Chapter 3
Air: It is the breath of life! The earth has a blanket of air! Earth is the only known planet with an atmosphere that can support life. The atmosphere is a blanket of gases surrounding the earth. Atmosphere: What does it contain? Two gases make up the bulk of the earth's atmosphere by volume: nitrogen(78 per cent) and oxygen(21 per cent). The remaining one per cent is composed of' 'trace' gases, the most prevalent of which is argon. The rest of the trace gases, although present in only minute amounts, are very important to life on earth.Two in particular, carbon dioxide and ozone, have a large impact on atmospheric processes.Another gas, water vapour, also exists in small amounts. It varies in concentration from being almost non-existent over desert regions to about 4 per cent over the oceans. Water vapour is important in the formation of weather. The atmosphere has fo...