The Atmosphere

THE ATMOSPHERE

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

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

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

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

Mesoshpere

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

Shooting stars

Thermosphere

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

Magnetosphere

• Earth’s magnetic field• Causes Northern Lights

NORTHERN LIGHTS

Assignment

• Create a foldable of the layers of the atmosphere.

• READ AND FOLLOW THE DIRECTIONS !!!! DO THIS STEP BY STEP !