Stratosphere

The stratosphere is one of the layers of the atmosphere of the planet Earth. It extends from about 8 km above the poles (18 km above the equator) to about 50 km. In the stratosphere, the temperature rises with increasing height. This makes the stratosphere very stable. This temperature gradient is caused by the ozone layer which absorbs some UV radiation from sunlight. The absorbed radiation is converted to heat.

This differs from the lower layer, the troposphere, where temperature declines with higher altitude, and from the next higher layer, the mesosphere, where the temperature again declines.

Airplanes that are going far usually fly in the lower stratosphere, because the engines are more efficient in cold air and drag is small in low air density air.

Stratosphere Media

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  Afterglow of the troposphere (orange), the stratosphere (blue) and the mesosphere (dark) at which atmospheric entry begins, leaving smoke trails, such as in this case of a spacecraft reentry.

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  This image shows the temperature trend in the lower stratosphere as measured by a series of satellite-based instruments between January 1979 and December 2005. The lower stratosphere is centered around 18 kilometers above Earth's surface. The stratosphere image is dominated by blues and greens, which indicates a cooling over time.

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  Diagram showing the five primary layers of the Earth's atmosphere: exosphere, thermosphere, mesosphere, stratosphere, and troposphere. The layers are not to scale.

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  Lightning extending above the troposphere into the stratosphere as blue jet and reaching into the mesosphere as red sprite.