Class 7 | Science | Chapter- 8 | Winds, Storms and Cyclones Notes

Class 7           Science

Chapter- 8

Winds, Storms and Cyclones Notes

Air- The Invisible gaseous substance surrounding the earth.

Wind- The moving air is called the wind. Air moves from the region where the air pressure is high to the region where the pressure is low.

Air Properties:-

• Air around us exerts pressure.
• Air expands on heating and contracts on cooling.
• Warm air rises up, whereas comparatively cooler air tends to sink toward the earth’s surface.
• As warm air rises, air pressure at that place is reduced and the cooler air moves to that place.

Types of Air- 

• Wind Currents- Wind currents are generate due to uneven heating on earth.

• Thunderstorm- Storm with thunder and lighting along with the rain.

In Thunderstorm winds carry water droplets upwards, where they freeze, and fall down again. The swift movement of the falling water droplets along with the rising air create lightning and sound. It is this event that we call a thunderstorm.

Cyclone- A cyclone is a large scale air mass that rotates around a strong center of low atmospheric pressure. Cyclones are characterized by inward spiraling winds that rotate about a zone of low pressure.

 EFFECTIVE SAFETY MEASURES-

• A cyclone forecast and warning service.
• Rapid communication of warnings to the Government agencies, the ports, fishermen, ships and to the general public

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 places; avoid driving on roads through standing water, as floods may have damaged the roads; and keep ready the phone numbers of all emergency services like police, fire brigade, and medical centres.

Some other precautions, if you are

staying in a cyclone hit area —

●  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 go out just for the sake of fun.

● Do not pressurise the rescue force

by making undue demands.

●  Cooperate and help your neighbours

and friends.

• Winds carrying water vapour bring rain.
• High-speed winds and air pressure difference can cause cyclones.
• It has become easier to monitor cyclones with the help of advance technology like satellites and radars.
• Self-help is the best help. Therefore it is better to plan in advance and be ready with defence against any approaching cyclone.
• The following flow chart will help you to understand the phenomena that lead to the formation of clouds and falling of rain and creation of storms and cyclones: