The atmosphere is composed mainly of nitrogen and oxygen with traces of carbon dioxide, water vapor, and other gases. The atmospheric layers (troposphere, stratosphere, mesosphere, thermosphere, and exosphere) vary around the globe and in response to seasonal changes.
The troposphere is the lowest layer of the EarthΓÇÖs atmosphere, extending to a height of 8-15 km, depending on latitude. The stratosphere, warmer than the upper troposphere, is the next layer and rises to a height of about 50 km. Temperatures in the mesosphere, 50 to 80 km above the Earth, decline with altitude to -70 to -140 Celsius, depending upon latitude and season. Temperatures increase again with altitude in the thermosphere, which begins about 80 km above the Earth. They can rise to 2,000 C. The exosphere begins at 500 to 1,000 km and the few particles of gas there can reach 2,500 C during the day.
