Question

The thermosphere begins at a height of _____________
A. 80 km
B. 95 km
C. 105 km
D. 120 km

Answer 1

Hint: From the surface the fourth layer of the atmosphere is called the thermosphere. The thermosphere exists between the mesosphere and the exosphere.

Complete answer: The thermosphere begins at the height of 80 km and continues till 120 km. Broadly there are five layers of the atmosphere - Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere. Thermosphere is derived from the greek word ‘thermo’. The greek word ‘thermo’ means heat.
The temperature of the thermosphere increases by several hundred degrees. This happens because there is constant ionization happening in the thermosphere. Ionization occurs because of the ultraviolet rays of the sun along with gamma rays and X rays of the sun.Thermosphere is the layer disintegration of meteorites occurs as soon as they come in contact with the air. The boundary between it and the exosphere is known as the thermopause. It is estimated that around 99 percent of the earth’s atmosphere is below the thermosphere even though the thermosphere is so huge in size.
Thermospheric storms are produced in the thermosphere whenever large magnetospheric storms occur. The temperature of the thermosphere changes with solar activity. As the thermosphere is filled with ions it is also known as the ionosphere. Radio waves are reflected in the ionosphere.

Therefore the correct answer is option A.

Note: It is estimated that the temperature in the thermosphere can go upto 2000 degree celsius but it cannot be said for sure. Reading temperature, in the thermosphere, is very difficult for the scientist because the air is very thin in the thermosphere.