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 only associated with Earth: it occurs on any other planet or moon that has an atmosphere as well.
On Earth, the stratopause is 50 to 55 kilometres (31–34 mi) high above the Earth's surface. The atmospheric pressure is around 1/1000 of the pressure at sea level. The temperature in the stratopause is -15 degrees Celsius (5 degrees Fahrenheit).