Atmosphere

Importance:

• 1) balance between heat absorbed from Sun and amount that escapes back (extreme temperatures)

• 2) protects Earth from Sun’s harmful rays

Early Atmosphere:

• Volcanoes produced nitrogen and carbon dioxide and little oxygen

• 2 billion years ago simple organisms started making oxygen

Early Atmosphere:

• Ozone layer formed protecting the Earth from Sun’s rays

• Green plants then released more oxygen

Makeup of Atmosphere:

• Nitrogen 78% • Oxygen 21%• Argon• Carbon dioxide 1%• Other gases and water vapor

1) Gases

Gases

• Atmosphere changing because of pollutants increasing CO2

• Pollutants mix with water droplets & chemicals = smog

2 Solids

• Dust• Salt• Pollen

3 Liquids

• Water droplets• Droplets from volcanoes

Troposphere

• All life• Weather occurs• Jets fly here• Lowest layer

Troposphere

• Air pressure greatest near surface decreases as you go up

• Contains ¾ (75%) of atmospheric gases• Nearly all water vapor (99%)• Temperature decreases

Stratosphere

• Jet Stream• Jets fly here to avoid

storms• Temperature increases

Stratosphere

• Ozone layer (O₃)• Protects Earth from

Sun’s harmful rays (UV)• Molecules of ozone

absorb Sun’s energy so as altitude increases; the temperature increases

Mesophere

• Meteor showers (shooting stars)• Temperature decreases

Thermosphere

• Highest temperature• 1st to receive sun’s rays

few molecules• 2 parts: ionosphere &

exosphere

Ionosphere•Temperatures increase

•reflects AM radio waves at night

Ionosphere

• Northern lights

Exosphere

• Space shuttle• Satellites• International

Space Station

• Temperature increases

Importance of Ozone

• Life depends on ozone• 19-48 km above Earth’s surface• Made of 3 atoms of oxygen• Absorbs ultraviolet radiation (UV rays)

Importance of Ozone

• Air pollutants destroying ozone• CFC’s (chlorofluorocarbons)in fridges, air

conditioners, aerosol Sprays, & some foam packing

Chlorine is broken off CFCs by UV rays into regular oxygen that can’t absorb UV rays

•creates a hole in ozone over Antarctica

•increase of UV rays kills life and causes skin cancer

http://www.odec.ca/projects/2008/krol8a2/images/global_warming3.jpg