GEOLOGY

Detailed explanation-1: -Thermosphere is the hottest layer of the atmosphere while Mesosphere is the coldest layer of the atmosphere. Solar activity strongly influences temperature in the thermosphere, the temperature of this layer can rise as high as 1500 °C.

Detailed explanation-2: -In this layer, UV rays cause ionization and the temperature increases with altitude here due to absorption of solar radiation, making it the hottest. We can understand from the above discussion that the thermosphere has the highest level of absorption of high energy solar radiation, making it the hottest.

Detailed explanation-3: -The thermosphere is the layer in the Earth’s atmosphere directly above the mesosphere and below the exosphere. Within this layer of the atmosphere, ultraviolet radiation causes photoionization/photodissociation of molecules, creating ions; the thermosphere thus constitutes the larger part of the ionosphere.