Class 7 Science Winds Storms and Cyclones Notes

2.6 Structure of Cyclone

The centre of a cyclone is a calm area. It is called the eye of the storm. A large cyclone is a violently rotating mass of air in the atmosphere, 10 to 15 km high. The diameter of the eye varies from 10 to 30 km.

A cyclone is known by different names in different parts of the world. It is called a ‘hurricane’ in the American continent. In Philippines and Japan it is called a ‘typhoon’.

2.7 Destruction Caused by Cyclones

Some of the harmful effects of cyclones are as follows:

i) Sea water entered in low coastal areas can damage human and animal life and property.

ii) Cyclones can reduce the fertility of soil.

iii) Frequent rains caused by cyclones can result in floods.

iv) High speed winds caused by cyclones can damage houses, telephone lines and other communication systems.

2.8 Tornadoes

A tornado is a dark funnel shaped cloud that reaches from the sky to the ground. Most of the tornadoes are weak. A violent tornado can travel at a speed of about 300 km/h. Tornadoes may form within cyclones.

2.9 Effective Safety Measures

Some of the safety measures in case of cyclones are as follows:

• A cyclone forecast and warning service.

• Rapid communication of warnings to the Government agencies, the ports, fishermen, ships and to the general public.

• Construction of cyclone shelters in the cyclone prone areas, and Administrative arrangements for moving people fast to safer places.

Action on the part of the people

• We should not ignore the warnings issued by the meteorological department through TV, radio, or newspapers.

• We should make necessary arrangements to shift the essential household goods, domestic animals and vehicles, etc., to safer place.

• We should keep ready the phone numbers of all emergency services like police, fire brigade, and medical centres.

• Do not drink water that could be contaminated. Always store drinking water for emergencies.

• Do not touch wet switches and fallen power lines.

• Do not pressurise the rescue force by making undue demands.

• Cooperate and help your neighbours and friends.