The Atmosphere

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

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?

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

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

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

Picture taken from: http://maps.grida.no/go/graphic/greenhouse-effect