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Earths Atmosphere
An envelope of gases that surround the planet
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Lapse Rate= 7C/km
Dry, stable
Logrithmic scale
S tructure of Earths Atmosphere
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Greenhouse
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I f Earths was flat , solar radiation would be the same everywhere
How and Why does Earths Atmosphere Circulate?
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S ummer
Winter
S easons caused by tilt of E arths axis
E arths Tilt also important for distribution of incoming radiation
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Average AL B EDO for whole Earth ~30%
A lbedo is fractionof incoming solar radiation reflected
back to space
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Why is the seasonal change so strong between 45 and 70?
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Low latitude
oceans absorbmore of incomingradiation
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Why does Earths Atmosphere Circulate?
Latitudinal gradient drives atmospheric circulation!
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How does Earths Atmosphere Circulate?
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Warm air can hold much more water than Cold air!
AND: Wet air is less dense than dry air - R IS ES
Saturation Vapor Pressure Curve
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I f Earth didnt spin, Circulation would be simple!
How does Earths Atmosphere Circulate?
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G eneral Atmospheric Circulation
Rotation of E arthcomplicates the picture
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Coriolis Effect
Earths rotation causes points on Equator to move faster
Faster
Faster
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Coriolis Effect
Deflection R IG HT in N. hemisphere, LEFT in S . Hemisphere
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Surface flow of airdeflected like the rocket:
N. Hemisphere mid-latitude winds deflectedright (EA S T).
N. Hemisphere tradesdeflected right(WE S T)
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T ricellular model of atmosphericcirculation explains large scale pattern of deserts on Earth
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H umanInfluence onEarths
AtmosphereACID RAIN
SMOG
OZONE DEPLETION
GLOBAL WARMING
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Compositionof EarthsAtmosphere
Water can be0.3 to 4%
CO2 , CH
4 , NO
2are important TRAC E G ASES
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Human influence onatmospheric chemistry
Atmospheric pollutants dispersed by circulation
Residence time determines impactS hort residence time, regional effects S ulfur dioxide (Acid rain), Nitrogen oxides ( S mog)
Long residence time, global effects Chlorofluorocarbons (Ozone depletion) CO 2, CH 4 - greenhouse warming
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M auna Loa CO 2 record - The Keeling Curve
Global E ffects
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S ynthesis of Northern Hemisphere Temperature Records
The Hockey S tickUsed in 2001 IPCC Report
Gradual cooling --> Unprecedented Warmth
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Effects of Acid Rain on Forests
Nutrient leaching, release of toxic metals
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Acid rain
attackslimestonebuildingsandmonuments
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Stratospheric Ozone
Ozone in the S tratosphere is good ozone Ozone constantly produced/destroyed in
S tratosphere Provides UV shield ( protects from skin cancer)
Chlorofluorocarbons (CFCs) destroy ozone first Cl + O 3 --> ClO + O 2then ClO + O --> Cl + O 2
Global E ffects
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OzoneH oleCl drivenO3 destructionstarts each
spring asS tratospherewarms TO MS
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Fixing Atmospheric PollutionCFCs banned by 13 industrial nations 1989 Annual ozone hole getting smaller, not yet back
to pre-1950s levels
S crubbers added to power plants S O2 converted to Ca S O4 (gypsum)
Reduction in CO 2 emissions OR CO 2 sequestration technologies
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