A layer of the atmosphere that lies between about 7 and 31 mi (11 and 50 km) above the earth's surface, bounded at the bottom by the tropopause and at the top by the stratopause. Scientists became aware of the presence of the stratosphere with observations of high level dust after the eruption of Krakatoa in 1883. However, the real discovery of the stratosphere had to await Teisserenc de Bort's work of 1900.

The stratosphere is characterized by temperatures that rise with height. As a result, the air is very stable, not mixing much vertically, and allowing distinct layers of air, or strata, to form. There are also persistent regular strong winds, of which the best known are the intense western winds during the winter called the polar night jet stream.

The air in the stratosphere has much the same composition as the lower atmosphere except for a higher proportion of ozone. Absorption of...