Thermosphere

The thermosphere is the fourth layer of the Earth's atmosphere. It is directly above the mesosphere (middle layer) and directly below the exosphere (top layer).

The name thermosphere is taken from the Greek word "thermos" which means 'heat'. This layer has high temperatures because it absorbs X-rays and extreme ultraviolet radiation from the Sun. Even though it has temperatures of 2,000 °C (3,360 °F), the density of the thermosphere is so low that it doesn't feel hot. The absorbed ionizing radiation also creates the ionosphere. Shortwave radio waves can bounce off the Kennelly-Heaviside layer (ionosphere) and go to distant parts of the Earth. This layer is very helpful in radio communication.

Thermosphere Media

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  A diagram of the layers of Earth's atmosphere

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  Figure 1. Nomenclature of atmospheric regions based on the profiles of electric conductivity (left), temperature (middle), and electron number density in m−3(right)

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  Figure 2. Schematic meridian-height cross-section of circulation of (a) symmetric wind component (P20), (b) of antisymmetric wind component (P10), and (d) of symmetric diurnal wind component (P11) at 3 h and 15 h local time. Upper right panel (c) shows the horizontal wind vectors of the diurnal component in the northern hemisphere depending on local time.