The atmosphere - AQA SynergyThe Earth's early atmosphere
The early atmosphere was mainly carbon dioxide and water vapour. Human activities are releasing greenhouse gases which are causing global warming, and other atmospheric pollutants.
The Earth formed approximately 4.6 billion years ago. Scientists cannot be certain about what gases made up the Earth's early atmosphereThe layers of gases that surround the Earth. The important gases in the atmosphere are nitrogen, oxygen and carbon dioxide.. Ideas about how the atmosphere was produced and how it has changed have developed over time as new evidenceInformation or material that shows something is true. has been discovered. There is still not enough evidence for scientists to be certain.
Where did the atmosphere come from?
One theory suggests that the early atmosphere came from intense volcanic eruptionWhen a mountain with a hole in the top expels lava, ash, gas and other materials. activity, which released gases that made the early atmosphere very similar to the atmospheres of Mars and Venus today:
a large amount of carbon dioxide
little or no oxygen
small amounts of other gases, such as ammonia and methane
Volcanic activity also released water
vapourVapour is a cloud of liquid particles. Steam is water vapour., which condensedTurned from a gas or vapour into a liquid, usually as a result of cooling. as the Earth cooled to form the oceans. Nitrogen was probably also released by volcanoes which gradually built up in the atmosphere because it is unreactive.