Earth's thermosphere, which consists of both the ionosphere and the exosphere, feels cold because of the low density of air at that level. Measurements of air temperature reveal how energetic the measured particles are, but with so few particles, the thermosphere is unable to effectively transfer heat. read more
The thermosphere is the biggest layer of the earth’s atmosphere and is located above the mesosphere and below the exosphere. Ultraviolet radiation causes ionization in the thermosphere. The thermosphere is located from about 80 kilometres (50 mi) to 500 kilometres (310 mi) above the earth’s surface. read more