Ears popping. As you climb there are less collisions outside ear drum. Once equilibrium is reached your ears “pop” to keep the same pressure.
Plants produce oxygen Release Nitrogen
Do the tube demo (vapor pressure) May want to do heat measurement here.
Climatology lecture 14 feb
ClimatologyBy: Fasihud Din NaumanBook Reference:Meteorology Today Chapter# 1.Encyclopedia of world climatology
Weather• Atmospheric state prevailing at a particular time (few hours- few days or even weeks) over a specified area (usually 30 Km across). Weather is expressed in terms of atmospheric pressure, temperature, relative humidity, light intensity, precipitation (rain, snow) and winds etc.• weather indicates changes in these atmospheric characteristics within a short period of time.
Climate• Atmospheric characteristics of an area recorded for a long duration (many years, e.g. standard thirty years by WMO for comparison).• Climate is aggregate or composite of the weather and involves both the extremes and variability of the weather.• Various atmospheric processes and surface features explain the weather, which over a longer period explains the climate.• Surface features include latitude, elevation, landform, orientation to the sun and distance from the sea. Other feature are also important like
Transpiration Radiation Temperature Rain volatilization Evaporation FertilisationIrrigation Uptake Uptake H2O C&NDrainage Mineralization Capillary rise Leaching Immobilisation Conceptual model of weather-crop-soil system
Wind speed, direction, and peak gustTemperature (oC) G23 Station Pressure 35 998Visibility(miles) 9 -16 3 hour pressure 10 change .09 Current MLT Weather 3 hour Dewpoint precipitation (oC) Sky Station ID Cover (MULTAN) 5
Earth’s Atmosphere• Atmosphere: The earth’s • Functions of Atmosphere: atmosphere is a thin envelop of This thin blanket constantly air. shields the surface and its• It consists of a physical mixture inhabitants from the of gases and particle matter dangerous UV (Ultraviolet)• Atmosphere is extended radiations from the sun. upward to many hundred kilometers. • It also protects materials• Around 99% of the atmosphere form outer space to enter lies within 30 km (19 miles) of earth. the earth’s surface.• Boundary of Atmosphere: There is no definite upper limit to the atmosphere. It becomes thinner and thinner and eventually merging with empty space, which surrounds the earth.• Aerosols: Tiny solid or liquid particles suspended in the atmosphere are called Aerosols.
Gas Characteristics• Expand or compress due to pressure, containers, etc• Easily mixed• Individual molecules far apart• Individual molecules have distinct mass• Most common measurements: – temperature, pressure, and volume 7
Gas characteristics• Density: The density of the air (or any substance) is determined by its mass and its volume.• Density=mass/volume.• Air molecules are in constant motion. Bounces of air molecules creates a tiny push. The force which air molecules on a unit area is called pressure or air pressure.
Atmospheric Pressure• Pressure = force / area. Measure of the weight of air above you Force = push or pull, especially on other air molecules Compressible More air (mass) above means more compression Air closer to the surface more dense, because compressed by the “weight” of the air above it Pressure decreases with height exponentially BAR: A force of 0.1 million newton (N) acting on a surface area of 1 square meter (1 m2). SI (System International) unit of pressure is Pascal (Pa). Where 1 Pa is the force of 1 N acting on a surface of 1 m2. common unit is hPa (hecto-pascal) (100 Pa) 9
Chemical (Gas) Composition• Each constituent has a – Source: Production – Sink : Destruction• N Source – Decaying of plants and animals• N Sink – Biological processes through bacterial activity 12
Review Hydrostatic Balance We tend to make the assumption that the atmosphere is in Hydrostatic Balance. Hydrostatic Balance is when the net upward force on a slab of air equals the net downward force. dP = − ρg dz 13
ReviewTemperature and Density Temp is the measure of the kinetic energy of molecules (speed) KE = ½ mv2 Warmer air is less dense Consider the ideal gas law: P=RT If we consider constant pressure, then: P/R = T Or: Constant = T We can see then, if the temperature increases, density must decrease It follows: Colder air is more dense 14
Layers of the Atmosphere Defined by changes in temperature with height Troposphere Sun warms surface, surface radiates Stratosphere Ozone absorbs solar radiation, warming results Mesosphere No ozone, molecules lose more energy than they absorb Thermosphere O2 absorbs solar radiation 18
Composition of atmosphere• Up to 85 km above the • At the earth’s surface, there is a earth’s surface, major balance between production (input) and destruction (output) of component of atmosphere these gases. includes Nitrogen (78%) • N is removed from the and Oxygen (21%) atmosphere primarily by soil bacteria. N is returned to the atmosphere by decaying of organic bodies.
Vertical Structure of Atmosphere• Troposphere: 12 km above • Tropopause: The boundary the earth surface is called separating troposphere from the troposphere where majority of stratosphere is called tropopause. the world’s weather occur. • The height of the tropopause• Temperature of the varies. Generally it is higher in troposphere varies from 15 C summer and lower in winter. (earth surface) to -54 C (at the • In some regions tropopause top). “BREAKS” and it is difficult to• Almost all of the processes of locate. vertical transfer to atmospheric properties through turbulence and mixing occur in the troposphere.• Radiosonde: The instrument that measures the vertical profile of air temperature in the atmosphere up to an approximate elevation of 30 km is called RADIOSONDE.• Pollutants: Human-made (and some natural) impurities in the atmosphere are a nuisance and health hazard. These impurities are called Pollutants. NO2, CO, SO2 and hydrocarbons.
Vertical Structure of Atmosphere• Stratosphere: Between 12 • Tropopause: The boundary and 48 km above the earth separating troposphere from the surface called stratosphere is called tropopause. STRATOSPHERE. • The height of the tropopause• Air temperature begins to varies. Generally it is higher in increase with height , producing summer and lower in winter. a temperature inversion. • In some regions tropopause• The inversion tends to reduce “BREAKS” and it is difficult to the amount of vertical motion in locate. the stratosphere itself; hence it is a stratified layer.• Ozone: Ozone is the reason for the heating of stratosphere, as it absorbs energetic ultraviolet (UV) radiation from the sun.• If ozone were not present, the air probably would become colder with height, as it does in the troposphere.• Ozone Hole: Concentration of ozone in the atmosphere is reducing, creating ozone hole, which caused direct exposure of UV radiation, e.g. in Australia, it is a major concern.
Vertical Structure of Atmosphere• Mesosphere: Vertical layer • Stratopause: The boundary of the atmosphere above the separating stratosphere from the stratosphere is mesosphere. Mesosphere is called Stratopause.• The percentage of N2 and O2 in the mesosphere is about the • The air at this level is very thin same as at the sea level, but and atmospheric pressure is very very low density. (less O2 low 1mb or 1hPa. breathing) • 99.9% of the atmospheric mass is• We need breathing equipments located below stratopause. otherwise prolonged exposure • Temperature: The temperature to such conditions may cause in the mesosphere decreases deficiency of O2 to brain with height up to 85 km, partially leading to Hypoxia. due to lack OZONE. (Less• Exposure to UV solar radiation absorption of solar radiation). may burn the body parts • Temperature of the mesosphere severely. may reach -90 C.
• Thermosphere: The hot • Mesopause: The boundary that layer above the mesosphere is separates colder mesosphere thermosphere. from the warmer thermosphere is called mesopause.• In the thermosphere, oxygen molecules absorbs energetic solar radiation and warm the air.• Absorption of small amount of solar radiation can cause large increase in air temperature.• As the density of thermosphere is very low, air molecules will move over 1 km distance before colliding another molecule.• Similar molecules at the earth’s surface will move an average distance of less than one millionth of a centimeter before it collide another molecule.
• Exosphere: The region • At the top of the thermosphere where atoms and molecules (near exosphere) 500 km above shoot off into space is the earth’s surface, molecules sometimes referred to as the can move distances of 10 km Exosphere. before they collide another molecule.• Exosphere represents the • At this height, many of the lighter, upper limit of the earth’s faster-moving molecules traveling atmosphere. in the right direction escape the earth’s gravitational pull.
Atmospheric composition• Homosphere: Below the • Heterosphere: The region from thermosphere (0-95 km above the base of the thermospher (95+ the earth’s surface) the km) is called heterosphere. composition of air is fairly • In the thermosphere the collision uniform (78% N, 21% O) and between the molecules is well mixed by turbulent. This infrequent and air is unable to region is called Homosphere. mix, therefore atoms and heavier• . molecules (O2 and N2) tend to settle to the bottom of the layer, while lighter gasses (Hydrogen and Helium) float to the top.
Ionosphere• Ionosphere: It is an electrified • The region from the base of the region within the upper thermosphere (95+ km) is called atmosphere where fairly large heterosphere. concentrations of ions and free • Bulk of the ionosphere is in the electrons exist. atmosphere.• Ions are atoms and molecules that • Ionosphere plays a major role in have lost (or gained) one or more AM radio communications. Lower electrons. part (D-region) reflects standard• Atoms lose electrons and become AM radio waves back to the positively charged when they earth. cannot absorb all of the energy transferred to them by a colliding energetic particle of solar energy.• .
Station Plot G2 3 Station Pressure 72 998 Sea-level pressure is plotted in tenths of 9 -16 millibars (mb), with the leading 10 or 9 omitted. For reference, 1013 mb is 45 equivalent to 29.92 inches of mercury. FNL .09 Below are some sample conversions between plotted and complete sea-level pressure values: 410: 1041.0 mb 103: 1010.3 mb 987: 998.7 mb 872: 987.2 mb1 kt = 0.514 ms-1 = 1.15 mph 30
Climate-Water-Food Linkages Climate Wind, Temperature Rainfall Sunshine, CO2 level Solar Radiation GDDand Corresponding GSL Photosynthetic Evapo-transpiration (ET) Activity Crop Water Demand Canal/ground water Water Availability Agriculture (Crop Yield)
RainfallRainfall Monsoon Winter Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Wet Period Dry Period 6 Months (Mar – Aug)…………… Wet Window 6 Months (Sep – Feb)…………… Dry Window
Units, Conversions, and Equations Peta P 1,000,000,000,000,000 1015 Tera T 1,000,000,000,000 1012 Giga G 1,000,000,000 109 Mega M 1,000,000 106 Kilo k 1,000 103 Hecto h 100 102 Deca da 10 101 No Prefix 1 100 Deci d 0.1 10-1 Centi c 0.01 10-2 Milli m 0.001 10-3 Micro µ 0.000001 10-6 Nano n 0.000000001 10-9 Pico p 0.000000000001 10-12 Femto f 0.000000000000001 10-15
Units, Conversions, and EquationsPhysical Quantity Name of SI Unit SymbolLength Meter mMass Kilogram kgTime Seconds sTemperature Kelvin KAmount of substance Mole molElectric current Ampere AQuantity Name Derived Unit MKSForce Newton (N) kg m s-2Pressure Pascal (Pa) (Nm-2) = kg m-1 s-2Energy Joule (J) (Nm) = kg m2 s-2Power Watt (W) (Js-1) = kg m2 s-3
Review Energy Conduction: Energy transfer by molecular collisions E.g.: The sun warms the ground, and this heats a thin layer of air above the surface In general, air is a poor conductor Convection: energy transfer by the motion of matter from one location to another e.g.: parcel of air rising Important in our atmosphere Radiation: transfer of energy not requiring contact between bodies or a fluid between them e.g.: the sun warms the surface of the earth 37