Our earth is surrounded by a huge envelope of
air called the atmosphere. Atmosphere
extends to more than 800km above the surface of earth and is held in place by
the earth’s gravity. The atmosphere protects us from many harmful rays coming
from the sun. The air envelope is thicker near the earth’s surface and as we go
higher the density and the availability of air gradually decreases. This is
because, as we go higher, the force of gravity decreases, so it is not able to
hold large amount of air.
The atmosphere is
made of five different layers – the troposphere, the stratosphere,
the mesosphere, the ionosphere and the exosphere.
The troposphere is
the layer closest to the earth. It is the layer in which we live. It extends
upwards for about 16km above the surface of the earth. Movement of wind takes
place in this layer. It also contains water vapour, which is responsible for
making clouds. This layer is responsible for the weather we experience on earth.
Aircrafts usually fly above this layer to avoid
strong winds and bad weather.
lies above the troposphere. This layer has the ozone layer in it. The ozone
layer protects all life on earth from the harmful ultraviolet rays of the sun.
weathercock shows the direction in which the air is moving at a particular
place. You can also make a wind sock to find the direction of the wind. Can you
try it yourself?
USE OF AIR