TAMU GEOG 203 - Earth’s Atmosphere

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GEOG 203 Planet Earth Topic 3 Earth s Atmosphere GEOG 203 Planet Earth R Compounds of the atmosphere Atmospheric pressure R Profile of the atmosphere Composition Temperature Function R Variable components Natural pollution Anthropogenic pollution STS 130 Endeavour 9 February 2010 GEOG 203 Planet Earth Earth s Atmosphere R Atmosphere is a very thin layer of gases If earth size of an apple atmosphere thickness of the skin R Without it no life on earth protective filter maintains temperature GEOG 203 Planet Earth Composition of the Inner Atmosphere Carbon dioxide CO2 Argon Ar 0 9 Trace gases 0 041 Oxygen O2 Nitrogen N2 N2 O2 Ar 78 21 0 9 99 9 GEOG 203 Planet Earth Atmospheric Pressure Lower density Higher density R All of the gases are held down by gravity Gravity compresses air denser near the surface Air thins rapidly with altitude GEOG 203 Planet Earth Atmospheric Pressure R 50 of atmospheric mass is in bottom 5 5 km 3 4 mi R 99 9 is below 50 km 31 mi GEOG 203 Planet Earth Atmospheric Pressure km R decreases exponentially with height highest at sea level R Sea level pressure 1 kg cm2 14 psi 29 92 in Hg 1013 25 mb 1013 25 mb mi 5 GEOG 203 Planet Earth Atmospheric Profile R Atmosphere extends to 32 000 km 20 000 mi from surface Exosphere extremely few hydrogen and helium atoms are R Thermosphere 480 km 300 mi top of principal still held by gravity atmosphere R Three ways to examine atmosphere 1 Composition 2 Temperature 3 Function GEOG 203 Planet Earth 1 Atmospheric Composition R Heterosphere outer atmosphere Gases sorted by gravity heterogeneous stratified by atomic weight Begins at 80 km 50 mi and goes up 0 001 of the atmosphere R Homosphere inner atmosphere Gases evenly mixed concentrations are homogenous 78 N2 21 O2 etc Extends from surface to 80 km 50 mi GEOG 203 Planet Earth 2 Atmospheric Temperature R Thermosphere 80 km 50 mi outward Coincides with heterosphere Temperature very high 2200 F but very little heat R Mesosphere 50 to 80 km 30 to 50 mi Temperature decreases upward lowest temperatures in the atmosphere 90 C 130 F Top of the mesosphere mesopause Thermosphere Mesosphere GEOG 203 Planet Earth 2 Atmospheric Temperature R Stratosphere 18 to 50 km 11 to 31 mi Temperature increases upward 57 C 70 F at bottom but 0 C 32 F at the top stratopause Why so warm Ozone R Troposphere Thermosphere Extends from surface to 18 km 11 mi Temperature decreases at rate of 6 4 C km 3 5 F 1000 ft Where virtually all weather occurs Top tropopause but its height varies Mesosphere Stratosphere Troposphere GEOG 203 Planet Earth Tropopause Height R Thickness of troposphere varies by latitude equator 18 km poles 8 km and by season Troposphere thicker when where temperature is higher GEOG 203 Planet Earth Profiles of Atmosphere GEOG 203 Planet Earth 3 Atmospheric Function R Ionosphere Spans across meso thermosphere Changes incoming particles from atoms to ions where auroras occur Absorbs cosmic rays gamma rays X rays some UV rays R Ozonosphere Part of stratosphere What s so important about ozone Ionosphere Ozonosphere GEOG 203 Planet Earth Ozone O3 R Photodissociation O2 light O O O O2 O3 R Ozone absorbs UV radiation O3 UV O2 O Endless process that absorbs most of the harmful UV radiation Heats the stratosphere why temperature increases in stratosphere GEOG 203 Planet Earth What about the Ozone Hole GEOG 203 Planet Earth Ozone Hole R Not actually a hole but a thinning of the O3 layer R Ozone layer normally 3 mm 0 1 in thick 300 DU R Over Antarctica R Seasonal occurrence biggest around Sep Oct R But synthetic compounds from refrigerants propellants and solvents also end up in the stratosphere Chlorofluorocarbons CFCs GEOG 203 Planet Earth Ozone Hole R UV radiation strips chlorine Cl off CFCs Cl then bonds with O Cl O ClO ClO O Cl O2 R Chlorine used and re used One Cl atom can destroy as many as 100 000 O3 molecules GEOG 203 Planet Earth https svs gsfc nasa gov 31253 GEOG 203 Planet Earth September 17 1979 1 1 106 km2 September 24 2006 October 5 2022 24 5 106 km2 28 3 106 km2 Source https ozonewatch gsfc nasa gov Bigger Hole Halley Surface Observatory TOMS OMI OMPS satellites R Montreal Protocol 1987 has reduced and phased out the use of CFCs Ozone hole may be getting smaller could be recovering GEOG 203 Planet Earth Smaller Hole GEOG 203 Planet Earth Protective Atmosphere Ultraviolet GEOG 203 Planet Earth GEOG 203 Planet Earth UV Index College Station TX January 30 2024 GEOG 203 Planet Earth Variable Atmospheric Components R In addition to N2 O2 etc atmosphere also contains variable gases carbon dioxide monoxide methane sulfur particles smoke ash dust pollen salt chemicals smog R Where do they come from 1 Naturally emitted 2 Transported 3 Anthropogenic sources GEOG 203 Planet Earth 1 Naturally emitted Table Sources of Natural Pollutants GEOG 203 Planet Earth Particles in Stratosphere June 15 1991 Mt Pinatubo erupts 1 mo 3 mo 2 5 yr GEOG 203 Planet Earth August 8 1991 STS 43 Atlantis GEOG 203 Planet Earth The Global Pulse of Fire 2000 2023 https earthobservatory nasa gov global maps MOD14A1 M FIRE GEOG 203 Planet Earth Saharan Dust GEOG 203 Planet Earth 2 Transported Saharan Dust South America Africa https earthobservatory nasa gov images 146913 a dust plume to remember GEOG 203 Planet Earth A Dust Plume to Remember June 2020 GEOG 203 Planet Earth Arctic Haze GEOG 203 Planet Earth A Year in the Life of Earth s CO2 http www youtube com watch v x1SgmFa0r04 GEOG 203 Planet Earth 3 Anthropogenic Pollution R Anthropogenic human caused R Small particles of dust soot and pollution aerosols from urban industrial pollution agricultural fires burning NASA MODIS AOD GEOG 203 Planet Earth Carbon Monoxide CO GEOG 203 Planet Earth Photochemical Smog GEOG 203 Planet Earth Smog and Haze GEOG 203 Planet Earth R NO2 concentrations January 1 20 2020 motor vehicles power plants and industrial facilities R January 23 2023 COVID 19 quarantine January 1 20 2020 February 10 25 2020 GEOG 203 Planet Earth Anthropogenic Pollution Automobiles account for 50 60 of anthropogenic air pollution GEOG 203 Planet Earth Factors That Affect Air Pollution R Local and regional landscapes Volcanic landscapes Mountain barriers Valleys GEOG 203 Planet Earth Volcanic Landscapes Volcanic Smog Vog Hawaii GEOG 203 Planet Earth Mountain Barriers Denver CO GEOG 203 Planet Earth Valleys Temperature Inversion R Temperature normally decreases throughout troposphere Inversion layer layer where temperature suddenly increases GEOG 203 Planet Earth

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TAMU GEOG 203 - Earth’s Atmosphere

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