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1. troposphErE
The first and the most important layer of the atmosphere is made out of the gases that we
breathe everyday. Its average height is 13 km. This layer is called the troposphere. The

troposphere is the layer that we live in and where all weather phenomena like rainfall, fog
and hailstorm take place. This layer contains the air we breathe, the winds are observe and
the clouds that bring out rain. The layer closest to the surface is the troposphere, which
contains over 80 percent of the atmospheric mass and nearly all the water vapour.

2. stratosphErE

This extends to a height of 50 km above the earth’s surface. The temperature is constant
in the lower part of the stratosphere but there is a gradual increase in the upper part.
Stratosphere contains ozone which absorbs the ultraviolet radiation of the sun. Being a
cloud free zone where no weather phenomena takes place, this layer is ideal for jet flying.

3. mEsosphErE
This is the third layer of the atmosphere. It lies above the stratosphere. It extends up to the

height from 50 to 80 km. Meteorites burn up in this layer on entering from the space. This is the
coldest layer in the atmosphere. The temperature reaches to – 100°C at the height of 80 km.

4. thErmosphErE

Lying above the Mesosphere, this layer extends up to a height of more than 400 km. Here,
the temperature rises rapidly with increasing height. This layer contains ‘ions’ which are
electrically charged particles that reflect radio waves back to the earth and enable ‘wireless
communications’. It is also called the ‘ionosphere’ because of the presence of ions.

5. ExosphErE

It is outermost layer of the earth’s atmosphere, where atmospheric pressure and temperature
are low. The upper most layer of the atmosphere is known as exosphere. This layer has very
thin air. Light gases like helium and hydrogen float into the space from here.

siGnifiCanCE of thE atmosphErE

The atmosphere is of great significance for the earth. It acts as a blanket and protects
us from the harmful ultra violet rays of the sun. The carbon dioxide content, apart from
helping the plants to produce food, also helps in keeping the earth warm by absorbing

heat. The presence of oxygen and nitrogen is essential for both animal and plant life. The
water vapour in the atmosphere leads to precipitation and influences weather and climate.

WEathEr and ClimatE

Weather can be defined as the sum total of the current atmospheric conditions like
temperature, humidity, wind and rainfall at any given place. All of these atmospheric
conditions are collectively known as the weather. Therefore, weather can be sunny, windy,
rainy, cloudy or snowy.

Social Studies
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