The Earth's early atmosphere
The Earth formed about 4.5 billion years ago. Scientists believe that its early The layers of gases that surround the Earth. The important gases in the atmosphere are nitrogen, oxygen and carbon dioxide. was produced by volcanic activity.
A volcano in Iceland
Composition of the early atmosphere
The early atmosphere probably contained:
- a large amount of carbon dioxide
- water vapour
- small amounts of other gases
As the Earth began to cool, water vapour Condensation is a change of state in which gas becomes liquid by cooling. formed the oceans. This process can be explained by the The scientific theory used to explain the properties of solids, liquids and gases. It involves the arrangement and movement of the particles in a substance..
Formation of the modern atmosphere
Over time:
- the oxygen levels increased
- the carbon dioxide levels decreased
The composition of the modern atmosphere