Download - Atmosphere
The AtmosphereThe Atmosphere
Structure and ChangeStructure and Change
OverviewOverview
StructureStructure Compositional structureCompositional structure Temperature structureTemperature structure Functional structureFunctional structure
ChangeChange Natural sources of changeNatural sources of change Natural influences on Natural influences on
pollutionpollution Anthropogenic pollutionAnthropogenic pollution
GeneralGeneral Thermopause is considered the outermost boundary Thermopause is considered the outermost boundary
of the atmosphere.of the atmosphere. 480km, 300 mi above surface480km, 300 mi above surface
The Exosphere extends beyond the thermopauseThe Exosphere extends beyond the thermopause Rarefied (near vacuum)Rarefied (near vacuum) Sparse Hydrogen and Helium atomsSparse Hydrogen and Helium atoms Extends to 20,000 miles (32,000 km) from Earth’s surfaceExtends to 20,000 miles (32,000 km) from Earth’s surface
Density of Atmosphere increases near the surfaceDensity of Atmosphere increases near the surface 90% of atmospheric mass occurs within 16,000 meters of 90% of atmospheric mass occurs within 16,000 meters of
surfacesurface Air pressure (sea level): 1013.2 mb; 101.32 kPa; 29.92 inAir pressure (sea level): 1013.2 mb; 101.32 kPa; 29.92 in
Air pressure decreases with decreasing density (i.e., altitude)Air pressure decreases with decreasing density (i.e., altitude)
Atmospheric gases held by Earth’s Atmospheric gases held by Earth’s gravitygravity Earth’s gravity weakens with altitudeEarth’s gravity weakens with altitude Changes density profileChanges density profile Sorts atmosphere into different layersSorts atmosphere into different layers
Three different ways of looking at Three different ways of looking at atmospheric layeringatmospheric layering CompositionComposition
HomosphereHomosphere HeterosphereHeterosphere
TemperatureTemperature Troposphere (Tropopause)Troposphere (Tropopause) Stratosphere (Stratopause)Stratosphere (Stratopause) Mesosphere (Mesopause)Mesosphere (Mesopause) Thermosphere (Thermopause)Thermosphere (Thermopause)
FunctionFunction OzonosphereOzonosphere IonosphereIonosphere
CompositionComposition HomosphereHomosphere
Gases evenly Gases evenly mixedmixed
ExceptionsExceptions Water vapor Water vapor
(clouds)(clouds) Ozone layer Ozone layer Point sources at Point sources at
surfacessurfaces Over 99% of Over 99% of
AtmosphereAtmosphere HeterosphereHeterosphere
Uneven mixture Uneven mixture of gases, sorted of gases, sorted by atomic and by atomic and molecular weightmolecular weight
TemperatureTemperature TroposphereTroposphere 90% of Atmosphere90% of Atmosphere
Nearly all of the water vapor and weatherNearly all of the water vapor and weather Supports lifeSupports life Upper boundary: TropopauseUpper boundary: Tropopause
18 km (11mi) at equator, 12 km (8 mi) mid-18 km (11mi) at equator, 12 km (8 mi) mid-latitudes, 8 km (5 mi) at poleslatitudes, 8 km (5 mi) at poles
Varies with temperature (solar heating)Varies with temperature (solar heating) Temperatures decrease with altitudeTemperatures decrease with altitude
Normal Lapse Rate: 6.4Normal Lapse Rate: 6.4ooC/km (3.5C/km (3.5ooF/ft)F/ft) Environmental Lapse RateEnvironmental Lapse Rate InversionsInversions Crucial for understanding weatherCrucial for understanding weather Heated by the Earth’s surfaceHeated by the Earth’s surface
StratosphereStratosphere MesosphereMesosphere ThermosphereThermosphere
StratosphereStratosphere 18 – 50 km (11 –31 mi) above surface18 – 50 km (11 –31 mi) above surface Ozone layerOzone layer Temperature increases with altitudeTemperature increases with altitude
Heating from absorption of ultraviolet light by Heating from absorption of ultraviolet light by ozoneozone
At lower levels, heated by surface emanations as At lower levels, heated by surface emanations as wellwell
Upper boundary: StratopauseUpper boundary: Stratopause MesosphereMesosphere
50 – 80km (30 – 50 mi) above surface50 – 80km (30 – 50 mi) above surface Temperature decreases with altitudeTemperature decreases with altitude Upper boundary: MesopauseUpper boundary: Mesopause
Coldest region in atmosphereColdest region in atmosphere Emanations from the stratosphere provide heat Emanations from the stratosphere provide heat
sourcesource
ThermosphereThermosphere 80 – 480 km (50-300 mi) on average80 – 480 km (50-300 mi) on average Upper Boundary: ThermopauseUpper Boundary: Thermopause
Actual altitude varies between 250 – 550 km Actual altitude varies between 250 – 550 km (155 – 340 mi)(155 – 340 mi)
Increases with increased solar activityIncreases with increased solar activity
Extremely high temperatures but little Extremely high temperatures but little sensible heatsensible heat
Heated by direct exposure to incoming solar Heated by direct exposure to incoming solar radiationradiation
Air particles have extremely high kinetic energy Air particles have extremely high kinetic energy (temperature)(temperature)
Low density of particles means fewer collisions Low density of particles means fewer collisions of particles, lower overall capacity to store heatof particles, lower overall capacity to store heat
FunctionFunction Classifies atmospheric layers Classifies atmospheric layers
according to how they shield the according to how they shield the surface from harmful radiationsurface from harmful radiation
OzonosphereOzonosphere OO33
Absorbs short-wave radiation and Absorbs short-wave radiation and reradiates it as long-wave radiationreradiates it as long-wave radiation
Shields surface from harmful Shields surface from harmful ultraviolet radiationultraviolet radiation
Various pollutants deplete ozoneVarious pollutants deplete ozone IonosphereIonosphere
OzonosphereOzonosphere IonosphereIonosphere
Absorbs short-Absorbs short-wave radiationwave radiation
Cosmic rays, Cosmic rays, Gamma rays, X-Gamma rays, X-rays, shorter UVrays, shorter UV
High energy High energy radiation tends radiation tends to knock to knock electrons off of electrons off of the atmospheric the atmospheric gas atoms, gas atoms, producing producing positively positively charged ionscharged ions