the atmosphere
Post on 01-Jan-2016
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Definition: Atmosphere
• Air that surrounds the earth
• Composed of:– Nitrogen 78%– Oxygen 21%– Misc. Gases (water vapor, argon, etc… 1%)
How did it form?
• THEORY ……….• As earth cooled, released gases from the
earth’s interior• Not the same composition as today’s
atmosphere
Benefits of Atmosphere
• Provides gases necessary for life (oxygen, carbon dioxide)
• Protects us from majority of suns harmful UV radiation
• Allows light to reach surface for energy and photosynthesis
• Radiates some heat back to Earth, therefore warming the planet
Layers
• Defined by changes in temperature• Troposphere– tropopause
• Stratosphere–stratopause
• Mesosphere–mesopause
• Thermosphere
Troposphere
• 0-12 km • Where we live• Weather occurs here• As height increases, temperature decreases• Temperature drops ~ 6.50 C/km above Earth’s
surface• Greatest amount of air pressure (weight of air
above)
Tropopause
• Top of troposphere• Temperature fairly constant• Separates troposphere from stratosphere• Where jet stream is– Very strong winds that blow eastward
Stratosphere
• 12 – 50 km• Lower part’s temperature is constant (~60oC)• Contains ozone layer• People can’t breathe in this layer• Lowest part of stratosphere there is less
turbulence so where commercial airlines usually fly!
Ozone Layer
• Earth’s shield• Protects Earth’s surface from the sun’s harmful
UV radiation• It absorbs the sun’s UV radiation• Causes an increase in temperature in upper
part of stratosphere
Mesosphere
• 50 – 80 km• Temperature decrease to -100oC• Coldest region of atmosphere– This is due to the gases in this layer can’t absorb
any of the suns energy (therefore, really cold)• Protects earth from ‘meteorites’ • Meteorites burn up in this area creating
“shooting stars” effect
Thermosphere
• 80 km and up• Air very thin• Temperatures very high because of sun’s
intense UV radiation• Temps can be >2000oC• Has 2 sub-layers– Ionoshpere– exosphere
Ionosphere
• 80 km – 550 km• Contains charged “ionic” particles• Where radio waves are bounced back from
Exosphere
• > 550 km.• Air extremely thin• Area where satellites orbit• Enter space once exit exosphere
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