Category Archives: Earth’s atmosphere

Earth’s atmosphere

Composition of air For 200 million years, the proportions of different gases in the atmosphere are similar to those today: ■ 78.1% nitrogen ■ 20.9% oxygen ■ other gases: carbon dioxide (0.04%), water vapour (0.25%) and argon (0.9%). The density of air at sea level is about 1.2 kg/m3 (1.2 g/L). Origin of atmosphere There are several theories about how the atmosphere was formed. 1. Earth

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