What are the distinguishing characteristics of the thermosphere?
An increase in temperature.
The thermosphere is very high above the Earth and is distinguished by an increase in temperature with altitude. The density of the air is extremely low, but the activity of the molecules are very high due to the amount of energy they are receiving from the sun. Individual molecules can be as warm as 2000 degrees C.
An interesting fact is that anyone in this part of the atmosphere would not feel the heat as the molecules are so far apart it is almost a vacuum.