The stratopause (formerly mesopeak) is the level of the atmosphere which is the boundary between two layers: the stratosphere and the mesosphere. In the stratosphere, the temperature increases with altitude, and the stratopause is the region where a maximum in the temperature occurs. This atmospheric feature is not exclusive to Earth, but also occurs on any other planet or moon with an atmosphere.^[1] According to James Kasting, planets whose atmospheres do not absorb shortwave sunlight, such as Venus and Mars, do not have a Stratosphere and thus have no Stratopause.^[2]

On Earth, the stratopause is 47–51 km (29–32 mi) above sea level. The atmospheric pressure is around 1⁄1000 of the pressure at sea level. The temperature in the stratopause is −2.5 °C (27.5 °F).^[3]