Atmosphere of Earth
Atmosphere of Earth
The Atmosphere of Earth is a layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation).
Etymology
The word "atmosphere" comes from the Greek words "atmos", meaning vapor, and "sphaira", meaning sphere.
Composition
The atmosphere of Earth is composed of nitrogen (about 78%), oxygen (about 21%), argon (about 0.9%) with carbon dioxide and other gases making up the remaining 0.1%. The atmosphere also contains a variable amount of water vapor, on average around 1%.
Layers
The atmosphere of Earth can be divided into a number of layers, each with distinct properties. These include the Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere.
Related Terms
- Greenhouse effect: The process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere.
- Ozone layer: A region of Earth's stratosphere that contains a high concentration of ozone molecules.
- Air pressure: The force exerted onto a surface by the weight of the air above it.
See Also
References
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