Wednesday 6 August 2014
The atmosphere of the Earth serves as a key factor in
sustaining the planetary ecosystem. The thin layer of gases that envelops the
Earth is held in place by the planet's gravity. Dry air consists of 78% nitrogen,
21% oxygen, 1% argon and other inert gases, carbon dioxide, etc.; but air also
contains a variable amount of water vapor. The atmospheric pressure declines
steadily with altitude, and has a scale height of about 8 kilometres at the
Earth's surface. Source
