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

0-12 km Where we live Weather occurs here As height increases, temperature decreases Temperature drops ~ 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 (~60 o C) 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

Mesoshpere

Mesosphere 50 – 80 km Temperature decrease to -100 o C 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

80 km and up Air very thin Temperatures very high because of sun’s intense UV radiation Temps can be >2000 o C 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 !