Why the upper atmosphere is cooled while it's kinetic temperature is of the order of 1000 K.

The quantity of heat content of an individual molecule in the upper atmosphere is increased about 3.5 times more than that at the earth's surface. Kinetic temperature on earth surface is about 300 K, while in the upper atmosphere it is of the order of 1000 K. But the pressure and hence the density is very low in the upper atmosphere ,i.e.,in the upper atmosphere the number of molecules per c.c. is very small. Thus obviously the total heat content in the upper atmosphere is very small as compared to the heat content on the earth in the same volume of the gas. The result the heat content of the upper atmosphere is very low.