The Earth's early atmosphere
The Earth formed about 4.5 billion years ago. Scientists believe that its early atmosphere 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 condensed formed the oceans. This process can be explained by the particle model.
Formation of the modern atmosphere
- the oxygen levels increased
- the carbon dioxide levels decreased