheredecreasewith increasing height. Pressureis therefore lower at the mountaintop thanat thesea level.This is becauseat the sea level air hasto support a greater height thanit does on the top of mountain.Thusthereisless force or weight of air at the mountain top thanat the sea level.
  • 12.
     Revoluationof theEarth The earth revolutioncausesseasons wheresome seasons arewarm while others arecold .Revolution of the earth affectsthe positionof the low pressurebelt i.e doldrum. Normally doldrum moves northwardsand southwardsof the equator depending onthe seasons. Earth rotation asa ball causesformationof subtropicalhigh-pressurebelt around 35º north and south of the equator whereair sinks down and gets compressed .Due to thiscompressionthe sinking of air is heated up and rises again. Thesame situationtakesplacearound circumpolar or temperaturebelt around 60º north and south of the equator.Thesearethe areaswhere the warm subtropicalair risesover the cold polar air expands and getscooler.Thissituationresult intoDepression cyclonic or frontal. PLANETARY PRESSURE BELTS THE WORLD PRESSURE BELTS These canbe analyzed according totemperatures: (i)Equatoriallow pressure belt / equatorinallytrough Thisis called doldrum it is located around 5º north and south of the equator.Theair hererises due to high temperatureit isa wind a convergencezone. This meanswinds meet there and it is called intertropicalconvergencezone (ITCZ) (ii)Subtropichigh pressurebelt (Horse latitudes) Thisis located at 30º north and south of the equator with descending air current due to heat of temperature. High pressureis attributedby accumulationofcold air which moves from the equator towards poles.This belt is also referred to as the"horse belt". (iii)Temperaturelow pressure belt (sub polar low temperaturebelts) Thisis found at 60º north and south of the equator. It is also known as cyclonic activities zoneor zone of convergence. Existanceoflow pressureis mainlydynamic rather thana result of temperaturechange.
  • 13.
    (iv) Polar high-pressurebelt Thisisconfined at 90º north and south of the equator. Pressureis permanentlyhigh due to low temperatureattributed bya dense descending air from the temperaturelow pressure belt. 3. SUNSHINE Thisis another element of weather. The durationofsunshine is partyof a functionof latitude. For the hours of light (that ispossible sunshine) vary with these season in different latitudes.It is also a functionof daytime cloudiness . MEASUREMENT ANDRECORDING OF SUNSHINE The durationof bright sunshineismeasured by means of campbellstokes recorder, a solid sphere of glass 10cm in diameter. Thisform the rays of sunshine onto a sensitized card graduatedinhours and so burn a line during thetimethe sun is shinning .Faint sun,light sun, near dawn or dusk or when the sun is partiallyabscured isnot recorded .Tables of sunshine
  • 14.
    data areprepared fromthese record, in the form of either absolutesolution in hours per day or as percentageofpossible sunshine per dayor month. When meansfigureshas been obtained over the requisitenumber ofyears, the value for each statecanbe plotted, and lines of equal meandurationof sunshine isohels can be interpolated. 4. HUMIDITY Thisis refered to as the atmospheric moister.Themoister is obtained from varioussources such as oceans, lakes,seas, dams,pondsand rivers. It is of high importanceasfar as weather as climateisconcerned. Air absorbs water through theprocess of evaparationwhich result in water changing from itsliquid stateto gaseousstate,thegaseousstateis called water vapour. The amount of water vapour in the air is called humidityand it is measured by an instrument called hydrometer placed inthe Stevenson screen.
  • 15.
    FACTOR INFLUENCINGHUMIDITY -Air pressure Whenair is compressed, it warmsup and its densitybecomeslower .Thus at low altitudewherepressureis high air will absorb more moister. At high altitudewherepressureis lower air expandsand cools and itscapacityto absorb moister isreduced. -Latitude Humidityhigher inlower latitudesthaninhigher latitudebecausethere is greater rateof evaporationat lower latitudesdue to high temperature.Likewisethemount of moister in the air is higher in summer . -Temperature Arisein temperaturelowersrelativehumidityifthe amount of moister remainsconstant becausewhenair is heated it expands.Thevolume
  • 16.
    increaseand therefore distributionofwatervapour per unit.Volume becameless.The air will have a greater capacityof holding more water vapour if air is cooled it contractsand decreaseinvolume making thespace which moister canoccupybecomeless .That is why if air continuesto cool it will reach saturationand it getsrid of excess water vapour through condensation. -Moisturesupply If the supply of moistureincreasestheair will have moreof it ,they making absolutehumiditytobehigher .If the temperatureiftheair increasesit will absorb even more moisture.Thissituationmakesallplaces which are near large water bodiesto be humid especiallyif the temperature is high causing a lot of evaporation. Areasthat arefar awayfrom large water bodiessuch as desertscenter has little water vapour the air has high capacityof holding moisture. IMPORTANCE OF WATER VAPOUR IN THE ATMOSPHERE - Evaporationformsprecipitation,which providesfresh water plantsand animals. - It absorbsboth incoming and radiated energyfrom the sun. - It conveys Latent heat into the atmosphere The amount of water vapour the atmospherecanhold depends upon the temperatureofthe air thehigher the temperatureofthe air the higher the capacityof it to hold water . COMMON WAYS OF STATING WATER VAPOUR (HUMIDITY ) (I) Absolutehumidity Thisis theactualamount of water vapour in a specific volume of atmosphere i.ethe massof water vapour per cubic unit of air and it is normally expressed in g/m3 (II) Relative humidity Thisis theproportionof water vapour present in the air compared tothe maximumamount ofwater vapour, possible at the same temperatureand it is usually expressed in percentage.Normallysaturated air hasrelative humidity100%. 5. PRECIPITATION
  • 17.
    Thisrefers to waterthat falls on the earth in liquid or solid forms.Some commonforms of precipitationarerain, snow, sleet and hail. Rain Thisis most commonform of precipitationspread everywhere and it is liquid form.It forms when tiny water dropletsmergetogether around the nuclei to form raindrops.After becoming heavyenough they fall down to the earth surfaceas rain.Rainfallismeasured by an instrument called rain gaugeand the lines which joinall placeswith equal rainfallare called isohyets. Snow Thisis refered to as solid precipitation, which formswhenair cools to below the dew point or freezing point and fall down as icewhile falling the icecrystals mayjoin together toform snow flake. Sleet Thisis a frozen or partly frozen raindroplet; it so often referred to as frozen rain. It is hazardousas it maydestroy crops, bring down power lines and tree branches Hail Thisis caused by super cooling of water particlesina convectionalup shaft .This super cooling formsthe hail stones .These stone vary in size depending on the intensityof cooling by that convectionalcewent. It is more hazardousthansleet. Hail can causecoderabledamagetoproperty and plantssome hail stones weight up to 2.5 Kilogram which mayhit the ground at speed of up to 160 km/hr. All forms of precipitationresult from rising and cooling of air to below the dew point where condensationbegins.Thevisibleeffect here is clouds in order for precipitationtooccur the small dropletsof water in clouds must join together indrops too largeto remainor be sustained in theatmosphere thus they prefer to fall down on the earth surfaceasprecipitation.
  • 18.
    CAUSES OF RISINGOF AIR When air risesthere is less pressureon it at the new altitude.Asa result the temperatureofthe rising air islowered and cools causing that air to descend and becomewarm. The rateof cooling or heating that resultsfrom thisverticalmovement of air (ascending deslending) is called adiabatic rate. For saturated air therateof temperaturechangeis0.6ºc per 100 meters, which forms unsaturatedair rateis1ºc per 100 metersand it is called dry adiabaticrate. CAUSES OF AIR RISING FOR PRECIPITATION The causesof air rising arealso known as the types of rainfall or the factors that influencerainfall. The factorsincluderelief convectionand the water bodies. (i) Orographic or reliefcause Orographic causeofair rising forms orographicor relief rainfall.It forms when air is forced to ascend as a result of relief featuressuch as mountains or plateaus. Wheremoist air reachesthe mountainprecipitationformsand it is called windward sidewhile the other passaway from windward form the leeward side or rainshadow.
  • 19.
    When moist airis forced to rise over a mountainrange,cloudsand rain often occur. (ii) convectionalcause Here air is forced to rise as a result of intense heating thesurfaceair is heated and verticalupshaft toair occur thisprocess is called convectionand it forms convectionalrainsit is common in summer or hot seasons.
  • 20.
    (iii) Frontal orcyclonic cause Wheretwo bodiesof air masses coming from different directionsand with different characteristicsintermsof temperatureand moisturecontent meet, the warmer air will be forced to rise and condense to form precipitation. Thepoint where these two windsor air meet is called front hence frontalof cyclonic rainfall.
  • 21.
    Warm air isforcedto rise when it is under cut by colder air,cloudsand sometimesRain. Importanceof precipitation i. It maylower temperature ii. It supplieswater to streamsand rivers iii. It is a sourceof water watering crops iv. It absorbssolar radiations IMPACTS OF PRECIPITATION. Impactsof precipitationcanbecategorized intopositiveand negative. (i) Development of water bodies: precipitationencouragesthe development of water bodiessuch as rivers and lakes. These areimportant for irrigation, hydroelectricpower generation,transport, supplyof H2O for domestic and industrialuseand fishing.
  • 22.
    (ii) Cleaning theatmosphere. Thefalling drops collect the dust particles and deposit them on thesurface, keeping the atmospherecleanor less polluted. (iii) Temperatureregulation: -precipitationespeciallyrainfall, regulatesthe temperaturesuch that theatmosphereattainsmoderateweather condition rather thanextremes. (iv) Soil development precipitationalsoplays an instrumentalrolein soil development. It encouragestheweathering of rocksand the decomposition of organic matter. Wherethereis high precipitationchemical decompositiontakesplaceeffectively. (v) Encouraging plant growth: precipitationsupplieswater thesurface, which used by plant for growth. Thishas advantageinthe development of Agriculturesincewhereis effectiveplant growth there is positive agriculturaldevelopment. (vi)Soil erosion:thistakesplacewhen rainfall is very heavy. Erosion is more pronounced in the areaswhere the surfaceis bareand sloppy Erosion destroys vegetation, houses, transport systemsetc. (vii) Outbreakof diseases:when thereis precipitationwater borndisease such as dysentery. Typhoid, diarrhea and cholera, aswell malaria arevery common (viii) Floods: Heavy precipitationleadsto theoccurrenceof floods, which in turndestroy crops, houses,kill animalsand people etc.
  • 23.
    (ix) Mass –wasting (massmovement) takes placeas result of the disturbancescaused byprecipitationon the weathered rock particles. Mass movement can destroycrops, kill people and animalsand destroy electricity supply networks as well as causing a lot of damage. (x) Water pollutionis caused by surfacerun – off cover land Flow and foods, which collect variouswaste materialsand emptythem in the water bodieslike rivers. Dams and naturallakes. Some of thepollutants are deleteriouscharmatultohumanhealth. 6. WINDS A wind is air in motionwhich alwaysmove from high pressureto low pressure belts.Wind speed is measured by an instrument called anemometer whilewind directionismeasured bywind vane. During wind movement it causessome balancessuch as temperaturebalance, humidity balanceand pressure balance. FACTORS WHICH ACCOUNT FOR DIRECTION AND STRENGTHOF WIND 1. Pressuregradient
  • 24.
    Variationof pressurefrom oneplace to another due to variationinpressure causeswind to develop and move from high – pressurebelt to low- pressurebelt: the larger the pressuregradient thegreater the winds speed. 2. Coriolis force Thisis theforce due to earth rotation: It obeys theFerrell's law which state that"Anyobject moving freely in the northernhemisphereis deflected to its right whilesouthern hemisphereis deflected to itsleft". Thisforce is called Coriolis forceand the resultant wind is called geostrophic wind. 3. Friction Thisis commonespeciallyup to 900 metersabove the sea level due to mountainsand big valleys, which may reducethe speed and changethe directionof winds. The influence of frictionstronger on sand surfacethan on water. 4. centrifugalforce Thisis theforce due to earth curvatureand thisforce actsoutward whenan air stream moves on a curved courseas in a pressure system with closed or curved isobarsis subjected tocentrifugalforceacting outwardsfrom the center of curvature. WINDSYSTEMS Wind systems arerelated to pressurebelts these windsare called prevailing winds and they are deflected according toferrell's law prevailing windsare those which blow more frequentlythan other wind in a particular region. Among these winds aretradewinds westerly and polar. (i)Tradewinds These winds meet at the doldrum they arenoted for their constancyof force and direction.Theyareterribletropical stormswhich occur at certain season. At the equatorialbelt the air is heated and rises to be replaced by air moving in (winds) from north and south.Theseform north east trade
  • 25.
    winds and southeast tradewinds which obey ferrell's law. (ii)Westerlywinds These blow acrosslatitude35º and 60º to the polar front these winds are characterized byconstant strength and directioninthesouthern hemispherewhile in thenorthern hemisphereand masses disrupt much of their strength .These windsinclude north west and south west westerly (iii)Polar winds These winds areof solid air they are morepronounced in the southern hemisphereand irregular inthe northernhemispheredue to interruption by mountains. (iv)Monsoon winds These are seasonal windsif the pressureof a largecontinent is high the wind will blow out of it to the sea where pressureis low These arecalled ''offshore winds". These winds arecommonduring winter in Asia as inland temperatureis very low while sea temperatureisstill warm and less dense.If the pressure over a largecontinent is low thanwindsblow intoit from the sea where pressureis higher.Thesewindsare called "onsharewinds" and they are commonin Asia during summer. (v)The upper air movement Prevailing windsarenormally surfacewinds not very far from the earth's surface. These systems of wind are of high speed and high altitude approximately1000 to12000 metersabovethe sea level withinthese winds are narrow bandsof extremelyfast moving air known as "jet streams" JET STREAMS Evidences of strong windsin the upper tropospherefirst camewhen first world war, several interwar ballonsblown off- coursewere observed
  • 26.
    travelling at speedin eccess of 200 km per hour. Pilots in thesecond world war, flying at height above8km found east ward flightsmuch faster and their returnwestward journeymuch slower thanexpected. Theexplanation was to and to be a belt of upper air westernizesthe Rossby wave which form a computepatternaround theglobe. FIVE MAIN JET STREAMS ARE There arefive recognizablejet streams, twoareparticularlysignificantwith a third having seasonal importance i. Polar front jet stream (PEJS) Thisoccursin middle latitudesbetween40 and 60 degreesand a height of 9000 – 12000 meter moreor less at the tropopauseinthe hemisphere. The winds form the divisionbetween theferrell's and polar cells which is the boundarybetweenwarm tropicaland cold polar air these winds are responsiblefor giving fine or wet weather on the earth'ssurface. ii) Sub tropicalset stream (STJS) Thisoccursat about 12000 metersand 25 to 30 degreesfrom the equator and form the boundarybetweenthe Hadley and Ferrell cell in effect vortex associated with themid-latitudecell. They have lower velocitycompared to PFJS but follow thewest-east pattern. iii) EquatorialEasterliesset stream (EEJS) Thisis moreseasonal being associated with thesummer monsoon of the Indiansub continent. iv) Arctic set streams(AJS) Thishas been traced acrossAlaska and Canada at about 7600 meters. v) Polar night set stream (PNJS). Thisis recentlydiscovered above the Aretic circleinthe lower Stratosphere.
  • 27.
    LOCAL WINDS. Local windsarecontrolled by the surrounded”terrain”or environment they are not controlled by planetary system of thewinds they are rather diurnal thanseasonal. There windsdo affect animals, plantsand movement of industrialpollutants. LOCAL WINDS INCLUDE THE FOLLOWING 1) Anabatic and Katabatic i) Anabatatic winds These are cold local windswhich blow from, the valley buttonup to the hilltops. They blow in the afternoonespecially in summer. During the day
  • 28.
    the slopes exruince.Low pressuredue to direct sun rays which makethem hot and windsmove from buttonupwards. They further condense and come down causing thebecomefoggy. There winds are called Anabatic winds. ii)Katabatic winds. These are cold local windswhich blow down from hilltops they occur during thenight where air is rapidlycooled by terrestrialradiationonthe upper slopes. During the night thevalley slopes becomevery cold as they lose the heat rapidly, hence high pressure on them. Due to convectional currentsthevalley buttom becomeswarm creating low pressure. Winds sink down through the valley slopes and rise up from thevalley buttom . These winds arecalled Katabolic winds.
  • 29.
    2) Land andsea braze. During the day land becomeswarm morerapidlythanthe sea. Thus winds tend to move from the sea breeze. During the night theland cools more rapidlythansea. Thus wind tends to move from land to the sea thisactionis called land breeze. Day
  • 30.
    3) Descending winds: Thesewinds aremostly warm and they arecalled Fohn. The nameFohn is
  • 31.
    commonin Alps MountainsofSwitzerland.Whereduring winter theFohn winds descend from the SwissAlps into Switzerland.  During the sameperiod cold winds blow from Francesouth ward torwardsMediterraneanSea. These windsare called "Mistral" but in USA thesame winds arecalled "chinook". Thissituationoccurs mostly in the leeward side of the mountain. Somelocal windsblow from the high pressureover the Sahara duringspring. Thesewinds are warm, dustyand dry becausethey originatefrom thedesert which is dry. The Harmattan. These are NE windswhich blow from the Sahara acrossWest Africa betweenNovember and March. Thesewinds aredry and dusty becausethey originatefrom thedesert. The windsblow during winter towardstheGulf of Guinea where theland is cold while over Mediterraneansea pressureis low becausethe sea is much warmer thantheland. Berg winds: These are thewinds which originatefrom theplateau of South Africa during winter. At thistimethe high pressure lies over the plateau and it is a regionof descending air the windsblow out toward the South SE and SW.Thosewindsare warmer 4) Adiabatic cooling and warming:
  • 32.
    Thisis thechangeof heatper unit area. It occurswhen air is heated on the ground which makes it to rise as it raisesit becomescool and sinks down. Thisis adiabatic cooling and heating. AIR MASSES Air mass is a largevolume .of air whose temperatureand humidityare fairly uniform and covers all extensiveareassuch as desert and ocean surfacesmoving horizontally at different levels. - Characteristicsofair mass normally comefrom the regionwhere the air masses were formed. These characteristicsareretained bytheair mass may be warm, dry or moist. CLASSIFICATION OF AIR MASSES. Air masses areclassified on thebasisof the sourceregions trajectryand characteristicsof both temperatureand humidity. Onthe basisof temperaturetheycanbe categorized aspolar and tropicalair masses. By combining temperatureand humidityfour maincategoriescanbe distinguished asfollows. i)Tropical continental.(Tc or CT). They originateover the continentsin the low latitudessuch as in the desert. They tend to be warm and dry. But near the equatorialthereistropical equatorialcontinentalair mass, which consistsreasonableamount of moisture. Enough to cause precipitation. A good exampleis tropical continentalair massover the Sahara desert, which iscalled the Harmattan. ii) Tropical maritime (Tm or mT). These originateinthe tradewind belts and subtropicaloceansnear the equator theyare refered to as Equatorialair masses(E) these arewarm and moist such that theyto yield heavy precipitation, thunderstormsetc becauseof being unstable. A good exampleis tropicalmaritimeair masses which originatefrom Atlantic
  • 33.
    iii)Polar continental (Pcor cP): These originatefrom thecold land surfacelike the Arctic and Antarctic regions, including centralAsia,northernCanadawherethey develop in winter. These air masses arevery cold, dry and stablesuch that they prevent theformationof rainshowers. iv)Polar maritime (Pm or mP). These originateover the oceans 50º North and south of the equator they are cool, moist and unstable. They yield heavy precipitationastheymove in land in middlelatitudesand high latitudes. CYCLONES,ANTICYCLONESAND DEPRESSIONS i) What areweather cyclones, anticyclonesand depressions? ii) Explain theFormationof these aspects iii) Explainthe weather associated with them. CYCLONES These are areasof Low- pressuresystem, which originatesontemperature Latitudebetween200 -600 north and south of the equator cyclonesoccur all over theoceans except in northernAtlantic ocean. Theisobarsthat represent a cyclone on a map areclosely spaced and they form a circular shape. Strong wind spiralsor tends to move towardsthe center clockwisein the southernhemisphereand anticlockwiseinthenorthernhemisphere. They also tend to rush upward with strong force called vortex which surround the center of the cynodes. IMPORTANCE OF CYCLONES: The rapid rising air givesto torrentialrainfalland the strong blowing wind causesconsiderabledamagetopropertysuch as crops and buildings. FORMATION OF CYCLONES.(Requiredconditions)
  • 34.
    i) Abundant sourceofwarm moist air of temperatureabout 27ºc tothesea surface ii) Air must blow in ward and riserapidlyto great height to giveclouds of great verticalextent, capableofproviding torrentialrainfall. - A Tropicalcyclonedevelops wherethe air mass brought byto northern and southerntradewindsmeet that is along the inter – tropicalfront. They form; over the oceans as theair masses which have traveled over the oceans have warm moist lower air while the upper layer of air masses tends to be cool and dry. When two such air masses meet one is lifted up over the other the rising air cools its moisturecondensesto provide rainfall(torrential). Tropicalcyclonesmove in a westerly directiononreaching laid they graduallydie act becausethesupply of warm moist air is cut off. Warm sea surfaceof temperature27ºc WEATHER ASSOCIATED WITH TROPICAL CYCLONES Before thetropicalcyclones arrive i)Air becomesvery still ii) Temperatureand humidityrises. iii) Thickcloudsappear or develop
  • 35.
    iv) Windsblow violently v)Dense clouds and torrentialrainfallreducesvisibilitytoa few meters Examplesof tropicalCyclones aretornadoes, Hurricanesand typhoons. TORNADO Thisis a small cyclone that appearsasa blackfunnel cloud, hanging from high clouds. Its color is a result of themoistureand debrisbeing carried by wind at a speed of up to 400km/ hr on the ground. It covers a small area of about 90 – 500 metersin diameters - The originmechanism of tornadoesis not properlyunderstood however they are commonlyand mostly associated with theconditionprovided by the meeting of cold, dry and hot moist air. - Thus they are associated with cold front originatedwhereturbulence along therefronts is greatest. Most occur in the USA and are concentrated in the centralstateof OKLAHOMA. HURRICANES These occur in West Indies islands in the Caribbean. Thewind is generally very slow. They have similar characteristicswith typhoonsbut the only differenceis intensitydurationand locality - Weather associated with hurricanes: .Calm dense clouds and stormyweather . Rainless/ dry weather. TYPHOONS: Typhoons occur in China. They are most frequent from July to October and violence is common.
  • 36.
    They have verysteep gradient and cover an area of 30 to 300 kilometersin diameter. Theyoccur around 20o- 60o north and south of the equator. - Weather associated with typhoons  Over cast sky  Torrentialrainaccompanied bythunder and lighting  Verydestructive toboth humanand property. For example 50000 people were killed in 1922 on thecoast of china. ANTICYCLONE Thisis an area of high pressure which when shown on the isoline map, has an oval circular shapeofclosed isobar. Notethat, the highest pressureis near the centre. An anticyclonedevelops in a regionwhere the air is descending and the winds associatedwith it blow outwardsin a clockwise directionintheNorthernhemisphereand anticlockwiseinthesouthern hemispherein West Africa during thedry season anticyclonecover the Sahara and theyare associated with the Harmattan. WEATHER CONDITION ASSOCIATED WITH ANTICYCLONES. Anticyclonesareassociated with thefire weather, calm air and high temperatureinsummer but low in winter and clear skies. During winter intense cooling of the lower atmospheremayresults in thickFog. DEPRESSION These are largeareas of low pressuredue to meeting of warm equatorial and cold polar air. They areoval or circular shared on mapswith closed isobars. Air of depressioncirculatesanticlockwisedirectioninthe Northern hemisphereand a clockwisein the southern hemispherewherethey blow towardsthecenter. - Depressions mainlydevelop in temperaturelatitudeswhenhumid tropicalair meetswith cold polar air especially around; latitude60º north and south of the equator wherewesterly winds meet with polar winds. The
  • 37.
    zone or boundarywherethese windsmeet or converge is called "polar front” it is in thiszone where depressionsform. - Depression arerarely stationaryand theymove in a generale.g. sterly direction. Somearesmall: others arelarge, but all of them are associated with unsettled weather usually with overcast skies and periodsof continuousrain. - The rain is caused by the uplifting ofthe warm moist tropicalair bythe cool drier polar air, as they meet or converge at the polar front. Such rainis called “depressionRain" and it is generally lighter thanconvectionalrain and has longer durationup to several days. WEATHER ASSOCIATED WITH DEPRESSION. Depressions areassociated with clear sky except the circuscloudswhich are little bit high, winds blow from the south east, after a definitetime, a clouds cover develops and heavy rainoccursand the warm front then passes, when the rainstops wind directionchangesand start blowing from south west. Temperaturerisesand thereoccursmore humid air. HYDROLOGICAL CYCLE (WATER CYCLE)
  • 38.
    Hydrologicalcycle (water cycle)refers to the endless circulationofwater from the surface(rivers, lakes, oceansand vegetation) intothe atmosphere through evaporationor transpirationand thenbackto the surfaceasrain, snow, hail or another form of precipitation. Theprocessesinvolved in hydrologicalincludeevaporationor transpirationcondensationafter cooling and later precipitationthecombined processof evaporationand transpirationisknown as evapo –transportation At first water, getsinto theatmosphereas water vapour through evaporationfrom the surfaceor transpirationfrom parts. Later as most air rises, it cools through expansion, leading tocondunsation through condensationwater dropletsor dropsare formed which later fall onto the surfaceas precipitation. Aswaterfallsonto the surface, some of the water in filtratesand percolatesintothe ground to form underground water. Someflow on the surfaceas surfacerun – off (overland flow) or stream flow into the oceansor lakes. Someis evaporated backintothe atmospheretodrive forth the process of hydrologicalcycle. In the process of hydrologicalcycle,insolationis very important sinceit providesthe energy that facilitatesevaporationprocess.
  • 39.
    The diagram aboveshowstheprocess which lead to theformationof precipitationwhich arepart and parcelof the hydrologicalcycle. These processes includeevaporationor evapo-transpirationcooling condensation and precipitation CONDENSATION. Condensationis the processthrough which the atmosphericwater vapor is converted into liquid asa result of cooling. If the temperatureisbelow the freezing point condensationcanbe skipped.Theprocessin which water vapor changesdirectlyintosolid statewithout passing through liquid state is called "sublimation". Theterm also applied when the changetakesplace from solid stateto water vapor without passing through theliquid state when the temperatureareextremelyhigh. WAYS IN WHICH AIR COOLS:
  • 40.
    There areseveral waysthroughwhich cooling in theair takes placeand these canbe identified asfollows. i)Directionradiationofheat energy from the surfaceleads to the cooling of the air, since heat energy is lost into the atmosphere. Theloss of heat energy makesthe surfacebecomecold hence influences the temperatureof air above it. ii)Horizontalair movement over the cold surface(advection) mayalso lead to the cooling effect. iii) Also cooling cantake placewhen warm air mass meetswith cold air mass on mixing along the the front,thetemperatureofwarm air declines, leading to cooling. iv)Another way through which air tendsto cool is by the ascent.The ascending air cools adiabaticallyasresult air massexpension. CONDITION FOR CONDENSATION TO OCCUR Condensationis determined byseveral factorsthat includecooling, presenceof microscopic particlesand presenceof water vapor. i)Atmosphericcooling. The cooling of the atmosphereoccursthrough variouswayswhich include contact with thecold surfacesmixing ofair masses or through mechanical uplift. ii)Existenceofwater vapor When the air saturated, anyadditionalmoistureintheatmosphereleadsto Condensation. iii)Presenceeof microscopicparticlesinthe atmosphere. Theseact as condensationnuclei which providethe starting point for condensation. Water vapor molecules tend to collect around the particlestoform water droplets when the particlesareabsent, condensationtakesplacewith difficultyunless the atmosphereissuper saturated.
  • 41.
    COMMON FORMSOF CONDENSATION. Condensationmanifestsinvariousform namely  Dew  Frost  Clouds  Fog. Dew Dew consists of water dropletscondensed and deposited on the cold solid surfaces. It usually Forms during long nightswith clear skies having little or no wind when the atmosphereisrelatively moist.Whenthesky is clear there occurshigh rateof outgoing radiation, which inturnleads to the cooling of surface. Frost Is the term used of meandew that becomesfrozen. The conditionthat favor itsformationarethe same those. For formationof dew except the condensationoccursunder freezing point.Desert and semi-desertsare places wheredew and frost commonoccursat night, since these areascan sometimesexperiencelow night temperatureaslow below O0C. Log and mist,Haze. Fog and mist areclouds at ground level, which result from moisture condensationand they may extend far in the atmosphere.Fofand Mist differ in visibility. Mist forms wheremoist air cools below dew point. Condensationtakes placebut theresultant water dropletsremainsuspended in kilometers. On the other hand Fog is like mist and forms in the sameway but it is much denser as it reduces visibilitytoless thana kilometer. There arevarious types of fog depending on their mode of formation. TYPES OF FOG i)Advection Fog: Refers to Fog caused by the cooling of warm moist air. Transported over the
  • 42.
    cold surface. Also,advectionFog can be caused by the cold air passing over a warmer sea surfacethan mixeswith thewarm air prevailing there. ii)Radiation Fog Thisoccurswhen land surfaceis suddenly cooled by radiationwheretheair upon it becomes chilled which results into condensation. It commonin hilly areas. iii)FrontalFog Thisforms due to passageof warm air over cold air. The warm air is thereforechilled to form Fog.It forms at the Front of depression. iv)Upslopeor expansion Fog chill Fog Refers to the Fog formed when the air-massmoves upslope leading to adiabaticcooling due to air mass expansion. It forms simplelow sheet cloud which mayenvelop the hills like, what happenson the hills of western. Britainwhenmoist air is moving on land v) Steam Fog Is the type advectionFog formed when a cold air- mass passesover much warmer water surfacesuch that water appearsto"steam" In latitudeit is referred to as ice-Fog. Wherethe moistureinthe air is converted into ice crystals, steam Fog is rare and does not last for a long period of time. vi)Sea Fog Is formed when thesea air cools over thecold ocean currents. It differs from the steam Fog,inthat the sea Fog does not appear assteam but just as normalFog. Also in steam Fog, themoving air is cold and stableand warms over thewarm water surface. vii)Smog Fog Thisis Fog plus smoke and industrialpollutant likeCO2, CO and SO2 it is usually yellowish in color and acidic insmell,smog is commonin big cities e.g. Ruhr industrialarea inGermany. Fog has major environmentalhazards particularlyon transportation. viii)Rime When a Fog composed of super cooled droplets is driven by slight wind against prominent objectssuch astelegraph poles, wiresand treesthe drops freeze on them as rime. The temperatureofboth droplets and the
  • 43.
    objectsis below freezingpoint. The rimehasthe white, opaque appearance. Thisis a commonfeatureon the mountainsof Britain. CLOUDSAND CLOUDSFORMATION Cloud is another element of weather. It is defined as a mass of water vapour which hangsin the sky. Clouds are a form of condensationwhich consistsof water dropletsor of tiny icebar tidesfloating at various levels from the ground to the very high altitudes. At 12000m abovethesea level. - Mist and Fog aremade of water dropletsand in this repast theyare types of cloud, but they form near the surface. - The clouds give hint on thetype of weather that islikely to occur through their shape, height and and natureof movement. Thus they are carefully studied by meteorologistsinorder to prepareweather forecast and variousprecautionaryinformationonthe impeding weather phenomena. On the map cloud cover can be represented by using the lines. CLASSIFICATION OF CLOUDS There aremany different types of clouds, but they areoften difficult to distinguish astheyform constantlychanges. The general classificationof clouds was proposed by LUKE HOWARD in 1803 this classificationis based on form appearanceand height and he used four Latin words cirrus, cumulus, stratus and nimbus. - High clouds (6,000 to12,000m) - Middleclouds (2,100 to 6,000m) - Low clouds (below 2,100m) a) High clouds 6,000 – 1,200m (consistsof cirruswhich start with cirro.) i) Cirrusis composed of small icecrystals, wispy, fibrousor feather. Its a appearanceisminbandsor patches.
  • 44.
    ii) Cirrocumulus –iscomposed of ice crystals:” globular or ripplelike in appearancelookslike ripplesor wavy structuresinthe sand on a sea shore) Forming a thincloud. iii) Cirrostratus- it looks like a thinwhite, almost transparentsheet that gives the sun and moon haloes. b) Middleclouds below 2,100 - 6,000m (consistsof clouds whose names start wish acto) i) Altocumulus – is composed of water dropletsin layers or patches globular or bumpy. Looking with Flattened based arranged inline or waves. Thisindicatesfair weather. ii) Altostratus –is composed of water dropletsforming sheets of grey or water looking clouds, partlyor totally covering the sky. c) Low clouds below 2100m. i) Stratocumulus: isa largeglobular mass: bumpy – looking soft and grey in appearanceforming pronouncesregular patten. It is in fact darker, lower and a heavier type of actocumuluscloud. It always allows the penetrationofsome our rayscalled crepuscular rays. ii) Stratus –is fog- like low cloud forming a uniform layer: brings dull weather and often carom paled by drizzle. iii) Nimbostratus –Darkgrey and rainy – looking dense and shape less often gives continuousrainclouds of great verticalextent. iv) Cumulus: round topped and flat based forming a whitish grey globular mass consisting ofindividualcloud units. v) Cumulonimbus – is a lowering cloud which is usually whiteor blackappearing as globular masswhose rounded tops often spread out forming an anvil structure. It is associated with convectionrainlightingand thunder. This cloud is sometimescalled "thunder head".
  • 45.
    NB: Cirrusand curriform cloudsoccupyhighlevel and form high clouds; clouds that start with actoarefound in the middlelevel constituting middle clouds. Nimbusisthe term that appliesto rainbearing clouds; stratus appliesto clouds that form layers or uniform cover and cumulusis the term used for clouds that occur in a massivenature. Clouds at different levels and extent
  • 46.
    The Amount ofcloud cover is estimated inoktas; one oktasrepresents one – eighth of the sky covered with clouds. WEATHER CHANGES ATMOSPHERIC STABILITY AND INSTABILITY Atmospheric stability The stateof stabilityiswhen a rising parcelof unsaturated air coolsmore rapidlythanthe air surrounding it. If thereis nothing to force the parcelof air to rise such as mountainsor fronts it will sink backto itsstarting points. The air is described asstablebecausedew point may not have been reached and the only clouds which might havedeveloped would show flat topped cumuluswhich do not produceprecipitation. Stabilityisoften linked with anticyclones. - Absolutely stableis experienced whenthe ELR is less than theSALR (SaturatedAdiabaticLapseRate). During absolutestabilityeven the saturated air, which isusually buoyant (light), tends to cool faster that the surrounding air and keeps on sinking rather thanrising. Stabilityisalso called stableEquilibrium. Atmospheric instability: Conditionsof instabilityariseinon hot days when localized heating of the ground warmsthe adjacent air byconductioncreating,ahigher lapserate. The resultant parcelof rising unsaturated air coolsless rapidlythanthe surrounding air. In thiscase the environmentallapse ratelies to the left of the Dry Adiabatic LapseRate, therising air remainswarmer and lighter thanthe surrounding air. Should it be sufficientlymoist and if dew point is reached, then the upward movement may be accelerated toproducetowering cumulusor cumulonimbustypeclouds. Thunderstormsarelikely and saturated air following the release of latent heat,willcool at the saturated Adiabatic lapse rate. CONDITIONAL INSTABILITY. Thistype of instabilityoccurswhentheELR is Lower thanthe DALR but higher thanthe SALR. It is the most commonof the three conditions.
  • 47.
    The rising airis stablein its lower layers and being cooler thanthe surrounding air would normally sink backagain. However if themechanism which initiallytriggered theup lift remains, then the air will be cooled to its dew point. Beyond thispoint cooling a slower SALR and the parcelmaybecome warmer thanthesurrounding air. It will now continue to raisefreely even if the uplifting mechanismis removed as it is now in an unstablestate. Instabilityisconditionaluponthe air being forced to risein the first place, and later becoming saturated sothat condensationoccurs. Theassociated weather is usually fine in areasat altitudesbelow condensationlevel but clouds and showery in those above. - What tonote is that Unstableair mass is regarded tobe either conditionalor potential.It canbe conditionalifafter it has reached dew point it cools very slowly to retain warmnessthat the surrounding and forced to rise higher and higher. - It is regarded tobe potentialifthe conditionair is forced to rise above cold air mass. Atmosphericinstabilityisassociatedwith relativefall in temperature, high humidity(dampness) heavyclouds, sand, heavy rainfall. These conditionscanbe summarized asfollows: Stabilitywhen ELR< DALR or (DALR> ELR) Absolutestabilitywhen ELR< SALR or (SALR >ELR) NeutralEquilibrium when ELR = DALR or (DALR =ELR) Absoluteinstabilitywhen ELR > DALR or (DALR < ELR) Conditioninstabilitywhen ELR is betweenDALR and SALR.  Diagramsrepresentingatmosphericstabilityand instability.
  • 48.
    In diagramabove. The linefor DALR is below the line for ELR. Indicating thattheDALR is greater thantheELR and thereforethe air is cooling faster thanthe ELR leading at atmospheric stability. Inthis casethere is no verticalair – mass movement since the cold dense air mass tends to sink down to the surface.
  • 49.
    In the diagramabove: the line for SALRis below theline for ELR indicatingthat theSALRis greater thantheELR and thereforethe saturated air iscooling faster than the ELR Leading to atmospheric stability. Alsoin this casethe verticalair- mass movement is limited, sincethe denser air masstends to sink down to the surface. In the diagramabove, theELR is below the line for DALR indicating that the ELR is greater that theDALR and thereforethe dry pocket of air is cooling at a lower ratethanthe ELR, Leading atmospheric instability. Also in thiscase, the verticalair – mass movement is pronounced since the pocket air mass tends to risebecauseof buoyancyor lightness. Under this situation, thesecanbe condensation, freezing and precipitationinthe atmosphere. Stormsalsodevelop, affecting theearth's surfaceand its variousfeatures.
  • 50.
    In the abovediagram: One can find that beforecondensationis thelower altitude, theair is dry and DALR is greater thantheELR. The atmosphereexperiencesstability. As air is forced to risethe cooling processleads to condensationwhich saturatestheair. The saturated air becomeswarm due tothe additionof moisturewhich haslatent heat. It then startsrising spontaneouslywhile cooling at the SALR, which is lower thanthe ELR. This situationmanifests the attainmentofa stateconditionalinstability. CAUSES OF AIR – MASS ASCENT. Pocketsof air areforced to rise several ways, which include;
  • 51.
    i) When theair- massis heated or warmed by conduction, air risesin conductiontheheat energy which is reflected from the earth’ssurface warmsthe air resting above; then verticalconvectionalcurrentssetsup. Thisphenomenon leads to the formationof convectionalrainand it is commonin the equatorialand tropicalareas. Theconvectionrainfalls in the afternoonand is usually accompaniedbyrainfalland thunder. ii) The pocket of air can riseafter being forced mechanicallytorise up the slope incasethe wind blows against themountainside. The air massthat rises cools leading to condensationand later the formationoforographic rain, which is commonin mountainareaslike Kilimanjaro, Uluguru, Rungwe, Meru and Usambara inTanzania.
  • 52.
    iii) Thethird wayinvolves the situationwhereone air – mass, usually warm is forced by another massof air which is usually cold. The warm air rises above thecold air creating a zone of contact inbetweenthem called front. In most cases of raising air a verticalelement is introduced which isa form of convergent rotation. Under thissituationa depressionis usually created, which isassociated with law pressure formationofclouds and rainfallformation. It should be noted that when the air-massiswarm, it tends to expand and it always lighter, such that it keeps on rising above. TYPES OF TEMPERATURE INVERSIONS a) According tothecauses, temperatureinversionscanbe categorized into four types namely : - Subsidenceinversions - Advectioninversions - Radiation(nocturnal) inversion - Frontal inversion
  • 53.
    i)SubsidenceInversionis formed wherethe air is descending in the high pressurezones. The sinking of the air leads to compression, which in turn causestemporaryinversionat a higher level in the atmosphere. Thistypeof inversion is also called high inversion and usually last a long time. ii) Advectioninversion is caused by a warm air massadvancing acrossthe cold surface. The lower portiongets cold while the upper part remainwarm thiscan happenover thecolder sea in summer or over the land massin winter. iii)Radiation(nocturnal) inversionisthe type of inversionthat occurs during night when the land is very cold becauseof having lost most of the heat energy through radiation. Nocturnalinversionoccursexclusively over the land as the ground cancool much more quicklyafter sunset, thanthe sea. It is also called ground level inversion as it is near the surface. This type of inversion disappearswhenthe sun rises in the Morning. vi) Frontal inversion which occursasa result of the formationofwarm and cold front due to meeting of two air masses. Thewarm air rises over the cold air mass keeping the atmosphereabovewarm whilenear the surface. b) According tothelevel of occurrence:According tolevel of occurrence temperatureinversioncanbeclassified as ground level and high level inversions. i.Ground level inversion is the type of inversion that takesplace near the surfaceof the earth due to cooling, caused by the lose of radiant energy into thespace. The air near the surfacetends to be cooler thanthe air above it. Sinceit is in contact with thecold surface. It takes placeat night and disappearsinthe morning whenthe sun arisesNocturnalinversionis good.Example;
  • 54.
    The above hypotheticaldiagramindicatesthattemperatureinversiontakes placenearthe ground level due to the influenceof surfaceradiationsuch that as one moves from 0 to 45 meters abovethe sea level will experience the rise in temperature. After 45 metersof altitudethetemperaturestarts decreasing at a normal lapse rate. ii.High level temperatureinversion Takes placeat upper levels of the atmospherefor example, after 145 meters above the sea level . It canbe caused by air subsidencepresence of water vapour or a layer of Carbondioxideand Ozone. It is usually last longer than
  • 55.
    the ground leveltemperatureinversion. iii.Theabovehypotheticaldiagram illustratesthat from 0 to 145 metersis above the sea level the temperaturedecreaseswith altitudeat a normal lapse and after 145 metersit tends to increasewith increasein altitude(temperatureinversionoccurs). ATMOSPHERE Thisis thethis layer of gasesheld on the earth by the gravitationattraction. Composition of atmosphere Describeand explainthe compositionof theatmosphereatmosphereis composed of the following;
  • 56.
    i. Mixtureofvariousgases theseincludedoxygen21% nitrogen78% Argon 0.09% and Carbondioxide0.03%othersincludeneon, xenon, krypton helium and others in minutepercentages ii. Dust particledust particles maybe naturalor artificialwhere naturaldust particlesarethose caused by wind and volcanic eruptionwhile arterialdust particlesarethosederived from industrialpollution iii. Water vapour thisis colourless, odourless gas in form of water which makesup a perfect mixturewith gases. The degreeat which water vapour is present in the atmosphereintermed as humiditywater vapour condenses in term of rainsnow, mist excess water vapour bringsabout capitationinform of rainsnow, sleet and hail when water vapors is present in the atmosphereinsmall quantityextremedrynessof air many cause occur of hot desert. THE STRUCTURE OF ATMOSPHERE Atmosphereisdivided into layers according totemperaturetheselases are i. Homosphereand ii. Heterosphere A. HOMOSPHERE Thisis thelower part of atmosphererunning from 0-80km above the sea level. Thislayer has there sub layers which areTroposphereStratosphere and Mesosphere. 1. Troposphere Thisis thelowest part of homospherefound between 0-9milesor 0-15km above sea level, the layer is composed of gases water vapour and dust. All processes of rainformationtakeplacein this zone and temperature decreaseswith altitudeat a normal lapse rate. The lapse ratein Troprosphereis 0.6 ºC per 100 metreswhich is equivalent to 6.5ºCper 1000 metresrise. The lapse theresult of thefact that the earth'ssurfaceis warmed by incoming solar rotationwhich inturnheats theair next to it by conduction, convectionand radiation. Thetropopausewhich formsthe
  • 57.
    upper limit toearth'sclimateand weather is marked byan isothermallayer where temperatureremainsconstantsat -80ºC. 2. Stratosphere Thisis thesecond part of homospherelying above tropopausebetween48 kilometresabove the sea level. Much of the zone layer is concentratewithin thiszone particularly15 to50 kilometresabove the earth’ssurface. Sometimestheterm ozonesphere is used to refer the layer where there is concentrationofozone gases. Temperatureremainsunchanged with increasing height at tropopausebut later it start to increasewith height the lower stratospherecover about 15 to25 kilometrefrom the earth'ssurface thisis the layer in which temperatureremainconstant. Thissteadyiscase in temperature(temperatureinversion) iscaused by concentrationzone (O3) thisgas absorbsincoming ultra violet (UV) radiationsfrom sun. The stratopausewhich markstheupper limit of thiszone is other isothermal layer where temperature doesnot changewith increasing height. 3. Mesosphere Thisis thethird part of homosphere lying abovestratopausebetween48to 80 kilometersabove the sea level where temperaturedecreaseswith altitudeup to -100ºCat 80 kilometersabove the sea level. Temperature falls rapidlyif thereis no water vapour, clouds, dust particlesor ozone to absorb incoming radiations. Thusthislayer experiencestheatmosphere lowest temperatureand strongest wind. Themesopauselike the tropopause and stratopausewhich istheupper limit of this zone records theminimum temperaturethatmayfall to -100ºC and thus shows no further changesin temperature. B. HETEROSPHERE Thisis is thesecond zone of atmospherewheretemperatureincreaseswith altitudefrom -100ºC at 80 kilometresto about 500ºCat 8o-5,000 kilometresabove the sea level. The increaseof temperatureisassumed to be so becauseof lack of water vapour and dust particleszone. The upper part of this zone is called Ionosphere which is sometimesdivided into exosphereand thermosphere. In the thermospheretemperaturerises rapidlywith height perhapsto reach 1500 ºC . This is due to an increasing proportionof atomic oxygenin theatmospherewhich like ozone layer absorbsincoming Ultra Violet radiations.
  • 58.
    TEMPERATURE INVERSION Temperatureinversionrefersto theincreaseintemperaturewith height above the earth’ssurface. Thisphenomenon is a reverse of the normallapse ratein the atmosphere; it isthe exceptionallapserate. This situationof increasein temperaturewith altitudeiswhat called reverse lapse rateor abnormallapse. In temperatureinversionit meansthat, temperatureinthe air far abovethe ground. CAUSES OF TEMPERATURE INVERSION I. Presence of ozone layer in the atmosphere Ozone in the atmosphereabsorbsenergyfrom the sun especially ultra violet(UV) rays. The reactionbetweentheserays and ozone gives out heat whit warmsthe atmospherefrom the ground surface. II. Formation of fronts Thistakes placewhen twoair masses of different temperaturemeets. On meeting thewarm air rises above the cold air. Under thissituationtwo fronts areformed such that thewarm front is aboveand the cold air leading to temperatureinversion. III. Air subsidence When thereis high pressure air tends to descend or sink down. The downward of air leads to compressionor frictionbetweenmolecules thus creating warm conditioninthelevel. IV. Atmosphere components Water vapour and dust particlesat a higher level, keep the atmosphere warmer thannear the surfacesince it preserves energy from the sun for a longtimewhich leads to temperatureinversion. V. Advection When the massof warm air passesover the cold surfaceitslower part is cooled by the cold surfaceleaving the upper portionwarm becauseof being far awayfrom the influenceof thiscold surface. VI. Radiation
  • 59.
    Radiationofinfra red energyfrom the earth'ssurfacemakesthe ground cool very quickly. The cold surfacecools the air immediatelyaboveleaving the other layer far above warm. For example; during clear settled weather, as radiationofheat takes placeduring thenight the air on hill - slopes is rapidlycooled and thusdense air drawndown wardsfilling valleys or basinswith cold air possibly at temperaturebellow freezing point, when the upper slope are markedlywarmer. VII. Water vapour Water vapour at higher altitudeskeepsthe atmospherewarmer thanair the surfacesince it preserves heat energy for a long time. Thisalso causes temperatureinversion. EFFECTSOF TEMPERATURE INVERSION 1. The warmer layer of air above the cold air may lead to increasein atmospherestabilityand verticalair mixing assuch the temperatureis always calm with no precipitation. But when inversionoccursdue to the development of precipitationand formationof cyclonic storm. 2. Temperatureinversionleadsto the formationof fog and smog. Smog is commonin the industrialized areaswith a of smoke which is produced from industries. Thesmoke so produced mixeswith fog to from smog. 3. Air pollutiontakes placewhen there is temperatureinversion.Theair is polluted becauseof the sinking of particleswhich arehanging inthe atmospheredue to the fact that the warm air abovethe cold air is less dense and thus not capableof holding the particlessincethey aredenser thanthe warm air. The sinking down of air to the lower atmospherelevel causesair pollution which affect humanhealth, animaland plants. It can causeitching of body, inflammationofeyes and coughing. THE HEAT BUDGET The sun's energy is called insolationor solar radiationwhich turnsintoheat energy at the earth surface. Insolation travels through spacefrom the sun inform of waves and interact with outer edgeof atmospherebeforereaching the earth'ssurface. Totalamount of solar radiationreleased from the sun is 100% sincethe earth is neither warming up nor cooling down, therebe a balancebetweenincoming insolationand outgoing terrestrialradiation. The atmospheric conditionthereforereducestheamount of solar insolation
  • 60.
    through threeprocesses; 1. Byabsorption: About 15% of totalsolar radiationisabsorbed inthe atmospherebythe atmospherecomponents. Thegreater absorbersare water vapour, dust particlesand clouds. 2. By reflection: Certainamount of solar radiation isreflected backinto the spaceby clouds, dust particlesand ground. The amount of insolation reflected depends on the surfacebut the averagereflectionamountsto40% of totalinsolation. ALBEDO Albedo refers to the percentageexpressionofthe ratiobetweencoming radiationsand theamount reflected. Clouds and to a less extent, the earth surfaceare theprincipalreflectorsof the incoming radiationsbackinto space. The albedo varieswith cloud type from 30-40% inthinclouds, to 50- 70% in thicker stratus and 90% incumulonimbuswhereonly 10%
  • 61.
    insolationreachesthe atmospherebelow thecloud level. Albedo also varies over different land surfacefrom less than 10% over oceans and darksoil, for 15% over coniferousforest and urbanareas25% over grassland and deciduousforests40% over light coloured desertsto 85% over reflecting fresh snow. Thisreducespossibilityat icemeet and disappearson mountaintopslike Kilimanjaro. THE OZONE LAYER The ozone layer is found withinthe stratosphereand it sometimesre- termed as a shield of life. The layer is highly concerned with humanand all other earth life and it sets in at an altitudeof about 15km and even upward to about 55 kilometers. Thislayer serves as a shield protecting the troposphereand the earth surfacefrom most violent raysor radiationfrom the sun. If these rays were to reach the earth directly, all bacteriaexposed would be destroyed and animaltissueswould be damaged.Destructionof thislayer by some scientific discoverieshasmadetheintensityof ultra violet rays reaching theearth surfaceto increasecausing globalwarming. If thissituationisleft to continue, it will causesuffering particularlycancer , crop reductionin yield and killing of organismson land, water and air. FUNCTION OF ATMOSPHERE 1. It is an insulator: It moderatestemperatureduring night winter. 2. It is a filter: It filters solar insolationthrough ozone layer and provides a layer through which meteorsare burnt intogases. 3. It is a scientific field whereradio, radar, televisionand other communicationincluding air transport and telephonesare done. 4. It has hydrologicalfunctionwhere rainfallis formed. 5. It support itslife through breathinginanimalsand respirationin plants. CLIMATOLOGY Climatologyisthe studyof climatethat dealswith spatialdistribution atmospheric phenomena. It mainlydeals with definitionand descriptionof different climatesintheir geographicalsettings.
  • 62.
    Meteorology isthestudy ofweather. It is a scientific studyofthe physical process constantlyat work in the atmosphere. It is highly applied in the forecasting ofthe futuretrend of the weather. It is a branch of Science which deals with the conditionsof or withinthe atmospheresurrounding the earth. Climatologyand meteorology arethe studiesor thesciences which are concerned with the study of atmosphereand its elements like weather and climate. CLASSIFICATION OF CLIMATES By studying theweather, the atmospheric conditionsprevailingat a given timein a specific placeor area; it is possible to makegeneralizationabout the climateof that placeor area basing on the averagenormalcondition over a period of timeusually 35 years. In seeking a sense of order; the Geographerstryto group together those partsof world that have similar measurableclimatic characteristicsintemperature, rainfalldistribution winds, etc. Classificationofclimateisdone in different systems.  Greek’s classificationsystem.  Germanyclimatologist classificationsystem.  Koepen's temperaturezones classificationsystem.  Miller'sclassificationsystem. GREEK CLASSIFICATION SYSTEM The early Greeks divided the world intothree zones based upon a simple temperaturedescription. A classificationofclimatebyGreek is based on temperaturecontrolofthe climateand they completely ignored precipitation. Under thisapproach climateisdivided into: i) Tropicalclimatewheretheamount of temperatureishigh. ii) Temperateclimatewherethetemperatureismoderatei.ebetweenthe tropicaland polar temperaturecondition. iii) Polar climatewherethe temperatureisextremelyLow. KOPPEN’SCLASSIFICATION SYSTEM
  • 63.
    In 1918 Koppenadvanced themodern classificationofclimate. To support his claim that naturalvegetationboundariesweredetermined byclimate, he selected as his basiswhat he considered were appropriatetemperature and seasonal precipitationvalues. The classificationofclimateby thisapproach isbased on the duration above or below the value belt. By thisapproach climateisclassified intothe following belts;  Tropicalbelt The climatehaving 12 months with temperatureabove20oC.  Sub- tropicalbelt The climatehaving 4-11months with temperatureabove20oC.  Temperaturebelt The climatehaving 4 – 12 monthswith temperatureranging from 10oC– 20 oC.  Cold belt Thisinvolves those areashaving 12 monthswith the temperature ranging from 10ºCto 20ºC.  Polar belt The climatehaving 12 months with temperaturebelow 10oC. CLASSIFICATION BY GERMANY CLIMATOLOGIST According toGermanyclimatologist, climatedivided intothefollowing types;  Hot zone climate The climatewith temperatureisothermof20oC annually.  Cold zone climate The climatewith annualtemperatureisotherm of10ºCor below.  Temperaturezone The climatewith temperatureisotherminbetween10oC – 20oC.
  • 64.
    MILLER’S CLASSIFICATION SYSTEM InBritain, inthe 1930s, Miller proposed a relatively simpleclassification based upon five latitudinaltemperaturezones which he determined by using just threetemperaturefigures. Thisisthe most popular method of climateclassificationtodaybecauseit combinesboth mapsof temperatures, showing temperaturebymeansof isothermsand map of rainfallshowing rainfallby meansof isohyets. It shows a close relationship to vegetationzones and thisit is easier to use and convenience. - The structureofclimateclassificationisasfollows;  Hot zone - With temperatureabove20oC.  Warm zone - With temperatureranging from 10oC – 20oC.  Cool zone - With temperatureof 10oC.  Cold zone -With temperaturenear to0oC .  Arctic zone -With temperaturenear to0oC and below. CLIMATIC FEATURES  Dry warm summerswith offshore trade winds.  A concentrated rainfallin winter with offshore westerly.  Bright sunny weather with hot dry summer and wet mild winter.  Presenceof local winds around the MediterraneanSea e.g. moroccoand Muscat.  Annual rangeof temperatureishigh about 11ºC  Rainfall is moderateabout 838 mm and normally falls during winter and it is cyclonic raintype.  Summer temperatureisabout 21ºCand winter is 10oC, hence high rangeof temperature. VEGETATION Evergreen coniferousforest, Mediterraneanbushesand grassessemi arid shrubsas well as grasses, evergreenMediterraneanforests. ECONOMIC ACTIVITIES: Crop cultivationdue to high rainfall and moderatetemperature, Animal rearing i.e. transhumance(pastoralism) orchard farming with different kind of fruitsand vegetable(market gardening).
  • 65.
    EQUATORIAL CLIMATE Thistype ofclimateoccursasa belt around the world at about 5º North and South of the Equator but it is also found around 5º-10º North and South in some places. The continuityofthis climatehowever is interrupted in several places by mountainssuch as Andes of South America and theEast Africa high lands. DISTRIBUTION OF EQUATORIAL CLIMATE Zaireand Congo basin, Amazonbasin, East Indies, South Ivory Coast, and WesternCoast Nigeria, EasternCoast, Malaysia and North eastern Australia. PROBLEMS OF CLIMATE CLASSIFICATION Classificationofclimateposes moredifficultiessincethereis no clear boundarydue to the fact that climatesareTransitional. Thusall classificationshaveweaknesses, non is perfect because; - They do not show transitionzonesbetween climates, and after the divisionlines arepurely arbitrary. - They do not allow for mesoscale variationsuch asthe lake and district or microscalevariation(localvariation). - They can be criticized for being either too simplistic (miller) or too complex. - They ignorehumaninfluence and climaticchangeboth inthe long term and the short term. - Most tend to be based upon temperatureand precipitationfigures, and neglect recent studiesin heat and water budget, air massmovement and the transfer of energy. - All suffer from thefact that some areasstill lack the necessary climatic datatoenablethem to be categorized accurately. GENERAL CLASSIFICATION OF CLIMATE A: MEDITERRANEAN CLIMATE The warm temperatureWesternmarginor the Mediterraneanclimateis
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    confined in theWesternmarginof continentallandmassesbetweenlatitude 30o-40o North and South of theequator. Areas involved CentralChile, California, CapeTown, SouthernAustria, South West Australia, SanFrancisco, and partsof Morocco. CLIMATE CHANGE It has been noted that a certainarea experiencea certain climaticcondition. Thereforeany deviationfrom the expected conditiondenotesfor a climatic change. There areseveral evidences of climaticchange. Theseinclude; rocks arefound todayin areaswhich seems to have a different climatic conditionunder which they formed, fossil landscape, sea level changes, shifting of vegetationbeltsSahara, etc. CAUSESOF CLIMATE CHANGE For the factorsor causesof historicalclimaticchange, refer to the theories which explainthe iceages. Note: However todaythe world is experiencing theso called “Global warming” Scientistshavereached a consensus on this point of global warming asa published by the InternationalPanelon climatechange (IPCC). Global warming mayrefer to the world wideincreasein the lower atmospheric and terrestrialtemperature. Thismaybe as a result of increase in the concentrationof one or moregreenhouse gases(GHG) as well as the Ozone layer depletion. Global warming ismainlytheory assertsthat the increasing levels of GHG will progressively trap moreof the Earth'sheat, graduallywarming theglobalclimateasmuch as 3 to 9 degrees. However the reasons which have been put forward to explainthe scenarioarerelated to those activitieswhich pump theGHG intothe atmosphere. Therefore manthrough different activitiescarried out for his triggersoff climate change. The Marjoryinclude; CFC’s and Halons: Scientistsfirst suggested in1974 that theworldwide use of CFC’s and halons could be destroying theOzone layer.
  • 67.
    In 1982, Britishscientist for thefirst timedocumented theexistenceof a largehole in the ozone layer over the Antarcticathat had beentheoretically predicted earlier. In thiscase theemitted CFC’s and halon react with the ozone in the stratospheretobe depleted which formally absorbed some incoming radiation. CFC’sis emitted from coolants in air conditionersand refrigerators, propellantsinaerosol spraycans, cleanersfor electronic parts such as computer chips, productionand burning ofplastic foam products. Fossil fuel burning: Like coal burning inindustriesbeforethe introductionofalternativeenergysource; this could emit large amountsof GHG such as carbondioxideand methaneintothe atmosphere. The industrialrevolutionsparked off the extractionof the coalto run the machinesor industrieswhich had sprung up. The perpetualburning meant continuousemissionof carbondioxideand sulphur hence contributing through the greenhouseeffect. Deforestation: Thisinvolve the clearing of vegetationand burning of grassland for either establishment ofsettlement/industriesor agricultural activities. Thisresultsinto the accumulationofcarbondioxidewhich would have been taken up by plants. Cultivation of rice: Thisis couple with the release of methanegasinto the atmosphere. Livestock farming: Animalslike cattleproducemethanegasdue to their microbialfermentativereaction. Thereforethedumping ofcow dung will release too much methaneas it decomposes. Animalhusbandryisthought to be responsiblefor much of the increase. Ozone layerdepletion: The chemicalreactionswhich takeplace betweenthe GHG may breakdown or deplete the ozone layer. Thismakes it thinner or drill a hole making it easier for more insolationto pass through to reach surface. Thereforethe more insolutionreaching theEarth’s surface, the more thetemperaturewillincreasehence climatechange. Industrialization: Someindustriesemit GHG intothe atmosphereto changethe climatethrough thegreenhouseeffect aswell as reacting with the ozone layer. Transportation: Automobileemit carbondioxideduring thecombustion of fuel in the engine which act as GHG to contributetheglobalwarming.
  • 68.
    EFFECTSOF CLIMATIC CHANGE Theeffects we feel or observe are rarely, if ever, the effects of a single factor, they are combined impactsofthe whole of factors(pollutants) acting over the totallife span, and frequentlythe effects are synergistic. For instance both plant and animalsmay be so stressed by climatic changeand become vulnerable to other environmentalfactorssuch as attackbyparasitesand diseases. Given the complexityofthis situation, it isextremelydifficult todetermine the effect of any particular factor. Neverthelesssome significantprogress has been madeto link climatechangeand some effects, these mayinclude; Soils: Higher temperaturescould reducethe water holding capacitiesand increasesoil moisturedeficits. It should be noted that climatechangewill alter the chemical, biologicaland physicalpropertiesofthe soils. The expected temperatureraiseand related prolonged droughtswill increase the rateof soil organic matter decompositionthusaccelerating land and soil degradation. Thiswillescalatesoil fertilitydepletionresult into low productivity. On theother hand, theanticipated floodsin highland areas will acceleraterunoff and soil erosion. Flora and fauna: Higher temperaturesand increased water deficits could meanloss of several species. Thisis becausethe exiting flora and fauna cannot adjust drasticallyto acclimatizetothenew climatic conditions. For instancethe increasing temperaturemayaffect theaquatic animalslike fish which are used to cool/cold environment. In which additiontothat, the changein climatewillchangein the qualityof the different habitatsand consequentlyall the flora and fauna in them. The habitatsmayinclude; wetlands, forests, etc. Agriculture: Agriculturalactivitieswhich entirelydepend on rainfallwill be hit by climatechangesuch as prolonged drought, unreliablerainfallare evident in some areas. Droughtslower the productivecapacityof rain –fed agriculturehencereducing theagroexports, increasing food prices, nutritionaldeficienciesand destabilizethemacroeconomies. Cerealswill be hit by dry seasons hence a reductioninthe productionofcrops. For instanceaccordingtoNAPA (2007), intheLake Victoria basininTanzania, maize productivityisestimatedtoreduceby 17% due to the anticipated
  • 69.
    climatevariabilitymanifestinginform of temperatureraiseandreduction in rainfall. The increasein thenumber of pest and diseases due to climatechangeisa set-backinthe agriculturalactivities. Coastal regions: Rise in sea level, increaseinheight of stormsresult into more flooding especially around estuaries. Flooding affectshousing, industry, farming, transportand wildlife. Flooding increasesthe susceptibilityof water borne diseasesalong lake shores, coastlines, and other placesliable to flooding. For instanceinUganda the outbreaksof malaria, bilharzia, and other water bornediseases were reported to as often occurring during and immediatelyafter floods, (UgandanNAPA 2007), According totheTanzania NAPA (2007), Malariaprevalencehasbeen reported tom occur in areaswhere it wasnot commonly found in the previousdecadefor examplein some partsof Kagera, Musoma, Mwanza in Tanzania; Kisumu and Kiisi in Kenya. In additiontotheeven the icecaps for instanceon the KilimanjaroMountainhastremendouslyreduced as a result of accelerated icemelt. It is also anticipatedtoacceleratethepopular icecap melt too. During the century, sea level rose about 15 cm (6 inches) due to melting of ice and expansionof warmer waters. Models predict that sea level may riseas much as 59 cm (23 inches) during the Century, threatening coastalcommunities, wetlands, and coralfees. Arctic sea iceis melting. The summer thicknessof sea iceis about halfof what it was is 1950. Glacier and permafrost are melting for instanceover the past 100 years, mountainglacier inall areasof the world have decreased in size and so has the amount of permafrost inthe Arctic. Water: Water ismost likely to becomescarcedue to the increased ratesof evaporationaswell as the variationintherainfall patterninsome areas. The anticipated climatevariabilityinform of long droughtswill worsen the availabilityofand accessibilitytocleanwater particularlythepoor or those who depend on rivers, streams, boreholes. Thisis becausesuch sourcemay be dried out or lowering of water levels, in springs, rivers, underground aquifers. Communitieswillveer to any availablewater irrespectiveofits qualityhence pausing a danger for water borne diseases, hardenthe productionof hydroelectric power, limit water transport. For instancethe declining water levels of lake Victoriain2002 to2004 left many boat landing sites and harbourshigh and dry thusaffecting water transport
  • 70.
    negatively; the extensionofthe Owen falls dam (Kiira and Nalubaale) opened in 2000 appearstohave been designed to operatewith conditions of high averagewater levels seen between1960 1990 basing on the inability of thepower plant to operateat full capacityduring thelow water levels of 2002. In Tanzania, thepower cut off wasextremealso as the mega like Kidatu could not operateat full capacity. Thiswasportrayed through a more than12 hours cut off. Tourism: It predominatelydependson thebeautifulglamorousnatural featureslike mountains, habitatsand associated flora and fauna. Climate changewill distort the naturalenvironment toas well affect the tourism sector negatively. To makemattersworse, floods may destroythe roads to accessthe distant tourist sites. Thisis becausemost of the tourists attractionsitesarelocated in theremote areasof which their roads are impassableduring therainyseason. Sincethe rainfallpatternisunreliable and unpredictable, thiswillimpedethe movement of the touriststosuch sites. The scenariowill ultimatelyslump the economieswhich depend on tourism. Climatechangewill affect all thedifferent sectors of a countryand ultimatelythemicroeconomicalstatusof thegreatlyaffected areasor countriesmoreso the developing countries. Thisis becausethey may not be robust enough to copeup with the changeshence rendering them variabilityand change. Strategies to address Climate change. It is responsibilityfor all people at a household or communitylevel, NGO’s, government, regionalgroupings, and the internationalcommunityat large to striveto reverse the situation. Thisisbecauseeveryone contributestothe existenceof the problem though the magnitudeof contributiondiffers. To makemattersworse, theeffects cut across i.e affectsall. However it may be difficult toreverse thesituationbut theefforts should revolve around strategiestoadapt tothe climatechangesaswell as reducing theemission of GHG. Some of the avenues to fight climatechangemayinclude, Renewable energy sources: Countriesshould adopt the use of renewableenergy resourcessuch as solar, nuclear, biogas, geothermal, etc which are environmentallybenign.
  • 71.
    In thiscase theyshould advocateagainst theuseof fossil fuel such as coal, petroleum and naturalgaswhich emit theGHG. Afforestation: people should indulgein the policieswhich encouragethe plantationoftrees such as agro-forestry. Thisis becausetheyact as carbon sink to minimizetheamount of the carbondioxideinthe atmosphere. Ambient standards: The Internationalcommunityshould agreeon the maximumamount ofGHG to be emitted bya source point like an industry. In the extremecaseswhere theGHG can’t be curtailed, thestrategymaybe inevitable. Use of ethanol or gasohol: The vehicles and other automobilesmayreplace petroleum with the use of ethanol and gasohol Biomassfrom sugar cane canbe used for the productionofethanol which replacethe usageof fossil fuel (petroleum inclusive) thiswill minimizetheGHG which could be emitted thecombustion. Abatement policies: Countriesshould be stringent onthose who emit more thanthe ambient standards. Abatement policiesmyinvolve thepay or cost to cater for the damagecaused bythe extra emissionsthecost as disincentivestopollution. Comply to the relevant Conventions: signatoriesshould implement accordingly. For instancethe 1985 Vienna Convention on the protectionof the ozone layer Depletion. The convention requirespartiestotakeconcern to the assessment of the cause, effects of ozone layer depletion as well as transmissionofinformationand exchangeof informationand Technology to reduceozone layer depletion. Note; the convention wasamended in Montreal1987 to becomethe protocolon substancethat depletetheozone layer. It was later revised in 1990 in London and Stockholm in1991. It representsa much more significant agreement thantheconvention. It sets a firm target for reducing and eventually eliminationofconsumption and productionofa rangeof ozone depleting substances. It recognizesthe equityof treatment of all Nationsthat produceozone depleting substance including thedeveloping countrieswhich produceless.
  • 72.
    The protocolalso dealswith the problem of non- partiesby banning trade in ozone depleting with those statesto controlthe use.  Produceless ozone depleting substances. Thisisattained through technologicaltransfer.  Restrict theimportationofozone depletion substancesthrough identifying and monitoring mechanism. For instanceRevenue authoritieslikeTRA, URA jointlywork with the Environment authoritieslikeNEMA, NEMCin Uganda and Tanzania respectively. In thiscase, the environmentalauthoritiesspecifytheozone depleting substanceswhilethe revenue authoritiesescalatethetaxestonarrow down the importation.  Research and educationofthe stake-holdersabout the substances. Thiswill also increaseon thenumber of technicalofficerstoease the monitoring.  Internationalcooperationthrough thesharing and transfer of information.  Establishment ofincentiveslike subsidyto encouragetheuse of substitutesand disincentivestoprohibit theof ozone depleting substancethrough taxation. There arevery manykey players toward theadaptationtothe climate changeand chopping ofGHG emissions.