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L ayers of Atmosphere
The thick envelope of air and gases that surrounds the earth is called its atmosphere.
It can be roughly divided into five concentric layers with each layer having distinct
characteristics.
1. Troposphere: It is the lowest layer of the atmosphere. It ranges from 0-12 km. It
contains 75 per cent of the gaseous mass and nearly all the water vapour. It is the
narrowest and the densest of all the layers. It is a very important layer for human
beings because it is closest to the earth’s surface, and all the weather phenomena
occur in this layer.
2. Stratosphere: This layer lies above the troposphere and extends from about 12-50
kilometres. It is made up of 80 per cent nitrogen and 18 per cent oxygen. It protects
us by absorbing the harmful ultraviolet radiation. This layer is also important
because jet planes fly here owing to the high visibility.
3. Mesosphere: This is the third layer 10, 000 km
that extends above the stratosphere
from 50-80 kilometres. It is the coldest
layer of the atmosphere and it burns up 700 km Exosphere
the meteors that strike the earth from
outer space. Thermosphere
80 km
4. Thermosphere: This is the second
highest layer extending between 80-700 Mesosphere
kilometres. This zone is completely 50 km
devoid of water vapour and the air Stratosphere
pressure is extremely low here. 12 km
Troposphere
5. Exosphere: The highest layer of
the atmosphere extends 700–10,000
kilometres and gradually merges into
outer space. It mainly comprises the
lighter helium and hydrogen gases Layers of Atmosphere
and no meteorological phenomena can
occur in this zone. Most of the satellites Factual Study
that orbit the earth are found here. In the mesosphere, a unique phenomenon,
called the Aurora Borealis (northern lights)
and Aurora Australis(southern lights), can
be seen. It is a spectacular display of light
that can be seen with the naked eye at
midnight near the poles. It is named after
the Roman Goddess of Dawn, Aurora.
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