Topic outline

    • Winds, Storms and Cyclones

      Q42. Write a note on wind flow pattern.

      Ans. Regions close to the equator get maximum heat from the Sun. The air in these regions gets warm. The warm air rises, and the cooler air from the regions in the 0–30 degrees latitude belt on either side of the equator moves in. These winds blow from the north and the south towards the equator. At the poles, the air is colder than that at latitudes about 60 degrees. The warm air at these latitudes rises up and the cold wind from the polar regions rushes in, to take its place. In this way, wind circulation is set up from the poles to the warmer latitudes.


      Q43. How a thunderstorm becomes a cyclone?

      Ans. Before cloud formation, water takes up heat from the atmosphere to change into vapour. When water vapour changes back to liquid form as raindrops, this heat is released to the atmosphere. The heat released to the atmosphere warms the air around. The air tends to rise and causes a drop in pressure. More air rushes 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. It is this weather condition that we call a cyclone.

      Q44. List some action on the part of people in case of cyclone.

      Ans. Action on the part of people in case of cyclone

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

                               ii.        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.


      Q45. What precautions would you take, if you are staying in a cyclone hit area?

      Ans. Some precautions, if we are staying in a cyclone hit area —

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

                               ii.        Do not touch wet switches and fallen power lines.

                              iii.        Do not go out just for the sake of fun.

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

                              v.        Cooperate and help your neighbours and friends.


      Q46. What precautions should we take if a storm is accompanied by lightning?

      Ans. If a storm is accompanied by lightning, we must take the following precautions:

                                i.        Do not take shelter under an isolated tree. If you are in a forest take shelter under a small tree. Do not lie on the ground.

                               ii.        Do not take shelter under an umbrella with a metallic end.

                              iii.        Do not sit near a window. Open garages, storage sheds, metal sheds are not safe places to take shelter.

                              iv.        A car or a bus is a safe place to take shelter.

                               v.        If you are in water, get out and go inside a building.

      Q47. Write an experiment to show that air exerts pressure.

      Ans. Take a tin can with a lid. Fill it approximately half with water. Heat the can on a candle flame till the water boils. Let the water boil for a few minutes. Blow out the candle. Immediately put the lid tightly on the can. Put the can carefully in a shallow metallic vessel or a washbasin. Pour fresh water over the can. As water is poured over the can, some steam in the can condenses into water, reducing the amount of air inside. The pressure of air inside the can decreases than the pressure exerted by the air from outside the can. As a result the can gets compressed.

       Image from NCERT

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