The region of the atmosphere extending from the top of the troposphere (the tropopause), at heights of roughly 10–17 km, to the base of the mesosphere (the stratopause), at a height of roughly 50 km. The stratosphere is characterized by constant or increasing temperatures with increasing height and marked vertical stability. It owes its existence to heating of ozone by solar ultraviolet radiation.

The “inversion layer” is the layer through which the temperature increases with increasing altitude. The lowest altitude of the inversion layer is the “base of the inversion".

Surface inversion, or ground inversion, is a temperature inversion based at the earth's surface. The surface inversion is due primarily to greater radiative loss of heat at and near the surface than at levels above. Thus, surface inversions are common over land prior to sunrise and in winter over high-latitude continental interiors.