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

Q1: Fill the missing word in the blank spaces in the following statements:
(a) Wind is _________ air.

Ans: Moving

• Wind is the movement of air caused by differences in atmospheric pressure. It plays a crucial role in weather patterns and helps regulate Earth's temperature.

(b) Winds are generated due to _________ heating on the earth.

Ans: Uneven

• Wind is generated by uneven heating of the Earth's surface due to the Sun's energy. This uneven heating occurs because the Earth is a sphere, causing different amounts of sunlight to reach different parts of the Earth's surface. 

(c) Near the earth’s surface _________air rises up whereas _________ air comes down.

Warm, cold

• Warm air rises and cold air sinks due to a phenomenon called convection, which is caused by differences in air density and buoyancy.

(d) Air moves from a region of _________ pressure to a region of _________ pressure.

High, Low

• Air moves from high pressure to low pressure due to differences in air pressure and the principle of equilibrium.

Q2: Suggest two methods to find out wind direction at a given place.

Ans: Two methods to find the direction of wind:
(a) Take a handful of sand or dust. Release it slowly from a height and observe the direction in which the falling sand is moving. This will show the direction of wind.
(b) Tie a thin plastic sheet or cloth with a stick. Keep the stick at a place which is as high as possible. The direction in which the cloth sways shows the direction of wind.

Q3: State two experiences that made you think that air exerts pressure (other than those given in the text).

Ans: I have seen paratroopers jumping from aeroplanes. The parachute helps them in reaching the ground safely. The air pressure reduces the speed of the parachute and the paratrooper lands without getting injured.

Q4: You want to buy a house. Would you like to buy a house having windows but no ventilators? Explain your answer.

Ans: A house should have ventilators along with windows. The warm air would rise up and exit from the ventilators. The cooler air would rush in through the windows. This will help in making the rooms comfortable. A room without ventilators shall not be cooled as efficiently as one with ventilators.

Q5: Explain why holes are made in hanging banners and hoardings.

Ans: Holes are made in hanging banners and hoardings to allow air to pass through them. When these banners and hoardings are hung up outdoors, they can be subjected to strong winds. Without holes, the wind would exert a lot of force on the surface of the banner, which could cause it to tear or get damaged.

By creating holes in the banners and hoardings, the wind can pass through them, reducing the overall force exerted on the surface. This helps prevent the banners from getting blown away or damaged. The holes also help to reduce the pressure buildup behind the banner, preventing it from acting like a sail and creating excessive force.

Q6: How will you help your neighbours in case cyclone approaches your village or town?

Ans: I will take following steps to help my neighbours in case of cyclone:

• Spreading awareness: Inform neighbors about the approaching cyclone and necessary precautions.
• Providing assistance: Help elderly, disabled, or those in need with preparations or evacuation.
• Sharing resources: Coordinate with neighbors to pool essential supplies.
• Offering shelter: Open home or safe space to neighbors without secure accommodations.
• After the cyclone: Assist in cleanup and restoration efforts.
• Emotional support: Be there for neighbors, offering comfort and listening ear.

Q7: What planning is required in advance to deal with the situation created by a cyclone?

Ans: Following planning is required to deal with the situation created by a cyclone:
(i) Proper shelters should be built by the government agencies so that people can be accommodated in them.
(ii) Alternate arrangements of seamless communication among rescue agencies should be made.
(iii) Proper stock of emergency medicines should be kept.
(iv) Proper arrangements of safe drinking water should be made.
(v) Government should chalk out a rehabilitation plan for those affected by cyclone.

Q8: Which one of the following place is unlikely to be affected by a cyclone.
(i) Chennai 
(ii) Mangaluru (Mangalore) 
(iii) Amritsar 
(iv) Puri

Correct Anseer is option (iii)
Amritsar is unlikely to be affected by a cyclone because of its geographical location. Amritsar is located in the northwestern part of India, far away from the coastlines, where cyclones usually originate and affect. Cyclones are formed over warm ocean waters and tend to lose their intensity as they move inland.

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.

Correct Answer is option (i)
In winter, the winds flow from the land to the ocean due to the difference in temperature and pressure between the land and the ocean. During winter, the land gets cooler faster than the ocean. The air above the land becomes cooler and denser, leading to an increase in pressure. On the other hand, the ocean retains heat for a longer time, so the air above the ocean remains warmer and less dense, resulting in lower pressure.