Layer 4: Thermosphere
The fourth layer of the atmosphere, or upper atmosphere, is called the thermosphere. This layer is between approximately 80 km and 500 km above the surface.
Like the mesosphere, this layer also contains gases including oxygen molecules but here they become even rarer as the distance from Earth increases. The International Space Station orbits in the thermosphere.
An interesting aspect of the thermosphere is that radiation cause particles to become electrically charged, or ionized. The thermosphere is where auroras occur.
In contrast to the mesosphere, the temperatures in the thermosphere are higher and increase with altitude. Temperatures increase with height because—although molecules are rare they are moving very rapidly. Temperature is a measure of molecular motion.