Chapter 8 Winds, Storms and Cyclones

Moving air is called wind.
Pressure may be defined as the force that a gas or liquid exert when contained inside something.
Air exert pressure.
As the pressure of air is low, the wind speed is increased whereas if the air pressure is higher than the wind speed decreases.
Air moves from the region where the pressure of air is high to the region
Air expands in size and occupies more space on heating.
The region closer to the equator get maximum heat from run.
Wind blow from the North and the South towards the land.
A thunderstorm is arises from the heavy rainfall along with the rising air create lightening and sound.
A condition of weather in which high speed wind revolving around a low pressure is called cyclone.
The center part of a cyclone is called as the eye of the cyclone.
A device which is used to measure the speed of wind is called anemometer.
The flash of light in the sky that is produced by electricity moving between clouds or from clouds to the ground.
Hurricane is a tropical cyclone with winds of 75 miles or greatly that is usually accompanied by rain, thunder and by lightening.
A violent storm with a column of rapidly rotating winds having the appearance of dark funnel shaped clouds that reaches from the sky to the ground is called as Tornado.
A type of storm system having circular and spiral violent winds called as Typhoon. It eventually occur in western Pacific Ocean.

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Exercise 1 ( Page No. : 93 )

Q1	Fill the missing word in the blank spaces in the following statements: (a) Wind is——————air. (b) Winds are generated due to —————— heating on the earth. (c) Near the earth’s surface __________air rises up whereas ___________ air comes down. (d) Air moves from a region of ——— pressure to a region of ———.
Ans:	(a) Moving Wind is moving air. It is produced by the uneven heating of the earth’s surface by the sun. Since the earth’s surface is made of various land and water formations, it absorbs the sun’s radiation unevenly. (b) Uneven Winds are generate due to uneven heating on the earth. Winds energy is created by the uneven heating of the Earth’s surface by the Sun. During the day, the air above the land heats faster than air over water. This warm air over the land expands and rises, and the cooler air, which is heavier takes its place, creating wind. (c) Hot, cold It is so because warm air is light in weight. So, it rises up whereas cool air comes down. (d) High, low Air moves from a region of high pressure to a region of low pressure. The movement of air caused by temperature or pressure differences in wind. Where there are differences of pressure between two places, a pressure gradient exists, across which air moves from the high pressure region to the low pressure region.

Q2	Suggest two methods to find out wind direction at a given place.
Ans:	Methods to find the direction of wind are following: (a) Take a handful of sand or dust. Leave the sand from a height and observe the direction in which sand is moving which will show the direction of wind. (b) While flying a kite, the direction in which the kite flies shall be the wind direction. (c) Lift a piece of paper in the air. Now observe the direction of the flying paper, the direction will be the accurate direction of wind.

Q3	State two experiences that made you think that air exerts pressure (other than those given in the text).
Ans:	Air exerts pressure on the wall of the container, this can be seen as follows: Putting air in a balloon make it larger in size. Moving air also move the curtains on the doors and windows. Moving air helps in the flying kites.

Q4	You want to buy a house. Would you like to buy a house having windows but no ventilators? Explain your answer.
Ans:	No, i would not like to buy a house having windows but no ventilators because ventilation provides a path for cool air to come in and warm air to go out of the room. A house without ventilators will not be cool as compared with the ventilator ones. ventilation is must in the house for the air circulation.

Q5	Explain why holes are made in hanging banners and hoardings.
Ans:	Holes are made in hanging banner and hoardings, so the blowing air can pass through them easily. Thus the banner and the hoardings with stand less pressure.

Q6	How will you help your neighbours in case cyclone approaches your village/town?
Ans:	In case of a cyclone approaches, i will help the neighbours in following base: By alerting them about the coming cyclone. By telling them to keep the storage of water and food. By telling them to reach to the safest place as soon as possible. Helping them searching for a safe shelter. I will help them in shifting their cattles and vehicles to the safe place.

Q7	What planning is required in advance to deal with the situation created by a cyclone?
Ans:	Following planning is required in advance to deal with the situation created by a cyclone: Setting up for a cyclone warning system. Setting up for the first aid facility. Setting up for the cyclone safe shelter. Setting up for the storage of food and water.

Q8	Which one of the following place is unlikely to be affected by a cyclone. (i) Chennai (ii) Mangaluru (Mangalore) (iii) Amritsar (iv) Puri
Ans:	(iii) Amritsar In India the cyclones generally affect the coastal areas. Cyclones need large bodies of moderately warm water for their formation. Among the mentioned places, only Amritsar is located far away from the coastal area, all the other places namely Chennai, Mangalore and Puri are located near the sea. So, from the Chennai, Mangalore, Amritsar and Puri; only Amritsar is the one who did not affected by a cyclone.

Q9	Which of the statements given below is correct? (i) In winter the winds flow from the land to the ocean. (ii) In summer the winds flow from the land towards the ocean. (iii) A cyclone is formed by a very high-pressure system with very high-speed winds revolving around it. (iv) The coastline of India is not vulnerable to cyclones.
Ans:	(i) In winter the winds flow from the land to the ocean. During winter the direction of wind is towards the ocean from the land. The water in ocean cools down later as compared to the land; land cools down faster than the ocean water. So, the temperature of water in oceans is higher than that of land. The direction of wind moves from the high pressure area to the low pressure area. Hence, the wind blows from ocean to the land.

Chapter 8 Winds, Storms and Cyclones

Exercise 1 ( Page No. : 93 )

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