NCERT Solutions for Class 7 Science Chapter 8 - Winds, Storms and Cyclones

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Chapter 8 - Winds, Storms and Cyclones Exercise 92

Solution 1

(a) Wind is moving air.
(b) Winds are generated due to uneven heating on the Earth.
(c) Near the Earth's surface warm air rises up whereas cold air comes down.
(d) Air moves from a region of high air pressure to a region of low air pressure.

Concept insight: List the properties of air.

Solution 2
The following are the two methods to find out the direction of wind:
(i) While flying a kite, air exerts pressure on the kite due to which the kite flies. The direction in which the kite flies is the direction of blowing of wind.
(ii) While riding a bicycle, the direction in which it is difficult to ride is opposite to the direction of the blowing wind.
Therefore, while flying a kite or riding a bicycle, the wind direction at a given place can be determined.
Concept insight: Wind always blows from an area of high air pressure to low air pressure.
Solution 3

We have experienced that when we blow a balloon, the balloon becomes tight. If we try to fill more air, then the balloon bursts after an extent. This happens because air exerts pressure.
We have also experienced the movement of fringes of windows and doors of our house when wind blows in a high speed. This also happens because air exerts pressure.

Concept insight: List the properties of air.

Solution 4

A house having windows but no ventilators should not be bought. This is because warm air is lighter than cold air and therefore, it goes up. This warm air goes outside the house mostly through ventilators. If there are no ventilators, then the warm air cannot move out easily and can cause suffocation.

Concept insight: Ventilators are necessary so that warm and stale air can move out of the room. Otherwise, it will create suffocation.

Solution 5

Air exerts pressure. Wind blowing in high speed may break or displace many things. Holes are made in hanging banners and hoardings so that air can pass through them and reduces the air pressure exerted on the banners and hoardings.

Concept insight: To reduce the air pressure on hoardings and banners holes are made in them.

Solution 6

In case cyclone approaches, we should help our neighbours in the following ways:

(i) By helping them in moving to cyclone shelters and other safe places.

(ii) By asking them to take necessary steps to shift animals, vehicles and household goods to safer places.

(iii) By calling the emergency services such as police, fire brigade and medical centers when required.

(iv) By not pressurising the rescue force by making undue demands.

Concept insight: Important from Exam Point of View.

Solution 7

The following planning is required to deal with the situation created by a cyclone:
(i) Facilities for cyclone prediction and forecasting which can give cyclone warning in advance.
(ii) Quick information and communication linkages so that information can be spread quickly.
(iii) Construction of cyclone shelters and arrangement for moving people to safer places for safety during cyclone.

Concept insight: List the effective safety measures taken by the government in cyclone prone areas.

Solution 8

(iii) Amritsar

Concept insight: The areas which are far away from the sea are unlikely to be affected by cyclones.

Chapter 8 - Winds, Storms and Cyclones Exercise 93

Solution 9
(i) Correct
Concept insight: In winter the winds flow from the land to the ocean. This is called land breeze. Because high pressure is created over land and low pressure on ocean.
(ii) Not Correct
Concept insight: In summer, the winds flow from the ocean towards the land because low air pressure is created on land and air pressure on water is high. This is called sea breeze.
(iii) Not Correct
Concept insight: A cyclone is formed by a very low-pressure system with very high-speed winds revolving around it. The low-pressure region is called the eye of the cyclone.
(iv) Not Correct
Concept insight: The coastline of India is very vulnerable to cyclones.