The characteristics and the importance of the thermosphere layer
The thermosphere layer
The thermosphere layer is called the thermal layer as it is the hottest layer of the atmospheric envelope. It is the fourth layer of the atmospheric envelope, The temperature of the thermosphere layer increases with a high rate as we go up until it reaches 1200° Celsius.
The thermosphere layer extends from the mesopause (at a height of 85 km above the sea level) to a height of 675 km above the sea level, Its thickness is 590 kilometres.
The upper part of the thermosphere layer contains charged ions and the pressure of these ions extends up to 700 km above the sea level, So this part is called ionosphere.
The thermosphere layer is the layer of the Earth’s atmosphere directly above the mesosphere and below the exosphere, within this layer of the atmosphere, ultraviolet radiation causes the photoionization/photodissociation of molecules, creating ions in the ionosphere.
The thermosphere layer begins at about 85 km above sea level, At these high altitudes, the residual atmospheric gases sort into strata according to molecular mass, Thermospheric temperatures increase with altitude due to the absorption of highly energetic solar radiation.
Temperatures are highly dependent on solar activity and can rise to 1,700 °C or more, Radiation causes the atmosphere particles in this layer to become electrically charged (see ionosphere), that enables radio waves to be refracted and thus be received beyond the horizon.
Dynamics of the thermosphere are dominated by the atmospheric tides, which are driven by the very significant diurnal heating, The Atmospheric waves dissipate above this level because of collisions between the neutral gas and the ionospheric plasma.
The thermosphere layer contains an appreciable concentration of elemental sodium located in a 10-km thick band that occurs at the edge of the mesosphere, 80 to 100 km above Earth’s surface.
The ionosphere layer
The ionosphere layer is a layer that contains the charged ions, and it has an important role in the wireless communications and broadcasting as it reflects the radio waves that transmitted by the radio stations and the communication centres.
The ionosphere layer surrounded by two magnetic belts which are known as Van- Allen belts. These belts play an important role in the scattering of the harmful charged cosmic radiations away from the Earth. This scattering causes the occurrence of Aurora phenomenon, Van- Allen belts are called by this name related to the scientist Van-Allen who discovered them.
The Aurora phenomenon appears as brightly coloured light curtains seen from both poles (the North and the South Poles) of the Earth.
The atmospheric envelope is inserted with the outer space in a region known as Exosphere, in which the satellites orbit around the Earth with the cameras and the telescope, The satellites are used to transmit the weather condition information and TV programs.