The stratopause is an atmospheric layer that extends from approximately 48 to 50 kilometers above the Earth's surface. In this layer temperature remains constant (isothermal). 


Atmospheric layer found at an average altitude of 20 to 48 kilometers above the Earth's surface. Within the stratosphere exists the ozone layer. Ozone's absorption of ultraviolet sunlight causes air temperature within the stratosphere to increase with altitude. 


Atmospheric layer found between the stratosphere and the thermosphere. Usually located at an average altitude of 50 to 80 kilometers above the Earth's surface. 


Isothermic layer at the top of the mesosphere. This boundary layer in between the mesosphere and the thermosphere is usually found at an average altitude of 85 kilometers. Coldest temperatures in the atmosphere are found here.

The Mesosphere
25 miles (40km) above the earth's surface marks the transition to the mesosphere. In this layer, temperature once again begins to fall as altitude increases, to temperatures as low as -225deg.F (-143deg.C) near its top, 50 miles (81km) above the earth. Such extreme cold allows the formation of so-called noctilucent clouds, thought to be made of ice crystals clinging to dust particles.

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