Earth's atmosphere

Earth's atmosphere is the layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly 78% nitrogen and 21% oxygen, with trace amounts of other gases. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night.

Temperature and the atmospheric layers

The temperature of the Earth's atmosphere varies with altitude; the mathematical relationship between temperature and altitude varies between the different atmospheric layers:

Related Topics:
Temperature - Altitude - Mathematical relationship

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• troposphere: From the Greek word tropos meaning to turn or mix. The troposphere is the lowest layer of the atmosphere starting at the surface going up to between 7 km at the poles and 17 km at the equator with some variation due to weather factors. The troposphere has a great deal of vertical mixing due to solar heating at the surface. This heating warms air masses, which then rise to release latent heat as sensible heat that further buoys the air mass. This process continues until all water vapor is removed. In the troposphere, on average, temperature decreases with height due to expansive cooling.
• stratosphere: from that 7–17 km range to about 50 km, temperature increasing with height.
• mesosphere: from about 50 km to the range of 80 km to 85 km, temperature decreasing with height.
• thermosphere: from 80–85 km to 640+ km, temperature increasing with height.

The boundaries between these regions are named the tropopause, stratopause, and mesopause.

Related Topics:
Tropopause - Stratopause - Mesopause

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The average temperature of the atmosphere at the surface of earth is 14 °C.

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Various atmospheric regions

Atmospheric regions are also named in other ways:

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• ionosphere — the region containing ions: approximately the mesosphere and thermosphere up to 550 km.
• exosphere — above the ionosphere, where the atmosphere thins out into space.
• magnetosphere — the region where the Earth's magnetic field interacts with the solar wind from the Sun. It extends for tens of thousands of kilometers, with a long tail away from the Sun.
• ozone layer — or ozonosphere, approximately 10 - 50 km, where stratospheric ozone is found. Note that even within this region, ozone is a minor constituent by volume.
• upper atmosphere — the region of the atmosphere above the mesopause.
• Van Allen radiation belts — regions where particles from the Sun become concentrated.