<P> The thermosphere is the layer of the Earth 's atmosphere directly above the mesosphere . The exosphere is above that but is a minor layer of the atmosphere . Within this layer of the atmosphere , ultraviolet radiation causes photoionization / photodissociation of molecules , creating ions in the ionosphere . The radiative properties of UV rays cause an imbalance of positive and negative energy , creating ions . Taking its name from the Greek θερμός ( pronounced thermos ) meaning heat , the thermosphere begins about 85 kilometres ( 53 mi ) above the Earth . At these high altitudes , the residual atmospheric gases sort into strata according to molecular mass ( see turbosphere ) . Thermospheric temperatures increase with altitude due to absorption of highly energetic solar radiation . Temperatures are highly dependent on solar activity , and can rise to 2,000 ° C ( 3,630 ° F ) . Radiation causes the atmosphere particles in this layer to become electrically charged ( see ionosphere ) , enabling radio waves to be refracted and thus be received beyond the horizon . In the exosphere , beginning at 500 to 1,000 kilometres ( 310 to 620 mi ) above the Earth 's surface , the atmosphere turns into space , although by the criteria set for the definition of the Kármán line , the thermosphere itself is part of space . </P>
<P> The thermosphere is the layer of the Earth 's atmosphere directly above the mesosphere . The exosphere is above that but is a minor layer of the atmosphere . Within this layer of the atmosphere , ultraviolet radiation causes photoionization / photodissociation of molecules , creating ions in the ionosphere . The radiative properties of UV rays cause an imbalance of positive and negative energy , creating ions . Taking its name from the Greek θερμός ( pronounced thermos ) meaning heat , the thermosphere begins about 85 kilometres ( 53 mi ) above the Earth . At these high altitudes , the residual atmospheric gases sort into strata according to molecular mass ( see turbosphere ) . Thermospheric temperatures increase with altitude due to absorption of highly energetic solar radiation . Temperatures are highly dependent on solar activity , and can rise to 2,000 ° C ( 3,630 ° F ) . Radiation causes the atmosphere particles in this layer to become electrically charged ( see ionosphere ) , enabling radio waves to be refracted and thus be received beyond the horizon . In the exosphere , beginning at 500 to 1,000 kilometres ( 310 to 620 mi ) above the Earth 's surface , the atmosphere turns into space , although by the criteria set for the definition of the Kármán line , the thermosphere itself is part of space . </P>
the source of heating in the thermosphere is the absorption of
the source of heating in the thermosphere is the absorption of
highly energetic solar radiation
highly energetic solar radiation