 Mostly made of nitrogen gas & oxygen gas

Gases that absorb and re-emit infrared radiation  Water vapour  Carbon dioxide  Methane  Nitrous oxide  Ozone  CFCs

 Source: adds greenhouse gases to the atmosphere  Sink: absorbs greenhouse gases from the atmosphere  Natural or caused by human activities

 Natural sources include volcanic eruptions & cellular respiration

 Produced naturally by nitrogen-fixing bacteria

 Ozone (O 3 ) is located in the stratosphere & makes up the ozone layer which blocks harmful UV radiation  Ozone hole in Antarctic  Ground-level ozone forms smog

 Leading cause of ozone depletion in the ozone layer

 Human activities have significantly increased levels of greenhouse gases since 1750

 Increase in global average temperatures

 Ability of a substance to warm the atmosphere by absorbing thermal energy  The contribution of a particular gas to global warming depends on: the concentration of the gas in the atmosphere the ability of the gas to absorb heat the length of time the gas remains in the atmosphere

 Read page 331  Complete Gizmo on Greenhouse Effect  Page 332 #3, 4, 8