The stratopause is the level of the atmosphere which is the boundary between two layers, stratosphere and the mesosphere. In the stratosphere the temperature increases with altitude, and the stratopause is the section where a maximum in the temperature occurs.

This occurs not only on Earth, but on other planets with an atmosphere as well.

On Earth, the stratopause is 50 to 55 km high above the Earth's surface. The atmospheric pressure is around 1/1000th of the pressure at sea level.