Background Information: Thermosphere
Characteristics:
- Altitude: Above the mesosphere, the thermosphere can extend to an altitude of -400 kilometers or even higher to -500 kilometers.
- Composition: The molecules of many of the gases are separated into their individual atoms by the action of the ultraviolet and X-radiation from the sun. The regions where ionization is more persistent in the thermosphere and the mesosphere are called the ionosphere.
- Temperature: At the lower part of the thermosphere, temperature can be as low as -40 degrees Celsius. Gradually, the temperature rises and increases to more than 100 degrees Celsius with the increase in altitude. During active periods of the sun this increase may extend to an altitude of -500 kilometers. This layer is heated by the sun from above.



