Page 79 - Innovator's Science-8

• As the warm and moist air (containing a lot of water vapour) rise high
up in the atmosphere, it gets cooled and the water vapour present in

it condenses to form cloud called thunder clouds when water vapour
condenses, it releases heat.
• The heat released by the condensation of water vapour in the

atmosphere warms the air all around. This warm air rises higher into
the atmosphere causing a low pressure. More air rushed to the
centre of the storm. This cycle is repeated.

• The chain of events ends with the formation of a very low pressure
system with very high-speed winds revolving around it. The weather
condition consisting of a system of high speed winds revolving around

a central area of very low pressure to the centre of the cyclone is
called its eye.

• Once a cyclone is formed,
it begins to move over the Northern Hemisphere Southern Hemisphere
surface of ocean. The
Science speed of wind in the
Bytes

Testimony cyclone is more than 120
km. A cyclone needs a
The calm region at the
centre of a cyclone is constant supply of warm
called the eye. It may be and moist air. When air
20-40 km wide, with clear gradually stops, the
skies and light winds,
even while violent winds cyclone dies down.
rage all around it.
In the Southern hemisphere, these tropical storms are called cyclones
and rotate in a clockwise direction.
In the northern hemisphere, cyclones are called hurricanes or typhoons

and rotate in an anti clockwise direction.
India has a large coastline which makes it vulnerable to cyclones both in
terms of intensity and frequency of the cyclones.

Destruction caused by Cyclones
• Water in the water bodies gets pushed towards the shore, which is
indicative of an approaching cyclone. This surge of water can wash

away every thing on the shore leading to loss of life.
• The low pressure in the centre of the cyclone, also collect at the eye

of the cyclone, can lift the water in the seas high as the cyclone
moves towards the shore. This results in sea water entering, the low-
lying areas near the coast and causing damage to life and property.

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