Stratosphere

Stratosphere is the second major layer of Earth's atmosphere, lying above the troposphere and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler higher up and warmer farther down.

The border of the troposphere and stratosphere, the tropopause, marks where this temperature inversion begins. Near the equator, the stratosphere starts at 18 km (59,000 ft; 11 mi); at mid latitudes, it starts at 10–13 km (33,000–43,000 ft; 6.2–8.1 mi) and ends at 50 km (160,000 ft; 31 mi); at the poles, it starts at about 8 km (26,000 ft; 5.0 mi).

The stratosphere is the location of the ozone layer, a part of Earth's atmosphere that contains relatively high concentrations of that molecule. The concentration of ozone in the Earth's atmosphere is typically less than 10 parts per million, but the majority of it is located in the stratosphere, with the peak concentration occurring at about 25 kilometres (16 mi) above the Earth's surface.

Composition

The stratosphere is composed of a mixture of gases, predominantly oxygen and nitrogen. The concentration of ozone in the stratosphere is much higher than in the troposphere. The stratosphere also contains a small amount of other gases, including argon, carbon dioxide, neon, and helium.

Ozone layer

The ozone layer is a region of the stratosphere containing a high concentration of ozone. It absorbs most of the Sun's ultraviolet (UV) radiation, and it is because of this that the stratosphere is warmer than the upper troposphere.

Stratospheric circulation

The circulation of the stratosphere is a part of the large-scale atmospheric circulation. It is characterized by slow, large-scale upward motion of air in the tropics, poleward motion of air in the middle latitudes, and downward motion of air at the poles.

See also

• Atmosphere of Earth
• Ozone depletion
• Ozone layer
• Troposphere

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