1. The Atmosphere

2. Characteristics All gases that surround the Earth, called air
Altitude extends to ~80 km above the surface
Most abundant elements:
nitrogen, oxygen, argon
Most abundant compounds:
Carbon dioxide (CO2), water vapor (H2O)
Characteristics

3. Nitrogen Cycle - moves nitrogen from the air, to soil, to plants and animals, and back to air.
Nitrogen is removed from the air by nitrogen-fixing bacteria that live in the soil and on plant roots
Why all that Nitrogen?

4. Ozone A molecule with 3 oxygen atoms
Absorbs harmful UV radiation from the sun
Chlorofluorocarbons, or CFC’s, break down ozone
Ozone

5. Layers of the Atmosphere
Troposphere – where most weather occurs; most H20 and CO2 is here
Stratosphere – includes the ozone layer
Mesosphere – where meteorites burn up
Thermosphere - high energy rays from the sun are absorbed by N2 and O2 here; hottest layer
Exosphere - Molecules from atmosphere escape into space; satellites orbit here.
Layers of the Atmosphere

7. The gases in Earth’s atmosphere slow the escape of energy that radiates from Earth’s surface.
Gases: carbon dioxide, methane, water vapor, nitrous oxide, fluorocarbons
Some heat escapes into space
Greenhouse gases trap some heat
Sunlight
Earth’s Surface
Atmosphere
The Greenhouse Effect

8. Picture taken from: