Composition of the Earth's atmosphere

The composition of air

You need to know the proportions of the main gases in the atmosphere.

The Earth's atmosphere has remained much the same for the past 200 million years. The pie chart shows the proportions of the main gases in the atmosphere.

It is clear that the main gas is nitrogen. Oxygen - the gas that allows animals and plants to respire [respire: to engage in respiration - the energy-producing process inside living cells ], and fuels to burn - is the next most abundant gas. These two gases are both elements and account for about 99% of the gases in the atmosphere.

The remaining gases, such as carbon dioxide, water vapour and noble gases such as argon, are found in much smaller proportions.