The mesosphere, which is the third innermost layer of the Earth's atmosphere, is comprised largely of nitrogen, oxygen and carbon dioxide. Its chemical composition differs very little from that of the innermost layers of atmosphere, with the approximate composition being 79 percent nitrogen, 20 percent oxygen and 1 percent carbon dioxide and other trace gases. The density of these gases is lower in the mesosphere than in the lower atmosphere.
The mesosphere is found from approximately 31 miles to 53 miles above the Earth's surface. Partially due to the low density of gas molecules here, the temperature often dips as low as -130 degrees F. Temperature decreases further away from the Earth's surface.
Because of the low temperatures and the presence of combustible gases in the mesosphere, meteors slow down when they enter this layer of the atmosphere. Their reaction with the oxygen in the atmosphere leaves behind a fiery trail that is sometimes seen from Earth. Iron and other metal ions are also created as a result of this process, so the mesosphere has a higher ionic content than other atmospheric layers. Occasionally, this causes clouds of ions to form near the poles. These polar mesospheric clouds emit charges in a manner similar to lightning.