NCERT Solutions Std 7 Science Winds, Storms and Cyclones

Winds, Storms and Cyclones

Exercise:

1). Fill the missing word in the blank spaces in the following statements:

(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 comparatively cooler air comes down.

(d) Air moves from a region of high air pressure to a region of low air pressure.

2). Suggest two methods to find out wind direction at a given place.

Ans: Two methods to find out the wind direction at a given place are

i). weather wane

ii). holding the dust and releasing in the air.

3). State two experiences that made you think that air exerts pressure (other than those given in the text).

Ans: Balloon bursts when filled with more amount of air and banners hanging in open places torn out due to fast moving air.

4). You want to buy a house. Would you like to buy a house having windows but no ventilators? Explain your answer.

Ans: Warm air rises upwards and cool air comes downward. So to make a continuous of flow of fresh air inside the house there must be ventillators in the upper parts of the walls.

5). Explain why holes are made in hanging banners and hoardings.

Ans: Air exerts pressure. If there are no holes in the hanging banners and hoardings they will be damaged. To make them safe the holes are made in hanging banners and hoardings.

6). How will you help your neighbours in case a cyclone approaches your village/town?

Ans: We will help our neighbours by

 i). making necessary arrangements to shift the essential household goods, domestic animals and vehicles, etc. to safer places;

ii). asking them to avoid driving on roads through standing water, as floods may have damaged the roads.

iii). keeping ready the phone numbers of all emergency services like police, fire brigade, and medical centres.

iv). asking thme not to drink water that could be contaminated.

v). asking them not to touch wet switches and fallen power lines.

vi) asking them not to go out just for the sake of fun.

7). What planning is required in advance to deal with the situation created by a cyclone?

Ans: Planning required in advance to deal with the situation created by a cyclone are

i). A cyclone forecast and warning service.

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

iii). Construction of cyclone shelters in the cyclone prone areas

iv). Administrative arrangements for moving people fast to safer places.

8). Which one of the following places is unlikely to be affected by a cyclone?

(i) Chennai                                (ii) Mangaluru (Mangalore)

(iii) Amritsar                             (iv) Puri

Ans: (iii) Amritsar    

9). 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.

Answer: (i) In winter the winds flow from the land to the ocean.

Additional Questions:

Fill in the blanks.

i). Air exerts pressure.

ii). The warm air is lighter than the cold air.

iii). On heating the air expands and occupies more space.

iv). The word monsoon is derived from the Arabic word Mausam

Write whether True or False.

 i). Air exerts pressure.

Ans: True

ii). The greater the difference in pressure, the faster the air moves.

Ans: True.

iii). The cold air is lighter than the warm air.

Ans: False

iv). Increased wind speed is, indeed, accompanied by reduced air pressure.

Ans: True

v). The greater the difference in pressure, the faster the air moves.

Ans: True.

Answer the following.

1). What was the speed of the Orissa Cyclone in 1999?

  Ans: 200 km/h.

2). What is wind?

Ans: The moving air is called wind.

3). Mention the precautions to be taken during a storm 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.

4). Write a note on a thunderstorm.

Ans: Thunderstorms develop in hot, humid tropical areas like India very frequently. The rising temperatures produce strong upward rising winds. These 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 creates lightning and sound. It is this event that we call a thunderstorm.

5). What is a cyclone?

  Ans: A cyclone is a very low-pressure system with very high-speed winds revolving around it.  

6). What are the other names of cyclones?

Ans: The other names of cyclones are hurricanes in America and typhoons in Japan.

Click here for the solutions of

1). Nutrition in Plants

2). Nutrition in Animals

3). Fibre to Fabric

4). Heat

5). Acids, Bases and Salts

6). Physical and Chemical Changes

7). Weather, Climate and Adaptations of Animals to Climate

8). Winds, Storms and Cyclones

9). Soil

10). Respiration in Organisms

11). Transportation in Animals and Plants

12). Reproduction in Plants

13). Motion and Time

14). Electric Currents and its Effects

15). Light

16). Water: A Precious Resource

17). Forests: Our Lifeline

18). Wastewater Story

 

 

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