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