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  1. 1. kWeather is made up of different things. Click on the different types of weatherabove to find out more about them and how they can be measured. Weather Definition Weather is the day-to-day conditions of a particular place. For example: It was raining today at school. Yesterday it was sunny at home. What is Climate? Climate is often spoken about at the same time as weather, but it is something quite different. The climate is the common, average weather conditions at a particular place over a long period of time (for example, more than 30 years). We learn about different climates around the world. Deserts have a hot and dry climate while the Antarctic has a very cold and dry climate. Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, [1] [2][3] clear or cloudy. Most weather phenomena occur in thetroposphere, just below the stratosphere. Weather generally refers to day-to-day temperature and precipitation activity, whereas climate is the term [4] for the average atmospheric conditions over longer periods of time. When used without qualification, "weather" is understood to be the weather of Earth. Weather is driven by air pressure (temperature and moisture) differences between one place and another. These pressure and temperature differences can occur due to the sun angle at any particular spot, which varies by latitudefrom the tropics. The strong temperature contrast between polar and tropical air gives rise to the jet stream. Weather systems in the mid-latitudes, such asextratropical cyclones, are caused by instabilities of the jet stream flow. Because the Earths axis is tilted relative to its orbital plane, sunlight is incident at different angles at different times of the year. On Earths surface, temperatures usually range ±40 °C (−40 °F to 100 °F) annually. Over thousands of years, changes in Earths orbit affect the amount and distribution of solar energy received by the Earth and influence long- term climate and global climate change. Forecasting Forecast of surface pressures five days into the future for the north Pacific, North America, and north Atlantic ocean as on 9 June 2008 Weather forecasting is the application of science and technology to predict the state of theatmosphere for a future time and a given location. Human beings have attempted to predict the weather informally for [25][26] millennia, and formally since at least the nineteenth century. Weather forecasts are made by
  2. 2. collecting quantitative data about the current state of the atmosphere and using scientific understanding [27]of atmospheric processes to project how the atmosphere will evolve.Once an all-human endeavor based mainly upon changes in barometric pressure, current weather [28][29]conditions, and sky condition, forecast models are now used to determine future conditions. Humaninput is still required to pick the best possible forecast model to base the forecast upon, which involvespattern recognition skills, teleconnections, knowledge of model performance, and knowledge of modelbiases. The chaotic nature of the atmosphere, the massive computational power required to solve theequations that describe the atmosphere, error involved in measuring the initial conditions, and anincomplete understanding of atmospheric processes mean that forecasts become less accurate as thedifference in current time and the time for which the forecast is being made (the range of the forecast)increases. The use of ensembles and model consensus helps to narrow the error and pick the most likelyoutcomeWeatherWeather is the state of the atmosphere at a given time and place. Most weather takes place inthetroposphere, the lowest layer of the atmosphere.Weather is measured and described in a variety of ways by meteorologists, scientists who study andpredict weather. Air temperature and pressure, the amount and type of precipitation, the strength anddirection of wind, and the types of clouds are all described in a weather report.Weather changes each day because the air in our atmosphere is always moving, distributing energy fromtheSun. In most places in the world, the types of weather events also vary throughout the yearas seasons change.What is Weather? The term weather describes the state of the air at aWeather... particular place and time – whether it is warm or cold, wet or dry, and how cloudy or windy it is, for example. The normal pattern of weather experienced in a particular area over a long period of time is known as theclimate.Climate... The climate tells us how hot, cold or wet it is likely to be in different parts of the world at different times of year. For example, tropical countries have hot climates and the Antarctic has a cold climate.What is climate?Climate is the average weather usually taken over a 30-year time period
  3. 3. for a particular region and time period. Climate is not the same asweather, but rather, it is the average pattern of weather for a particularregion. Weather describes the short-term state of the atmosphere.What is our climate system? The atmosphere covers the Earth. It is a thin layer of mixedAtmosphere gases which make up the air we breathe. This thin layer also helps the Earth from becoming too hot or too cold. Oceans cover about 70 percent of Earths surface. TheirOceans large size and thermal properties allow them to store a lot of heat. Land covers 27 percent of Earths surface and landLand topography influences weather patterns. Ice is the worlds largest supply of freshwater. It covers the remaining 3 percent of Earths surface including most ofIce Antarctica and Greenland. Ice plays an important role in regulating climate, because it is highly reflective. The biosphere is the part of Earths atmosphere, land, andBiosphere oceans that supports any living plant, animal, or organism. It is the place where plants and animals, including humans, live.What is weather?The weather is just the state of the atmosphere at any time, includingthings such as temperature, precipitation, air pressure and cloud cover.Daily changes in the weather are due to winds and storms. Seasonalchanges are due to the Earth revolving around the sun.What causes weather?Because the Earth is round and not flat, the Suns rays dont fall evenly
  4. 4. on the land and oceans. The Sun shines more directly near the equatorbringing these areas more warmth. However, the polar regions are at suchan angle to the Sun that they get little or no sunlight during the winter,causing colder temperatures. These differences in temperature create arestless movement of air and water in great swirling currents todistribute heat energy from the Sun across the planet. When air in oneregion is warmer than the surrounding air, it becomes less dense andbegins to rise, drawing more air in underneath. Elsewhere, cooler denserair sinks, pushing air outward to flow along the surface and complete thecycle.Why do mountains affect weather and climate?There are two sides to a mountain: wayward and leeward. Whenever it israining, the wayward side gets the rain. As a cloud goes up the mountain,it keeps raining until there is no more water in the cloud. Now, as thecloud starts to go down the other side of the mountain, there is no moreprecipitation. So, the leeward side of the mountain doesnt get any rain.The flat ground on this side of the mountain is dry and humid.What is the Water Cycle?Earth has a limited amount of water. So, that water keeps going around.We call it the water cycle. The water cycle begins with evaporation.Evaporation is when the sun heats up water in rivers, lakes or the ocean.Then turns it into water vapor or steam. The water vapor or steam leavesthe body of water and goes into the air. Transpiration is the process bywhich plants lose water out of their leaves. Condensation is when watervapor in the air gets cold and changes back into water to form clouds.Think of it this way, when you open a cold soda on a hot summer day, yoursoda will start to sweat as water droplets form on the outside of the can.Precipitation occurs when so much water has condensed that the air cant
  5. 5. hold it anymore. This is how we get rain or snow. Collection happens whenthe precipitation falls and is collected back in the oceans, lakes andrivers. When it falls to the ground, it will soak into the earth and becomeground water. This is the water cycle and it just keeps repeating.Click Here to learn more about the Earths water cycle.Why do we have seasons?As the Earth spins on its axis, producing night and day, it also movesabout the Sun in an elliptical (elongated circle) orbit that requires 3651/4 days to complete. The Earths axis is tilted at 23.5 degrees and iswhy we have seasons. When the Earths axis points towards the Sun, it issummer for that hemisphere. When the Earths axis points away, wintercan be expected.
  6. 6. What is the significance of the Sun to the Earth?Without the Sun, there would be no weather. Earth is positioned as thethird planet, so our temperatures are sustainable for life. The averagetemperature of Mars is much colder, while Venus is much hotter.ClimateFrom Wikipedia, the free encyclopediaFor other uses, see Climate (disambiguation). Worldwide Climate Classifications
  7. 7. Climate encompasses the statistics oftemperature, humidity, atmospheric pressure,wind, precipitation,atmospheric particle count and other meteorological elemental measurements in a given region over longperiods. Climate can be contrasted to weather, which is the present condition of these elements and theirvariations over shorter periods.A regions climate is generated by the climate system, which has fivecomponents:atmosphere, hydrosphere, cryosphere, land surface, and biosphere.[1]The climate of a location is affected by itslatitude, terrain, and altitude, as well as nearbywater bodies and theircurrents. Climates can beclassified according to the average and the typical ranges of different variables, mostcommonly temperature and precipitation. The most commonly used classification scheme was originallydeveloped by Wladimir Köppen. The Thornthwaite system,[2] in use since 1948,incorporates evapotranspiration along with temperature and precipitation information and is used in studyinganimal species diversity and potential effects of climate changes. The Bergeron and Spatial SynopticClassification systems focus on the origin of air masses that define the climate of a region.Paleoclimatology is the study of ancient climates. Since direct observations of climate are not available beforethe 19th century, paleoclimates are inferred from proxy variables that include non-biotic evidence such assediments found in lake beds and ice cores, and biotic evidence such as tree rings and coral. Climatemodels are mathematical models of past, present and future climates. Climate change may occur over longand short timescales from a variety of factors; recent warming is discussed in global warming.Why do the seasons change?Answer:Seasons change because the axis of the earth is tilted by 23.5 degrees (from a line perpendicular to itsorbit). As the earth moves around its orbit there is a time when it is tilted towards the sun and soreceives a higher concentration of the suns energy (summer) and a time when it is tilted away andreceiving less energy (winter). This also explains why it is summer in N hemisphere when it is winterin S hemisphere.What are the five different world climate zones?Answer:In the Koppen system:A - Tropical Moist Climates: all months have average temperatures above 18° Celsius.B - Dry Climates: with deficient precipitation during most of the year.C - Moist Mid-latitude Climates with Mild Winters.
  8. 8. D - Moist Mid-Latitude Climates with Cold Winters.E - Polar Climates: with extremely cold winters and summers. [1]Temperature is a physical quantity that indicates degrees of hot and cold on a numerical scale. It refersto states of matter or radiation in a local region. It is measured by a thermometer, which maybe calibrated to a variety oftemperature scales.What is Temperature?In a qualitative manner, we can describe the temperature of an object as that whichdetermines the sensation of warmth or coldness felt from contact with it.It is easy to demonstrate that when two objectsof the same material are placedtogether (physicists say when they are put in thermal contact), the object with thehigher temperature cools while the cooler object becomes warmer until a point isreached after which no more change occurs, and to our senses, they feel the same.When the thermal changes have stopped, we say that the two objects (physicistsdefine them more rigorously as systems) are in thermal equilibrium . We can thendefine the temperature of the system by saying that the temperature is that quantitywhich is the same for both systems when they are in thermal equilibrium.If we experiment further with more than two systems, we find that many systems canbe brought into thermal equilibrium with each other; thermal equilibrium does notdepend on the kind of object used. Put more precisely,if two systems are separately in thermal equilibrium with a third, then they must alsobe in thermal equilibrium with each other,and they all have the same temperature regardless of the kind of systems they are.The statement in italics, called the zeroth law of thermodynamics may be restated asfollows:If three or more systems are in thermal contact with each other and all in equilibriumtogether, then any two taken separately are in equilibrium with one another. (quotefrom T. J. Quinns monograph Temperature)Now one of the three systems could be an instrument calibrated to measure thetemperature - i.e. a thermometer. When a calibrated thermometer is put in thermalcontact with a system and reaches thermal equilibrium, we then have a quantitative
  9. 9. measure of the temperature of the system. For example, a mercury-in-glass clinicalthermometer is put under the tongue of a patient and allowed to reach thermalequilibrium in the patients mouth - we then see by how much the silvery mercury hasexpanded in the stem and read the scale of the thermometer to find the patientstemperature. TemperatureA convenient operational definition of temperature is that it is a measure of theaverage translational kinetic energy associated with the disordered microscopicmotion of atoms and molecules. The flow of heat is from a high temperature regiontoward a lower temperature region. The details of the relationship to molecular motionare described in kinetic theory.The temperature defined from kinetic theory is calledthe kinetic temperature. Temperature is not directly proportional to internalenergy since temperature measures only the kinetic energy part of the internal energy,so two objects with the same temperature do not in general have the same internalenergy (see water-metal example). Temperatures are measured in one of the threestandard temperature scales (Celsius, Kelvin, and Fahrenheit).HumidityTropical forests often have high humidity.Humidity is the amount of water vapor in the air. Water vapor is the gas phase of water and isinvisible.[1] Humidity indicates the likelihood of precipitation, dew, or fog. Higher humidity reduces the
  10. 10. effectiveness of sweating in cooling the body by reducing the rate of evaporationof moisture from the skin. Thiseffect is calculated in a heat index table, used during summer weather.There are three main measurements of humidity: absolute, relative and specific. Absolute humidity is thewater content of air.[2] Relative humidity, expressed as a percent, measures the current absolutehumidity relative to the maximum for that air pressure and temperature. Specific humidity is a ratio of thewater vapor content of the mixture to the total air content on a mass basisTypes[edit]Absolute humidityAbsolute humidity is an amount of water vapor, usually discussed per unit volume. The mass of watervapor, , per unit volume of total air and water vapor mixture, , can be expressed as follows: Absolute humidity in air ranges from zero to roughly 30 grams per cubic meter when the air is saturated at 30 °C.[3] (See alsoClimate/Humidity table) The absolute humidity changes as air temperature or pressure changes. This is very inconvenient for chemical engineering calculations, e.g. for clothes dryers, where temperature can vary considerably. As a result, absolute humidity is generally defined in chemical engineering as mass of water vapor per unit mass of dry air, also known as the mass mixing ratio (see below), which is much more rigorous for heat and mass balance calculations. Mass of water per unit volume as in the equation above would then be defined asvolumetric humidity. Because of the potential confusion, British Standard BS 1339 (revised 2002) suggests avoiding the term "absolute humidity". Units should always be carefully checked. Most humidity charts are given in g/kg or kg/kg, but any mass units may be used. The field concerned with the study of physical and thermodynamic properties of gas-vapor mixtures is named Psychrometrics. Relative humidity Relative humidity is the ratio of the partial pressure of water vapor in the air-water mixture to the saturated vapor pressure of water at those conditions. The relative humidity of air is a function of both its water content and temperature. Relative humidity is normally expressed as a percentage and is calculated by using the following equation. It is defined as the ratio of the partial pressure of water vapor (H2O) in the mixture to the saturated vapor pressure of water at a prescribed temperature. [3]
  11. 11. Relative humidity is an important metric used in weather forecasts and reports, as it is anindicator of the likelihood of precipitation, dew, or fog. In hot summer weather, a rise inrelative humidity increases the apparent temperature to humans (and other animals) byhindering the evaporation of perspiration from the skin. For example, according to the HeatIndex, a relative humidity of 75% at 80°F (27°C) would feel like 83.574°F ±1.3 °F (28.652°C [4][5]±0.7 °C) at ~44% relative humidity.[edit]Specific humiditySpecific humidity is the ratio of water vapor to dry air in a particular mass, and is sometimesreferred to as humidity ratio. Specific humidity ratio is expressed as a ratio of mass of water [6]vapor, , per unit mass of dry air . This is in conflict with the ASHRAE 2009Handbook, Ch1,1.2, (9a) which defines Specific humidity as "the ratio of the mass of watervapor to total mass of the moist air sample".That ratio is defined as: Specific humidity can be expressed in other ways including: or: Using the definition of specific humidity, the relative humidity can be expressed as However, specific humidity is also defined as the ratio of water vapor to the [7] total mass of the system in meteorology. "Mixing ratio" is used to name [8] the definition in this section beginning. [edit]Measurement hygrometer There are various devices used to measure and regulate humidity. A device used to measure humidity is called a psychrometer or hygrometer. A humidistat is a humidity-triggered switch, often used to control a dehumidifier.
  12. 12. Humidity is also measured on a global scale using remotely placed satellites. These satellites are able to detect the concentration of water in the troposphere at altitudes between 4 and 12 kilometers. Satellites that can measure water vapor have sensors that are sensitive to infrared radiation. Water vapor specifically absorbs and re-radiates radiation in this spectral band. Satellite water vapor imagery plays an important role in monitoring climate conditions (like the formation of thunderstorms) and in the development of futureweather forecasts.Atmospheric pressureFrom Wikipedia, the free encyclopedia"Air pressure" redirects here. For the pressure of air in other systems, see pressure.Atmospheric pressure is the force per unit area exerted on a surface by the weight of air above that surfacein the atmosphere of Earth (or that of another planet). In most circumstances atmospheric pressure is closelyapproximated by the hydrostatic pressurecaused by the mass of air above the measurement point. Low-pressure areas have less atmospheric mass above their location, whereas high-pressure areas have moreatmospheric mass above their location. Likewise, as elevation increases, there is less overlying atmosphericmass, so that atmospheric pressure decreases with increasing elevation. On average, a column of air onesquare centimeter in cross-section, measured from sea level to the top of the atmosphere, has a mass of about1.03 kg and weight of about 10.1 N (2.28 lbf) (A column one square inch in cross-section would have a weightof about 14.7 lbs, or about 65.4 N). Over the area of your body, there is about 1,000 kg of air; this isapproximately the same as having a small car press down on youWhat Is Atmospheric PressureJust answering the question ‘what is atmospheric pressure?’ is not enough to give a full understanding of its importance. By definitionatmospheric pressure is ‘force per unit area exerted against a surface by the weight of air above that surface’. Atmospheric pressure isclosely related to the hydrostatic pressure caused by the weight of air above the measurement point. The term standard atmosphere is usedto express the pressure in a system(hydraulics and pneumatics) and is equal to 101.325 kPa. Other equivalent units are 760 mmHg and1013.25 millibars.Mean sea level pressure (MSLP) is the pressure at sea level. This is the pressure normally given in weather reports. When home barometersare set to match local weather reports, they will measure pressure reduced to sea level, not your local atmospheric pressure. The reductionto sea level means that the normal range of fluctuations in pressure are the same for everyone.Atmospheric pressure is important in altimeter settings for flight. A altimeter can be set for QNH or QFE. Both are a method of reducingatmospheric pressure to sea level, but they differ slightly. QNH will get the altimeter to show elevation at the airfield and altitude above the airfield. QFE will set the altimeter to read zero for reference when at a particular airfield. QNH is transmitted around the world in millibars,except in the United States and Canada . These two countries use inches (or hundredths of an inch) of mercury.Atmospheric pressure is often measured with a mercury barometer; however, since mercury is not a substance that humans commonly comein contact with, water often provides a more intuitive way to visualize the pressure of one atmosphere. One atmosphere is the amount ofpressure that can lift water approximately 10.3m. A diver who is 10.3m underwater experiences a pressure of about 2 atmospheres (1of airplus 1of water). Low pressures like natural gas lines can be expressed in inches of water(w.c). A typical home gas appliance is rated for amaximum of 14 w.c.(about 0.034 atmosphere).You can see that understanding ‘what is atmospheric pressure’ is just the tip of the iceberg. Once you have the definition in mind, it reallycomes together when you see the wide variety of applications.
  13. 13. Differences between air and wind?Air is the mixture of gases that forms the atmosphere, which we have all around us. When this airbegin to move fast enough to matter, we call it wind.Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outerspace, solar wind is the movement of gases or charged particles from the sunthrough space,while planetary wind is the outgassing of light chemical elements from a planets atmosphere into space.Winds are commonly classified by their spatial scale, theirspeed, the types of forces that cause them, theregions in which they occur, and their effect. The strongest observed winds on a planet in our solarsystem occur on Neptune and Saturn.What is Air Pressure?Imagine a group of acrobats at the circus. One climbs up and stands on anothersshoulders. The weight of the acrobat on top puts more pressure on the one below.Then another acrobat climbs up and stands on the second acrobats shoulders. Nowtheres even more pressure on the acrobat on the bottom because he is under theweight of the two acrobats above him. Its the same with air. Yes, air has weight, andprobably more than you think. In fact, the weight of the air on your desk at schoolweighs about 11,000 pounds. Thats about the same weight as a school bus! Since airpressure pushes in all directions, the air pressure pushing up from under your deskbalances out the air pushing down on it, so the desk doesnt collapse under the weight.Just like an acrobat with two people stacked on his shoulders would want to move towhere there wasnt so much pressure on him, air moves from areas where the pressureis higher to where it is lowerThe density of air,The density of air, ρ (Greek: rho) (air density), is the mass per unit volume of Earths atmosphere, and isa useful value in aeronauticsand other sciences. Air density decreases with increasing altitude, asdoes air pressure. It also changes with variances in temperature or humidity. At sea level and at 15 °Caccording to ISA (International Standard Atmosphere), air has a density of approximately 1.225 3 3kg/m (0.0023769 slugs/ft ).Rain
  14. 14. Torrential rain in Greece.Rain is liquid water in the form of droplets that have condensed fromatmospheric water vapor andthen precipitated—that is, become heavy enough to fall under gravity. Rain is a major component of the watercycleand is responsible for depositing most of the fresh water on the Earth. It provides suitable conditions formany types of ecosystem, as well as water for hydroelectric power plants and crop irrigation.The major cause of rain production is moisture moving along three-dimensional zones of temperature andmoisture contrasts known as weather fronts. If enough moisture and upward motion is present, precipitationfalls from convective clouds (those with strong upward vertical motion) such ascumulonimbus (thunder clouds)which can organize into narrow rainbands. In mountainous areas, heavy precipitation is possible where upslopeflow is maximized within windward sides of the terrain at elevation which forces moist air to condense and fallout as rainfall along the sides of mountains. On the leeward side of mountains, desert climates can exist due tothe dry air caused by downslope flow which causes heating and drying of the air mass. The movement ofthe monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes.rain·fall1. A shower or fall of rain.2. The quantity of water, expressed in inches, precipitated as rain, snow, hail, or sleet in a specified areaand time interval.RainfallRainfall in IrelandMost of the eastern half of the country gets between 750 and 1000 (mm) of rainfall in the year. Rainfall in the westgenerally averages between 1000 and 1400 mm. In many mountainous districts rainfall exceeds 2000mm per year.The wettest months, in almost all areas are December and January. April is the driest month generally across thecountry. However, in many southern parts, June is the driest. Hail and snow contribute relatively little to theprecipitation measured.How Often Does it Rain?The general impression is that it rains quite a lot of the time in Ireland, but two out of three hourly observations will notreport any measurable rainfall. The average number of wet days (days 1mm or more of rain) ranges from about 150days a year along the east and south east coasts, to about 225 days a year in parts of the west.How Heavy is the Rain?
  15. 15. Unlike the rain in many other countries, especially in the tropics, average hourly rainfall amounts in Ireland are quitelow, ranging from 1 to 2mm. Short-term rates can of course be much higher: for example, an hourly total of 10mm isnot uncommon and totals of 15 to 20mm in an hour may be expected to occur once in 5 years. Hourly totalsexceeding 25mm are rare in this country and when they do occur they are usually associated with heavythunderstorms.Information on the frequency of heavy rainfalls is often required by engineers, architects and others, usually inconnection with design criteria for water management or drainage schemes. A depth duration frequency model allowsfor the estimation of point rainfall frequencies for a range of durations for any location in Ireland. For moreinformation, .An atmosphere (New Latin atmosphaera, created in the 17th century from Greek ἀτμός [atmos] [1] [2]"vapor" and συαῖρα [sphaira] "sphere" ) is a layer of gases that may surround a material body of [3]sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained fora longer duration, if the gravity is high and the atmospheres temperature is low. Some planets consistmainly of various gases, but only their outer layer is their atmosphere.The term stellar atmosphere describes the outer region of a star, and typically includes the portionstarting from the opaque photosphere outwards. Relatively low-temperature stars may form compoundmolecules in their outer atmosphere. Earths atmosphere, which containsoxygen used bymost organisms for respiration and carbon dioxide usedby plants, algaeand cyanobacteria for photosynthesis, also protects living organisms from geneticdamage by solar ultraviolet radiation. Its current composition is the product of billions of years ofbiochemical modification of the paleoatmosphere by living organisms.The present atmosphere of the Earth is probably not its original atmosphere.Our current atmosphere is what chemists would call an oxidizing atmosphere,while the original atmosphere was what chemists would call a reducingatmosphere. In particular, it probably did not contain oxygen.Composition of the AtmosphereThe original atmosphere may have been similar to the composition of the solarnebula and close to the present composition of the Gas Giant planets, though thisdepends on the details of how the planets condensed from the solar nebula. Thatatmosphere was lost to space, and replaced by compounds outgassed from thecrust or (in some more recent theories) much of the atmosphere may have comeinstead from the impacts of cometsand other planetesimals rich in volatilematerials.The oxygen so characteristic of our atmosphere was almost all produced byplants (cyanobacteria or, more colloquially, blue-green algae). Thus, the present
  16. 16. composition of the atmosphere is 79% nitrogen, 20% oxygen, and 1% othergases.Layers of the AtmosphereThe atmosphere of the Earth may be divided into several distinct layers, as thefollowing figure indicates. Layers of the Earths atmosphereEarths AtmosphereThe atmosphere is a mixture of nitrogen (78%), oxygen (21%), and other gases (1%) that surroundsEarth. High above the planet, the atmosphere becomes thinner until it gradually reaches space. It isdivided into five layers. Most of the weather and clouds are found in the first layer.The atmosphere is an important part of what makes Earth livable. It blocks some of the Suns dangerousrays from reaching Earth. It traps heat, making Earth a comfortable temperature. And the oxygen withinour atmosphere is essential for life.cryosphere [1]The cryosphere (from the Greek κρύος cryos "cold", "frost" or "ice" andσυαῖρα sphaira, "globe, ball" ) isthe term which collectively describes the portions of the Earth’s surface where water is in solid form,including sea ice, lake ice, river ice, snow cover, glaciers, ice caps and ice sheets, and frozen ground(which includes permafrost). Thus there is a wide overlap with thehydrosphere. The cryosphere is anintegral part of the global climate system with important linkages and feedbacks generated through its
  17. 17. influence on surface energy and moisture fluxes, clouds, precipitation, hydrology, atmospheric andoceanic circulation. Through these feedback processes, the cryosphere plays a significant role in globalclimate and in climate modelresponse to global change.biosphereThe biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, a [1]closed (apart from solar and cosmic radiation), and self-regulating system. From thebroadestbiophysiological point of view, the biosphere is the global ecologicalsystem integrating all livingbeings and their relationships, including their interaction with the elements ofthe lithosphere, hydrosphere, and atmosphere. The biosphere is postulated to have evolved, beginning [2]through a process of biogenesis or biopoesis, at least some 3.5 billion years ago.In a broader sense; biospheres are any closed, self-regulating systems containing ecosystems; includingartificial ones such asBiosphere 2 and BIOS-3; and, potentially, ones on other planets or moons. but they [3]can be open systems too.lithosphereThe lithosphere (Ancient Greek: λίθος [lithos] for "rocky", andσυαῖρα [sphaira] for "sphere") is the [1]rigid outermost shell of a rockyplanet. On Earth, it comprises the crust and the portion of theuppermantle that behaves elastically on time scales of thousands of years or greater.In the Earth, the lithosphere includes the crust and the uppermost mantle, which constitute the hard andrigid outer layer of the Earth. The lithosphere is underlain by the asthenosphere, the weaker, hotter, anddeeper part of the upper mantle. The boundary between the lithosphere and the underlyingasthenosphere is defined by a difference in response to stress: the lithosphere remains rigid for very longperiods of geologic time in which it deforms elastically and through brittle failure, while the asthenospheredeforms viscously and accommodates strain through plastic deformation. The lithosphere is brokeninto tectonic plates. The uppermost part of the lithosphere that chemically reacts tothe atmosphere, hydrosphere and biospherethrough the soil forming process is called the pedosphere.The concept of the lithosphere as Earth’s strong outer layer was developed by Joseph Barrell, who wrote [2][3][4][5]a series of papers introducing the concept. The concept was based on the presence of significantgravity anomalies over continental crust, from which he inferred that there must exist a strong upper layer(which he called the lithosphere) above a weaker layer which could flow (which he called theasthenosphere). These ideas were expanded by Harvard geologist Reginald Aldworth Daly in 1940 with [6]his seminal work "Strength and Structure of the Earth" and have been broadly accepted by geologistsand geophysicists. Although these ideas about lithosphere and asthenosphere were developed longbefore plate tectonic theory was articulated in the 1960s, the concepts that a strong lithosphere exists andthat this rests on a weak asthenosphere are essential to that theory.There are two types of lithosphere: Oceanic lithosphere, which is associated with Oceanic crust and exists in the ocean basins
  18. 18. Continental lithosphere, which is associated with Continental crustThe hydrosphere (from Greek ὕδωρ - hudōr, "water" and συαῖρα - sphaira, "sphere" ) in physical [1] [2]geography describes the combined mass of water found on, under, and over the surface of a planet. 18The total mass of the Earths hydrosphere is about 1.4 × 10 tonnes, which is about 0.023% of the 12Earths total mass. About 20 × 10 tonnes of this is in the Earths atmosphere (the volume of one tonne ofwater is approximately 1 cubic metre). Approximately 75% of the Earths surface, an area of some 361million square kilometers (139.5 million square miles), is covered by ocean. The averagesalinity of the [3]Earths oceans is about 35 grams of salt per kilogram of sea water (3.5%)The hydrosphere is the liquid water component of the Earth. It includes theoceans, seas, lakes, ponds, rivers and streams. The hydrosphere coversabout 70% of the surface of the Earth and is the home for many plants andanimals. (U.S. Fish and Wildlife Service/Craig Blacklock)The hydrosphere, like the atmosphere, is always in motion. The motion ofrivers and streams can be easily seen, while the motion of the water withinlakes and ponds is less obvious. Some of the motion of the oceans and seascan be easily seen while the large scale motions that move water greatdistances such as between the tropics and poles or between continents aremore difficult to see. These types of motions are in the form of currents that
  19. 19. move the warm waters in the tropics toward the poles, and colder water fromthe polar regions toward the tropics. These currents exist on the surface of theocean and at great depths in the ocean (up to about 4km). The characteristics of the ocean which affects its motion are its temperature and salinity. Warm water is less dense or lighter and therefore tends to move up toward the surface, while colder water is more dense or heavier and therefore tends to sink toward the bottom. Salty water is also more dense or heavier and thus tends to sink, while fresh or less salty water is less dense or lighter and thus tends to rise toward the surface. The combination of the(NOAA Photo Collection/Commander waters temperature and salinity determines whether itJohn Bortniak, NOAA Corps) rises to the surface, sinks to the bottom or stays at someLarge version intermediate depth.ES0108 Hydrosphere/Atmosphere InteractionsLayers of the Atmosphere:The earth is surrounded by the atmosphere, which is the body of air or gasses that protects the planetand enables life. Most of our atmosphere is located close to the earths surface where it is most dense.The air of our planet is 79% nitrogen and just under 21% oxygen; the small amount remaining iscomposed of carbon dioxide and other gasses. There are five distinct layers of the earth. Lets look ateach, from closest to farthest from the earth...Troposphere:The layer of the atmosphere closest to the earth is the troposphere. This layer is where weatheroccurs. It begins at the surface of the earth and extends out to about 4-12 miles. The temperature ofthe troposphere decreases with height. This layer is known as the lower atmosphere.
  20. 20. Stratosphere:Above the troposphere is the stratosphere, which extends to about 30-35 miles above the earthssurface. Temperature rises within the stratosphere but still remains well below freezing.Mesosphere:From about 35 to 50 miles above the surface of the earth lies the mesosphere, where the air isespecially thin and molecules are great distances apart. Temperatures in the mesosphere reach a lowof -184°F (-120°C). The stratosphere and the mesosphere are the middle atmosphere.Thermosphere:The thermosphere rises several hundred miles above the earths surface, from 50 miles up to about400 miles. Temperature increases with height and can rise to as high as 3,600°F (2000°C).Nonetheless, the air would feel cold because the hot molecules are so far apart. This layer is known asthe upper atmosphere.Exosphere:Extending from the top of the thermosphere to 6200 miles (10,000 km) above the earth is theexosphere. This layer has very few atmospheric molecules, which can escape into space.Pauses...:Between each layer of the atmosphere is aboundary. Above the troposphere is thetropopause; above the stratosphere is thestratopause; above the mesosphere is themesopause; and above the thermosphere is thethermopause. At these "pauses," maximum changebetween the "spheres" occur.The Layered AtmosphereStand outside and look up. What doyou see? You might see blue sky orwooly clouds. At night you might seestars, a satellite or a crescent moon.What you are not seeing, however, isthe complexity of our atmosphere. Theatmosphere is a protective layer of
  21. 21. gasses that shelters all life on Earth, keeping temperatures within a relativelysmall range and blocking out harmful rays of sunlight.The atmosphere has five different layers that are determined by the changesin temperature that happen with increasing altitude.TroposphereLiving at the surface of the Earth, we are usually only aware of the eventshappening in the lowest layer, the troposphere, where all weather occurs. Thebase of this layer is warmer than its top because the air is heated by thesurface of the Earth, which absorbs the Sun’s energy.StratosphereAbove the troposphere lies the stratosphere where jet airplanes fly.Temperatures increase with altitude because of increasing amounts of ozone.The ozone layer within the stratosphere absorbs harmful ultraviolet rays ofsunlight.MesosphereAs the mesosphere extends upward above the stratosphere, temperaturesdecrease. The coldest parts of our atmosphere are located in this layer andcan reach –90°C.ThermosphereIn the forth layer from Earth’s surface, the thermosphere, the air is thin,meaning that there are far fewer air molecules. The thermosphere is verysensitive to solar activity and can heat up to 1,500°C or higher when the Sunis active making an aurora that lights up the night sky. Astronauts orbitingEarth in the space station or space shuttle spend their time in this layer.ExosphereThe upper layer of our atmosphere, where atoms and molecules escape intospace, is called the exosphere.Atmospheric pressure is the force per unit area exerted on a surface by the weight of air above thatsurface in the atmosphere of Earth (or that of another planet). In most circumstances atmosphericpressure is closely approximated by the hydrostatic pressurecaused by the mass of air above themeasurement point. Low-pressure areas have less atmospheric mass above their location, whereas high-pressure areas have more atmospheric mass above their location. Likewise, as elevation increases, thereis less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation.On average, a column of air one square centimeter in cross-section, measured from sea level to the topof the atmosphere, has a mass of about 1.03 kg and weight of about 10.1 N (2.28 lbf) (A column onesquare inch in cross-section would have a weight of about 14.7 lbs, or about 65.4 N). Over the area of
  22. 22. your body, there is about 1,000 kg of air; this is approximately the same as having a small car press down [1]on you. PressurePressure is defined as force per unit area. It is usually more convenient to use pressurerather than force to describe the influences upon fluid behavior. The standard unit forpressure is the Pascal, which is a Newton per square meter.For an object sitting on a surface, the force pressing on the surface is the weight of theobject, but in different orientations it might have a different area in contact with thesurface and therefore exert a different pressure.Wind speed, or wind velocity, is a fundamental atmospheric rate.Wind speed affects weather forecasting, aircraft and maritime operations, construction projects, growth [1]and metabolism rate of many plant species, and countless other implications.Wind speed is now commonly measured with an anemometer but can also be classified using theolder Beaufort scale which is based on peoples observation of specifically defined wind effects.Climate variation factorsThe climate of any region is largely determined by four geographic aspects:Latitude, distance from the sea, direction of the prevailing winds and elevation.
  23. 23. Climate variation factorsOther factors influence the global climate system: atmosphere, oceans, ice, land and the various forms oflife.Ultraviolet, visible and infra-red solar radiations are Earths main sources of energy. There is anestablished balance between the incmoing solar energy and the telluric infra-red radiation emitted by theEarth. Part of the Earths radiation is absorbed and reemitted by the greenhouse effect and part is lost inspace. Youd be hard pressed to find people anywhere that dont have an opinion on the greenhouseeffect or solar radiations one way or the other.Horizontal variation of solar energyThe balance is fragile and any variation in the factors that affect this incoming and outgoing energyprocess or which modifies the energy repartition will affect the world climate.Natural factorsThe climate changed during Earths history. Ice ages alternating with warm periods provide an
  24. 24. example. Some changes were worlwide, while others simply affected an area or a hemisphere. Inaddition, a number of natural factors contribute to modify the Earths climate during various periods. It isimportant to understand these factors when seeking to detect the influence of humanity on the climate: Variations of the solar energy emissions. The quantity of energy emitted by the Sun is not constant.There are evidences revealing that the Earths temperature corresponds to a solar cycle. Long termchanges can occur. Modifications of the Earths orbit. The orbit of the Earth around the Sun changes slowly. Thisinfluences the quantity of energy which is reflected and absorbed. It is thought that these variations ofEarths orbit are one of the factors that triggered the ice ages.Seasonal variations of the air temperature The greenhouse effect. Approximately 1/3 of the energy emitted by the Sun returns to space afterpenetrating Earths atmosphere. A fraction of what remains is then absorbed by the atmosphere, but themajor part is absorbed by the Earths surface. The surface returns infra-red energy and while part of thisenergy is lost in space, another part is absorbed again and re-emitted by the clouds and gases like watervapor, carbon dioxide, methane and oxide nitrous. This contributes to heat Earths surface and thetroposphere to a temperature 33°C higher than what it would be otherwise.It is the natural greenhouseeffect which is essential for life. Aerosols. These are very fine particles that remain in suspension in the atmosphere during a very longtime. They reflect the solar radiation and also absorb it. By modifying the quantity of the aerosols in theatmosphere, one modifies the quantity of the reflected and absorbed solar energy.Human factors The greenhouse effect amplification. The greenhouse gases naturally present in the atmosphere(e.g., water vapor, carbon dioxide, methane and oxide nitrous) keep the Earth at a sufficiently hightemperature so that life is possible. Scientific studies reveal that various human activities, whosecombustion of fossile fuels for producing electrical energy, heating and transport, produce greenhousegases. By increasing concentrations of these gases and by rejecting new greehouse gases such aschloroflurocarbures (CFC), humans are likely to be contributing to increasing the average temperatures ofEarth. Lan use evolution. By replacing forests with arable lands or the natural vegetation by asphalt andconcrete, humanity modifies the way in which terrestrial surface reflects sunlight and releases heat. Allthese changes can also modify the regional configurations of evaporation, streaming and rains.
  25. 25. Atmospheric aerosols. Due to its agricultural and industrial activities, humanity adds great quantitiesof fine particles called aerosols to the atmosphere. Most of the aerosols are quickly falling due to gravityand precipitations, but they do not less influence the atmosphere radiative absorption. It is the quantityand the nature of these particles as well as the nature of underneeth surface (land or water) thatdetermine if this have a heating effect of not. Nevertheless, the regional effects can be important.Types of Climate VariationClimate, although very slowly, keeps evolving. There are many causes behind variation in climate.Climate variations can be categorized into two broad contexts. Natural Climate Variation: There are several natural causes that force climate to change across time and scale. It can be further drilled down into the following categories.o Natural Forcings of the Climate SystemNatural Forcings of the Climate SystemNatural forcings are of two types.External Forcings: These are essentially linked to changesin the orbital parameters of the earth that control theintensity and location of incident solar radiation, andfluctuations in solar energy.Internal Forcings: These comprise all those changes thatoccur within the earth system itself, in particular volcanicactivity, fluctuations in ocean circulations and large-scalechanges in the marine and terrestrial biosphere or in thecryosphere.
  26. 26. The Sun and the Global Energy BalanceThe Sun is the prime source of external energy for the earth. Every moment, huge amount of energy reaches theearth from the Sun. Let us see this animation that shows what happens to the solar radiation that reaches the earth.Of the energy that remains in the earth (absorbed by atmosphere, clouds, and earth’s surface) 64% is radiated out into the space (atmosphere and clouds) 6% is radiated directly into the space by earth’s surface 7% is utilized in the movement of air From the animation, we find that of the total energy that reaches the earth 6% is reflected by atmosphere 16% is absorbed by atmosphere 20% is reflected by clouds 3% is absorbed by clouds 51% is absorbed by oceans and land 4% is reflected by the surface of the earth 23% is utilized in evaporation of water from earth’s surfaceThis is how the balance of energy is maintained in the environment. The global energy balance is, therefore, thebalance between incoming energy from the Sun and outgoing heat from the earth.
  27. 27. Greenhouse EffectGreenhouse effect is a phenomenon whereby earth’s atmosphere traps solar radiation, caused by the presenceof gases such as carbon dioxide, water vapour, and methane that allow incoming sunlight to pass through but absorbthe heat radiated back from earth’s surface. The gases that trap heat radiated from the earth are calledgreenhouse gases (GHGs).Let us see what exactly this mechanism is.Except for GHGs, other gases have no extra capacity to absorb heat. Hence, GHGs are the main contributors intrapping heat in the atmosphere.GHG and non-GHG components in air: Greenhouse effect is essential for our survival – without greenhouse effect, the earth would become too cold to live. The increasing greenhouse effect is the prime concern for our survival – being too hot is not pleasing eitherGreenhouse Gases Non-Greenhouse GasesWater vapour, H2O Nitrogen, N2Carbon dioxide, CO2 Oxygen, O2Methane, CH4 Argon, ArNitric oxide, NO2 Carbon monoxide, COOzone, O3 Sulphur dioxide, SO2HydrocarbonsChlorofluorocarbonsInternal and external forcings, global energy balance, radiative forcing and greenhouse effect together constitute thenatural forcings of the climate. These are the natural causes that forces climate to change.Now let us study about the natural climate variability.
  28. 28. o Natural Variability of the ClimateNatural Variability of the ClimateNatural climate variability, as the name suggests, is caused by natural factors.There are lots of natural factors that cause significant changes in the climate. These causes canbe within the earth or coming from outside the earth. Based on this, the natural climatevariability can be categorized into two groups.Externally Induced Climate Variability: It refersto the impact of some external factor that leads tovariability, such as the impact of Variations in solar radiation Solar and lunar tidesInternally Induced Climate Variability: It refers tointernal interactions between components of theclimate system, such as the interaction between Ocean and atmosphere Atmosphere and biosphere  Externally and Internally Induced Climate Variability  Feedback Feedback Feedback is the response of the climate to the internal variability of the climate system and to external forcings Interestingly, the response of climate against a change can induce or reduce further change. Based on this, feed can be classified into Positive Feedback: A positive feedback cycle is a cycle where the effect reinforces the cause. This means that impact will go on increasing. Let us understand the example shown in the screen. When the surface temperature increases, it leads to increased evaporation from the ocean. This adds more wate vapour to the atmosphere. Water vapour, being a GHG, further increases the surface temperature. Thus, we find that an increase in surface temperature assists a further increase in the surface temperature. This instance of positive feedback.
  29. 29. Negative Feedback: A negative feedback cycle is a cycle where the effect resists the cause. This means that th impact will go on diminishing. Let us understand the example shown in the screen. When surface temperature increases, it leads to a higher evaporation rate. More water vapour in the atmosphere means more cloud formation. More clouds lead to increased albedo of the earth. This decreases the surface temperature slightly. This leads to decreased evaporation from oceans. This leads to lesser clouds and lowering earth’s albedo. This leads to decrease in surface temperature. Thus, we find that an increase in surface temperature resists further increase in surface temperature. This is an instance of negative feedback.  Global and Hemispherical VariabilityGlobal and Hemispherical VariabilityClimate varies naturally on all time-scales. In the last few million years, the glacial periods andthe inter-glacial periods have alternated as a result of variations in earth’s orbit.
  30. 30. However, recently it was discovered that in the last glacial period large and very rapidtemperature variations took place over large parts of the globe, in particular in the higherlatitudes of the Northern Hemisphere. These led to an increase in temperature over theseregions by a few degrees. In contrast, the last 10,000 years appear to have been relatively morestable, though locally quite large changes have occurred.Recent analyses suggest that in the Northern Hemisphere climate of the past 1,000 years wascharacterized by an irregular but steady cooling, followed by a strong warming during the 20thcentury.For the Southern Hemisphere, the data is not as precise, but it does indicate that temperaturechanges in past centuries were markedly different from those in the Northern Hemisphere; theonly obvious similarity being the strong warming during the 20th century.Over and above the global variability, climate can change at a regional level too. Let us find outmore about this. o  Regional VariabilityRegional VariabilityRegional or local climate is generally much more variable than climate on a hemispheric orglobal scale because regional or local variations in one region are compensated for by oppositevariations elsewhere.A good example for this kind of variability is the ENSO (El Niño Southern Oscillation).ENSO (El Niño Southern Oscillation)Source: NASAIt is a coupled phenomenon of ocean-atmosphere interaction. El Niño occurs in the Pacific
  31. 31. Ocean when there is a shift in ocean temperatures (towards warm) due to atmosphericconditions in the tropical Pacific. These oceanic changes normally begin in December aroundChristmas; hence the South Americans have named the phenomenon El Niño, meaning‘Little Boy’. It has been observed that El Niño impacts weather patterns all over theworld. It occurs at regular intervals of about four years and primarily affects the Pacific coast ofSouth America, lasting for 8â€―10 months.The Southern Oscillation is the see-saw pattern of reversing surface air pressure between theeastern and western tropical Pacific; when the surface pressure is high in the eastern tropicalPacific it is low in the western tropical Pacific, and vice-versa. Since the ocean warming andpressure reversals are, for the most part, simultaneous, scientists call this phenomenon the ElNino/Southern Oscillation or ENSO for short.Normally, the trade winds blow towards the west across the Pacific, pushing warm surfacewater away from the South American coast and this leads to upwelling of nutrients along thePeru coast. Along this coast, the cold water is rich in nutrients and supports a diversity ofmarine life and provides a good catch of fish for fishermen around this part of the year.During an El Niño period, the winds slow down. Warm water accumulates at the surface andcauses significant reduction in the quantities of nutrients, plankton, and fish. This leads tochanges in weather patterns. A wide variety of disasters that have taken place all over the worldduring these periods have been attributed to El Niño. When pressure is high in the Pacificregion, it tends to be low in the Indian Ocean, affecting the movement of the monsoon winds.Thus, we find that natural climate variation manifests itself either globally or regionally. Thesevariations are caused by both internal and external factors. Common phenomena contributing toclimate variation include natural forcings, radiative forcing, greenhouse effect, and feedbackcycles.Now, we will discuss the human-induced climate variation. Human-induced Climate Variation: Human activities also influence the climate. The major human-induced causes include changes in greenhouse gas (GHG) concentrations, changes in aerosol levels, and changes in land use and land cover.o Enhanced Greenhouse EffectEnhanced Greenhouse EffectMost human activities influence the climate by bringing about an increase in the concentration of greenhouse gasesin the atmosphere. An increase in the concentration of greenhouse gases leads to an increase in the magnitude ofthe greenhouse effect. This is known asenhanced greenhouse effect.The enhanced greenhouse effect is the direct result of human activities through processes such as the burning offossil fuels, industrial operations and forest clearing releasing carbon dioxide, methane and nitrous oxide into theatmosphere. Chlorofluorocarbons, or CFCs, are also potent greenhouse gases, and as an added danger, they alsodestroy the ozone layer.A rough approximate of the contribution of GHGs is given in the following figures.
  32. 32. Global annual emissions of anthropogenic Share of different anthropogenic GHGs in totalGHGs from 1970 to 2004 emissions in 2004 World Climate ZonesHave you ever wondered why one area of the world is a desert, another agrassland, and another a rainforest? Why are there different forests anddeserts, and why are there different types of life in each area? The answer isclimate.Climate is the characteristic condition of the atmosphere near the earthssurface at a certain place on earth. It is the long-term weather of that area (atleast 30 years). This includes the regions general pattern of weatherconditions, seasons and weather extremes like hurricanes, droughts, or rainyperiods. Two of the most important factors determining an areas climate areair temperature and precipitation.World biomes are controlled by climate. The climate of a region will determinewhat plants will grow there, and what animals will inhabit it. All threecomponents, climate, plants and animals are interwoven to create the fabric ofa biome.Some facts about climate
  33. 33. The suns rays hit the equator at a direct angle between 23 ° N and 23° S latitude. Radiation that reaches the atmosphere here is at its mostintense.In all other cases, the rays arrive at an angle to the surface and areless intense. The closer a place is to the poles, the smaller the angleand therefore the less intense the radiation.Our climate system is based on the location of these hot and cold air-mass regions and the atmospheric circulation created by trade windsand westerlies.Trade winds north of the equator blow from the northeast. South ofthe equator, they blow from the southeast. The trade winds of thetwo hemispheres meet near the equator, causing the air to rise. Asthe rising air cools, clouds and rain develop. The resulting bands ofcloudy and rainy weather near the equator create tropical conditions.Westerlies blow from the southwest on the Northern Hemisphereand from the northwest in the Southern Hemisphere. Westerliessteer storms from west to east across middle latitudes.Both westerlies and trade winds blow away from the 30 ° latitudebelt. Over large areas centered at 30 ° latitude, surface winds arelight. Air slowly descends to replace the air that blows away. Anymoisture the air contains evaporates in the intense heat. The tropicaldeserts, such as the Sahara of Africa and the Sonoran of Mexico,exist under these regions.SeasonsThe Earth rotates about its axis, which is tilted at 23.5 degrees. Thistilt and the suns radiation result in the Earths seasons. The sunemits rays that hit the earths surface at different angles. These raystransmit the highest level of energy when they strike the earth at aright angle (90 °). Temperatures in these areas tend to be the hottestplaces on earth. Other locations, where the suns rays hit at lesserangles, tend to be cooler.As the Earth rotates on its tilted axis around the sun, different partsof the Earth receive higher and lower levels of radiant energy. Thiscreates the seasons.
  34. 34. Köppen Climate Classification SystemThe Köppen Climate Classification System is the mostwidely used for classifying the worlds climates. Mostclassification systems used today are based on the oneintroduced in 1900 by the Russian-German climatologistWladimir Köppen. Köppen divided the Earths surfaceinto climatic regions that generally coincided with worldpatterns of vegetation and soils.The Köppen system recognizes five major climate typesbased on the annual and monthly averages oftemperature and precipitation. Each type is designatedby a capital letter.A - Moist Tropical Climates are known for their hightemperatures year round and for their large amount ofyear round rain.B - Dry Climates are characterized by little rain and ahuge daily temperature range. Two subgroups, S -semiarid or steppe, and W - arid or desert, are used withthe B climates.C - In Humid Middle Latitude Climates land/waterdifferences play a large part. These climates havewarm,dry summers and cool, wet winters.D - Continental Climates can be found in the interiorregions of large land masses. Total precipitation is notvery high and seasonal temperatures vary widely.E - Cold Climates describe this climate type perfectly.These climates are part of areas where permanent ice andtundra are always present. Only about four months of theyear have above freezing temperatures.Further subgroups are designated by a second, lowercase letter which distinguish specific seasonalcharacteristics of temperature and precipitation.f - Moist with adequate precipitation in all months andno dry season. This letter usually accompanies the A, C,and D climates.
  35. 35. m - Rainforest climate in spite of short, dry season inmonsoon type cycle. This letter only appliesto A climates.s - There is a dry season in the summer of the respectivehemisphere (high-sun season).w - There is a dry season in the winter of the respectivehemisphere (low-sun season).To further denote variations in climate, a third letter wasadded to the code.a - Hot summers where the warmest month is over 22°C(72°F). These can be found in C and D climates.b - Warm summer with the warmest month below 22°C(72°F). These can also be found in C and D climates.c - Cool, short summers with less than four months over10°C (50°F) in the C and D climates.d - Very cold winters with the coldest month below -38°C(-36°F) in theD climate only.h - Dry-hot with a mean annual temperature over 18°C(64°F) in Bclimates only.k - Dry-cold with a mean annual temperature under 18°C(64°F) in Bclimates only.Major Climate Zones (Printing tip: Set printer to landscape.) Zone Latitudes Sunlight Temperatures Precipitatio
  36. 36. Tropics From Tropic of Direct sunlight Hot all year. Equator has Capricorn (23.5 S Hours and intensity don’t most season latitude) to Tropic of change much throughout Other parts Cancer (23.5 N the year. tropics have latitude) summers an winters. Subtropics From 23.5 N or S Intermediate between Typically hot; can Often dry; m (Part of latitude to about 35 N tropics and other regions. go from hot in deserts are southern U.S. or S latitude. daytime to cold at here. and much of night. Mexico) Temperate From about 30 N Fluctuates with the Fluctuate with the Precipitation (Most of U.S. latitude to about 65 N seasons. seasons. seasons. Var and Canada.) latitude (Arctic Circle); Hours and intensity are The farther south From 30 N latitude to greater in summer, less in and the closer to about 65 N latitude winter. the ocean, the less (Antarctic Circle) they fluctuate. * Polar From 60 degree N or S Changes dramatically. Sun The winters are Very dry; litt (Part of Canada latitude to each pole. is never direct (stays low very cold and the precipitation and Alaska) on horizon). summers cool to and ice cove Almost no light in winter; cold. round. all light in summer.* Maritime temperate zone: Water holds heat longer than land does, so temperatures inlocations near oceans don’t fluctuate as much during the year. These areas have coolersummers and warmer winters than inland regions.* Continental temperate zone: Areas in the middle of the continent, far from water, rangewidely in temperature. They often have very cold winters and hot summers.
  37. 37. Tropical savanna climate or tropical wet and dry climate is a type of climate that corresponds tothe Köppen climate classification categories "Aw" and "As."Tropical savanna climates have monthly mean temperature above 18°C in every month of the year andtypically a pronounced dry season, with the driest month having precipitation less than 60 mm and alsoless than (100 − [total annual precipitation {mm}/25]). This latter fact is in direct contrast to a tropicalmonsoon climate, whose driest month sees less than 60 mm of precipitation but has more than (100 –[total annual precipitation {mm}/25]). In essence, a tropical savanna climate tends to either see lessrainfall than a tropical monsoon climate or have more pronounced dry seasons.There are generally four types of a tropical savanna climate: One form of the tropical savanna climate features distinct wet and dry seasons of relatively equal duration. Most of the region’s annual rainfall is experienced during the wet season and very little precipitation falls during the dry season. The second type of a tropical savanna climate features a lengthy dry season and a relatively short wet season. This version features seven or more dry season months and five or less wet season months. There are variations within this version. On one extreme, the region receives just enough precipitation during the short wet season to preclude it from a semi-arid climate classification. This drier variation of the tropical savanna climate is typically found adjacent to regions with semi-arid climates. On the other extreme, the climate features a lengthy dry season followed by a short but extremely rainy wet season. However, regions with this variation of the climate do not experience enough rainfall during the wet season to qualify as a tropical monsoon climate. The third type of a tropical savanna climate features a lengthy wet season and a relatively short dry season. This version features seven or more wet season months and five or less dry season months. This version’s precipitation pattern is similar to precipitation patterns observed in some tropical monsoon climates. However, regions with this variation of the climate do not experience enough rainfall during the wet season to qualify as a tropical monsoon climate. The fourth, rarer form of the tropical savanna climate features a dry season with a noticeable amount of rainfall followed by a rainy wet season. In essence, this version mimics the precipitation patterns more commonly found in a tropical monsoon climate. However, regions with this version of the climate fall short of a tropical monsoon climate categorization because it either does not receive enough precipitation during the dry season, or it does not receive enough annual precipitation.Tropical climateFrom Wikipedia, the free encyclopedia
  38. 38. Locations of tropical climates, with subtypes. Af—Tropical rainforest climate. Am—Tropical monsoon climate. Aw—Tropical savanna climate.Beach in Naples, Florida lined with coconuttrees is an example of a tropical climate. Although it lies in the subtropics over ahundred miles north of the tropic of cancer, the warm waters of theGulf of Mexico give it a monthly mean temperature neverunder 18 °C (64 °F), classifying its climate as tropical.
  39. 39. Intertropical Convergence Zone vertical velocity at 500 hPa, July average in units of pascals per second. Ascent (negativevalues) is concentrated close to the solar equator; descent (positive values) is more diffuse.A tropical climate is a climate of the tropics. In the Köppen climate classification it is a non-arid climate inwhich all twelve months have mean temperatures above 18 °C (64 °F). Unlike the extra-tropics, where thereare strong variations in day length and temperature, with season, tropical temperature remains relativelyconstant throughout the year and seasonal variations are dominated by precipitation. Contents [hide]1 Subtypes2 Intertropical Convergence Zone3 References4 External links [1] Tropical rainforest climate (Af): All twelve months have average precipitation of at least 60 mm (2.4 in). These climates usually occur within 5–10° latitude of the equator. In some eastern-coast areas, they may extend to as much as 25° away from the equator. This climate is dominated by the Doldrums Low Pressure System all year round, and therefore has no natural seasons. [1] Tropical monsoon climate (Am): This type of climate, most common in Southand Central America, results from the monsoon winds which change direction according to the seasons. This climate has a driest month (which nearly always occurs at or soon after the "winter" solstice for that side of the equator) with rainfall less than 60 mm, but more than (100 − [total annual precipitation {mm}/25]). [1] Tropical wet and dry or savanna climate (Aw): These climates generally have a pronounced dry season, with the driest month having precipitation less than 60 mm and also less than (100 − [total annual precipitation {mm}/25]).
  40. 40. Temperate climateFrom Wikipedia, the free encyclopediaFor the usage in virology, see temperateness (virology). This article needs additional citations for verification. Please help improve this article byadding citations to reliable sources. Unsourced material may be challenged and removed.(January 2013) Part of the nature series Weather Calendar seasons Spring Summer Autumn Winter Tropical seasons Dry season Wet season Storms Thunderstorm (Thundersnow) Supercell
  41. 41. Downburst Lightning Tornado Waterspout Tropical cyclone (Hurricane) Extratropical cyclone Winter storm Blizzard Ice storm Dust storm Firestorm Cloud Precipitation Drizzle (Freezing drizzle) Rain (Freezing rain)Snow (Rain and snow mixed • Snow grains • Snow roller) Graupel Ice pellets
  42. 42. Hail Topics Meteorology Climate Weather forecasting Heat wave Air pollution Cold wave Weather portal V T ETemperate climate (shown in green in the map)
  43. 43. In geography, temperate or tepidlatitudes of the globe lie between thetropics and the polar regions. Thechanges in these regions betweensummer and winter are generally relatively moderate, rather than extremehot or cold.However, in certain areas, such asAsia and central North America, the variations between summer and wintercan be extreme because these areas are far away from the sea, causing them to have a continental climate. Inregions traditionally considered tropical, localities at high altitudes(e.g. parts of the Andes) may have atemperate climate.The north temperate zone extends from the Tropic of Cancer (at about 23.5 degrees north latitude) tothe Arctic Circle (at approximately 66.5 degrees north latitude). The south temperate zone extends fromthe Tropic of Capricorn (at approximately 23.5 degrees south latitude) to the Antarctic Circle (at approximately66.5 degrees south latitude). [1][2]In a very broad sense, temperate climate also includes a subtropical climate, variants: subtropicalsemidesert/desert, humid subtropical, oceanic subtropical and Mediterranean climate. However, a typicaltemperate climate is one of the four climate zones in the world, beside polar regions (subarctic climate, arcticclimate, tundra climate,ice cap climate) and the subtropics, tropics.The maritime climate is affected by the oceans, which help to sustain somewhat stable temperaturesthroughout the year. In temperate zones the prevailing winds are from the west, thus the western edge oftemperate continents most commonly experience this maritime climate. Such regions include Western Europe,and western North America at latitudes between 40° and 60° north (65°N in Europe).Continental, semi-arid and arid are usually situated inland, with warmer summers and colder winters. Heatloss and reception are aided by extensive land mass. In North America, the Rocky Mountains act as a climatebarrier to the maritime air blowing from the west, creating a semi-arid and continental climate to theeast.[3][4][5] In Europe, the maritime climate is able to stabilize inland temperature, because the major mountainrange – the Alps – is oriented east-west (the area east of the long Scandinavian mountain range is anexception).The vast majority of the worlds human population resides in temperate zones, especially in the northernhemisphere because of the mass of land.[6]
  44. 44. The temperate climate refers to zones in a range of latitudes between 40° and 60/70°.No as hot as the subtropical climate and milder than the polar climate, it is usuallydefined but by what it is not.A sub-type is the moderate oceanic climate oceanic : windy and without excessivetemperatures, which characterizes the Western shores of Europe. The four seasons arewell marked. In these climate zones you tend to find a wide range of architecture as welldue to the need for housing that can with stand both the cold and snow as well as thesummer heat. Common place in these dwellings is to have both air conditioningsystems and heating systems as well as ceiling fans with lights to help circulate the air.It is associated by leafy tree forests and meadows. It alternates relatively freshsummers with mild and wet winters.Another sub-type is the continental moderate climate which dominates the steppes. It iscold and dry in winter while being rather hot and rainy in the summer. There arefrequent storms and the transition of seasons are short. The hypercontinental climatehas short summers and dry and very cold winters. It extends over Siberia, Alaska andCanada which are covered with coniferous tree forests. ·Polar and highland climates temperature is key (again) • cold due to limited solar radiation • low angle of incidence of insolationMoisture is relatively scarce all the time except where oceans intercedeAnnual fluctuation is much greater than diurnal changes Earth - Sun relationships