What is Stratosphere?
The '''stratosphere''' is one of the layers of the [[atmosphere]] of the planet [[Earth]]. It extends from about 8&nbsp;km above the poles (18&nbsp;km above the equator) to about 50&nbsp;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 [[Ultraviolet|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. {{sci-stub}} [[Category:Layers of Earth's atmosphere]]