Question

The hottest region of the atmosphere is:
[A] Mesosphere
[B] Stratosphere
[C] Thermosphere
[D] Troposphere

Answer 1

Hint: The earth’s atmosphere is divided into 4 main parts which are given to us. Here, the correct answer is the layer which is topmost. That layer absorbs the highest amount of solar energy making it the hottest.

Complete step by step answer:
To answer this question, let us discuss about each of these layers one by one-
This layer of gases surrounding earth is known as atmosphere and it consists of mainly 4 more layers depending on their temperatures. We will discuss these layers below-
The Troposphere- It is the lowest part of the atmosphere, the part where we live. It contains most of the natural climatic changes like rainfall, snowfall, clouds. In this part, the temperature change varies day to day. The troposphere contains 75% of all the air in the atmosphere. 0-10 km from the ground is the troposphere.

 The layer above the troposphere is-
The Stratosphere- This extends upward from the tropopause (which is the top most layer of the troposphere) to about 50km. This layer contains most of the ozone gas present in the atmosphere. The increase in temperature with increasing height is due to the absorption of ultraviolet rays by this ozone layer.

Above this layer lies-
The Mesosphere- This layer stretches from 50-80kms from the earth’s surface. Here, the temperature decreases with height, reaching a minimum of -90 degrees.
The Thermosphere- Above the mesosphere, lies the thermosphere which is 80-700kms from the ground. This is also referred to as ionosphere as the energetic solar radiation turns the atoms and molecules in this layer into a positive ion by eliminating an electron. This layer absorbs radio waves, allowing it to receive shortwave radio broadcasts. In this layer, UV rays cause ionization and the temperature increases with altitude here due to absorption of solar radiation, making it the hottest.
We can understand from the above discussion that the thermosphere has the highest level of absorption of high energy solar radiation, making it the hottest.
So, the correct answer is “Option C”.

Note: The other layers present are the Exosphere which is the region above 700kms and the region above 1000km is the Magnetosphere.
The Earth is surrounded by a layer of air which consists of different gases like nitrogen, oxygen, carbon dioxide, noble gases and other gases. Out of these, nitrogen is most abundant. This is known as the atmosphere of the earth.