NCERT 7th Class (CBSE) Science: Winds, Storms and Cyclones

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

Answer: 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 can go outside the house mostly through ventilators. If there are no ventilators, then the warm air cannot go outside easily.

Question: Which of the statements given below is correct?

1. In winter the winds flow from the land to the ocean.
2. In summer the winds flow from the land towards the ocean.
3. A cyclone is formed by a very high-pressure system with very high-speed winds revolving around it.
4. The coastline of India is not vulnerable to cyclones.

Answer: 1. Correct – In winter the winds flow from the land to the ocean. This is called land breeze.
2. Not Correct – In summer the winds flow from the ocean towards the land. This is called sea breeze.
3. Not Correct – 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.
4. Not Correct – The coastline of India is very vulnerable to cyclones.

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

Answer: The following planning is required to deal with the situation created by a cyclone.

1. Facilities for cyclone prediction and forecasting which can give cyclone warning in advance.
2. Quick information and communication linkages so that information can be spread quickly.
3. Construction of cyclone shelters and arrangement for moving people to safer places for safety during cyclone.

Question: How will you help your neighbours in case cyclone approaches your village/town?

Answer: In case cyclone approaches, the neighbours should be helped in the following ways:

1. By helping in moving to cyclone shelters and other safer places.
2. By asking them to take necessary steps to shift animals, vehicles and household goods to safer places.
3. By calling the emergency services such as police, fire brigade and medical centres when required.

Question: What is the pressure exerted by air on other objects called?

Answer: The pressure exerted by air is called air pressure. Air exerts pressure in all directions and on all objects. The pressure exerted by air depends on temperature and altitude.

Question: What happens to air when it is heated?

Answer: As the temperature of air increases, its volume also increases, its volume also increases because its particles move apart, that is, air expands on heating.

Question: Name the instrument used to measure the wind speed.

Answer: It is commonly measured using a device called anemometer and expressed in kilometre per hour (km/h).