Definition of Thermosphere

The Earth’s atmosphere is composed of several layers. The thermosphere is defined as the layer which is present above the mesosphere and below the exosphere. In the thermosphere, the molecules are dissociated as a result of ultraviolet radiations and convert into ions. In this way, the thermosphere constitutes a large proportion of the ionosphere.


The thermosphere originates at 80 km above sea level. The temperature of this level increases as the altitude increases. This is because there is higher absorption of solar radiations and the temperature can even rise to 1700 degrees Celsius or more. The density of the gas is very low in the thermosphere hence the molecules are unable to conduct heat and the overall inside temperature remains very low.

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