# MP Board Class 7th Science Solutions Chapter 8 Winds, Storms and Cyclones

## MP Board Class 7th Science Solutions Chapter 8 Winds, Storms and Cyclones

### Winds, Storms and Cyclones Intext Questions

Question 1.
I wonder why the winds shown in the figure are not in the exact north – south direction?

The winds would have flown in the north – south direction from north to south or from south to north. A change in direction from however, caused by the rotation of the earth.

Question 2.
I want to know what these winds do for us?
The winds from the oceans carry water and bring rain. It is a part of the water cycle.

Activities

Activity – 1
Blow the balloons:
Take two balloons of approximately equal size. Put a little water into the balloons. Blow up both the balloons and tie each one to a string. Hang the balloons 8 – 10 cm apart on a cycle spoke or a stick. Blow in the space between the balloons.

Question 1.
What did you expect? What happens?
We expected that balloons would move apart. But the balloons come closer.

Activity – 2
Can you blow and lift?
Hold a strip of paper, 20 cm long and 3 cm wide, between your thumb and forefinger as shown in the paper. Paheli Thinks that the strip will be lifted up. Boojho thinks that the strip will bend down.

Question 1.
What do you think Will happen to the paper?
Paper strip will be lifted up.

Question 2.
Were the observations along the lines you thought?
Yes.

Question 3.
Do you get the feeling that the increased wind speed is accompanied by a reduced air pressure?
Yes.

Activity – 3
Take two paper bags or empty paper cups of the same size. Hang the two bags in the inverted position on the two ends of a metal or wooden stick. Tie a piece of thread in the middle of the stick. Hold the stick by the thread (See Fig.) as in a balance. Put a burning candle below one of the bags as shown in the figure. Observe what happens.

Question 1.
Why is the balance of the bags disturbed?
The bag below which the candle is lighted, is pushed up by the rising hot air from above the candle flame.

Question 2.
Does this activity indicate that warm air rises up?
Yes.

Question 3.
Does the disturbance of the balance suggest that the warm air is lighter than the cold air?
Yes.

350 Degrees F to C, 176.667 °C. The Celsius (ºC) degree or Fahrenheit (ºF) degree temperature scales are used to convert temperature.

### Winds, Storms and Cyclones Text Book Exercises

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

1. Wind is ……………. air.
2. Winds are generated due to ……………. heating on the earth.
3. Near the earth’s surface ……………. air rises up whereas air comes down.
4. Air moves from a region of ……………. pressure to a region of pressure.

1. Moving
2. Uneven
3. Warm, cooler
4. High, low.

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

1. By wind direction indicator.
2. By watching the direction of movement of a paper released in air.

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

1. Compressed air is used in the brake system for stopping trains.
2. Blowing air in a balloon makes it expand.

Question 4.
No, a house which has no ventilators is not a healthy house to live in. Basically ventilators provide a path for warm air to go out of the rooms.

Question 5.
Explain why holes are made in hanging banners and hoardings?
We know that air exerts pressure, so that due to this pressure banners and hoardings flutter when the wind is blowing. The holes are made in the banners and hoardings as wind pass through that holes and they does not become loose and fall down.

Question 6.
I will help by following ways:

1. By warning everyone about the coming danger.
2. Searching for shelter.
3. Moving people fast to safe places.
4. Managing first aid facility.

Question 7.
What planning is required in advance to deal with the situation created by a cyclone?
The following planning is required in advance to deal with the situation created by a cyclone:

1. Listening carefully to warnings being transmitted on TV and radio.
2. Setting up cyclone warning system,
3. Moving to cyclone shelter.
4. Storing food in water – proof bags.
5. Keeping an emergency kit ready.

Question 8.
Which one of the following place is unlikely to be affected by a cyclone.

1. Chennai
2. Mangaluru (Mangalore)
3. Amritsar
4. Puri.

3. Amritsar.

Question 9.
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.

1. In winter the winds flow from the land to the ocean.

Extended Learning – Activities and Projects

Question 1.
You can perform the Activity 8.5 (of textbook) in the chapter slight differently at home. Use two plastic bottles of the same size. Stretch one balloon on the neck of each bottle. Keep one bottle in the sun and the other in the shade. Record your observations. Compare these observations and the result with those of Activity 8.5 of text book
Do yourself.

Question 2.
You can make your own anemometer?
Collect the following items:
4 small paper cups (used ice cream cups), 2 strips of cardboard (20 cm long and 2 cm wide), gum, stapler, a sketch pen and a sharpened pencil with eraser at one end. Take a scale draw crosses on the cardboard strips as shown in the Fig. (a). This will give you the centres of the strips.

Fix the strips at the centre, putting one over the other so that they make a plus (+) sign. Now fix the cups at the ends of the strips. Colour the outer surface of one cup with a marker or a sketch pen. All the 4 cups should face in the same direction.

Push a pin through the centre of the strips and attach the strips and the cups to the eraser of. the pencil. Check that the strips rotate freely when you blow on the cups. Your anemometer is ready. Counting the number of rotations per minute will give you an estimate of the speed of the wind.

To observe the changes in the wind speed, use it at different places and different times of the day. If you do not have a pericil with attached eraser you can use the tip of a ball pen. The only condition is that the strips should rotate freely. Remember that this anemometer will indicate only speed changes. It will not give you the actual wind speed.

Question 3.
Collect articles and photographs from newspapers and magazines about storms and cyclones. Make a story on the basis of what you learnt in this chapter and the matter collected by you?
Do with the help of your subject teacher.

Question 4.
Suppose you are a member of a committee, which is responsible for creating development plan of a coastal state. Prepare a short speech indicating the measures to be taken to reduce the suffering of the people caused by cyclones?
Do with the help of your subject teacher.

Question 5.
Interview eyewitness to collect the actual experience of people affected by a cyclone?
Do with the help of your subject teacher.

Question 6.
Take an aluminium tube about 15 cm long and 1 to 1.5 cm in diameter. Cut slice of a medium – sized potato about 2 cm thick. Insert the tube in the slice, press it, and rotate it 2 – 3 times. Remove the tube. You will find a piece of potato fixed in the tube like a piston head. Repeat the same process with the other end of the tube. Now you have the tube with both ends closed by potato pieces with an air column in between.

Take a pencil with one end unsharpened. Place this end at one of the pieces of potato. Press it suddenly to push the potato piece in the tube. Observe what happens. The activity shows rather dramatically how increased air pressure can push things.
Do yourself.

### Winds, Storms and Cyclones Additional Important Questions

Objective Type Questions

Question 1.
Choose the correct alternative:

Question (i)
A storm is marked by –
(a) Strong winds
(b) Rain
(c) Thunder the lightning
(d) All the above.
(d) All the above.

Question (ii)
The moving air is called –
(a) Wind
(b) Strong winds
(c) Storm
(d) None of these.
(a) Wind

Question (iii)
The amount of water on the earth remains more or less the same because of –
(a) Thunder
(b) Storm
(c) Flood
(d) Water cycle.
(d) Water cycle.

Question (iv)
The word monsoon is derived from –
(a) Arabic word
(b) English word
(c) Hindi word
(d) Urdu word.
(a) Arabic word

Question (v)
The diameter of the eye of the cyclone varies from –
(a) 10 km to 15 km
(b) 10 km to 20 km
(c) 10 km to 30 km
(d) 10 km to 40 km.
(c) 10 km to 30 km

Question (vi)
(a) 200 km/h
(b) 300 km/h
(c) 350 km/h
(d) None of these.
(b) 300 km/h

Question 2.
Fill in the blanks :

1. Orissa was hit by a cyclone with wind speed of 200 km/h on …………….
2. On 29 October, 1999, a second cyclone with wind speed of ……………. hit Orissa again.
3. The greater the difference in pressure, the ……………. the air moves.
4. The worm air is lighter than the ……………. air.
5. At the poles, the air is colder than that at latitudes about ……………. degrees.
6. The word monsoon is derived from the Arabic word …………….
7. Clouds bring ……………..
8. Farmers in our country depend mainly on rains for their …………….
9. A large cyclone is a violently rotating mass of ………… in the atmosphere.
10. A tornado is a ……………. funnel shaped cloud that reaches from the sky to the ground.

1. 18 October 1999
2. 260 km/h
3. Faster
4. Cold,
5. 60
6. Mausam
7. Rain
8. Harvests
9. Air
10. Dark.

Question 3.
Which of the following statements are true (T) or false (F):

1. The cyclone affected agriculture, communication, transport and electricity supply.
2. On heating the air expands and occupies more space
3. In winter, the direction of the wind flow gets reversed.
4. The winds from the oceans carry water arid bring rain.
5. Water cycle is not a continuous phenomenon.
6. Thunderstorms are caused by violent air current inside the cumulus clouds.
7. The cyclones are called hurricane in America.
8. The storms are called typhoons in China.
9. Uneven heating on the earth is the main cause of wind movement.
10. We must stand under a high-rise building or a tree when caught in a thunderstorm.
11. Tropical cyclones occur throughout the year.
12. Lightning, rains and storms are always harmful for the earth.

1. True (T)
2. True (T)
3. True (T)
4. True (T)
5. False (F)
6. True (T)
7. True (T)
8. True (T)
9. True (T)
10. False (F)
11. False (F)
12. False (F)

Question 4.
Match the items in Column A with Column B:

(i) (b)
(ii) (c)
(iii) (d)
(iv) (a).

Winds, Storms and Cyclones Very Short Answer Type Questions

Question 1.
What is a wind?
The moving air is called wind.

Question 2.
Define the term cycle?
A cycle is an event or phenomenon which repeats it selfs after sometime.

Question 3.
Define the term evaporation?
The process of changing water from its liquid form to its vapour is known as evaporation.

Question 4.
When you fly a kite, does the wind coming from your back help?
Yes.

Question 5.
If you are in a boat, is it easier to row it if there is wind coming from behind you?
Yes.

Question 6.
A tornado is a dark funnel shaped cloud that reaches from the sky to the ground. In our country tornadoes are not very frequent.

Question 7.
Which region gets maximum sunlight?
Regions close to the equator get maximum sunlight.

Question 8.
What do you mean by the “eye” of a storm?
The centre of a cyclone is calm area. It is called the eye of the storm.

Question 9.
Can you imagine what would happen if high speed winds blow over the roofs of buildings?
If the roofs were weak, they would be lifted and blown away.

Question 10.
What do you mean by “hurricane”?
“Hurricane” is the term used for storm in West Indies and America.

Question 11.
A cyclone alert or cyclone watch is issued 48 hours in advance of any expected storm.

Question 12.
Which factors contribute to the development of cyclone?
Facters like wind speed, wind direction, humidity and temperature contribute to the development of cyclones.

Question 13.
When is cyclone warning issued?
A cyclone warning is issued 24 hours in advance.

Question 14.
Why smoke always rises up?
Smoke is hotter than air, so it is also lighter than air. That is why smoke always moves up.

Question 5.
How do “high – speed winds” harm us ?
High – speed winds accompanying a cyclone can damage houses, telephones and other communication systems, trees, etc. causing tremendous loss of life and property.

Question 16.
What is “beaufort scale”?
The number and name of a wind is determined by the speed at which it flows on an internationally accepted scale, called beaufort scale.

Question 17.
Is our body a conductor?
Yes.

Question 18.
How are high building protected from lightning?
High buildings are protected from lightning by fixing lightning conductor on the building.

Winds, Storms and Cyclones Short Answer Type Questions

Question 1.
How is storm caused?
When the wind blows gently, it is called a breeze. But, when it blows very fast it cause storm. Storm may be defined as something taking place in the weather of a violent nature. At sea, a storm may be a strong wind or gale. On land, a storm usually means a weather situation marked by heavy rain and often with strong winds, lightning and thunder.

Question 2.
Explain the structure of a tornado?
The diameter of a tornado can be as small as a metre and as large as a kilometer, or even wider. The funnel of a tornado sucks dust, debris and everything near it at the base (due to low pressure) and throws out near the top.

Question 3.
How is lightning useful in nature?
Lightning is useful in nature because during lightning in tense heat and high temperature are produced. As a result, nitrogen combines with oxygen to form its oxides. These oxides of nitrogen further get dissolved in water to form a dilute solution of nitric acid that comes to the ground with rain. This is how nature provides nitrogenous compounds to plants that are important for their growth.

Question 4.
How are lightning and thunder caused?
When two oppositily charged clouds are near each other, the air between them becomes good conductor because charges begin, to move in air very speedily. The presence of electric charges in very large quantities in the air causes to appear as sleaks of lightning and thunder.

Question 5.
Explain the terms thunderstorms and cyclones.
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 waterd roplets along with the rising air create lightning and sound. It is this event that we call a thunderstorm.

Question 6.
Suggest precautios if a storm is accompanied by lightning?
If a storm is accompanied by lightning, we must take the following precautions:

1. 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,
2. Do not take shelter under an umbrella with a metallic end.
3. Do not sit near a window. Open garages, storage sheds, metal sheds are not safe places to take shelter.
4. A car or a bus is a safe place to take shelter.
5. If you are in water, get out and go inside a building.

Question 7.
Suggest some effective safety measures for cyclone.
Some Effective Safety Measures:

1. A cyclone forecast and warning service.
2. Rapid communication of. warnings to the Government agencies, the ports, fishermen, ships and to the general public.
3. Construction of cyclone shelters in the cyclone prone areas, and Administrative arrangements for moving people fast to safer places.

Winds, Storms and Cyclones Long Answer Type Questions

Question 1.
How does a thunderstorm becomes a cyclone?
Before cloud formation, water takes up heat from the atmosphere to change into vapour. When water vapour changes back to liquid form as raindrops, this heat is released to the atmosphere. The heat released to the atmosphere warms the air around. The air tends to rise and causes a drop in pressure. More air rushes to the centre of the storm. This cycle is repeated. The chain of events ends with the formation of a very low – pressure system with very high – speed winds revolving around it. It is this weather condition that we call a cyclone. Factors like wind speed, wind direction, temperature and humidity contribute to the development of cyclones.

Question 2.
Define the structure of a cyclone?
Structure of a cyclone:
The centre of a cyclone is a calm area. It is called the eye of the storm. A large cyclone is a violently rotating mass of air in the atmosphere, 10 to 15 km high. The diameter of the eye varies from 10 to 30 km. It is a region free of clouds and has light winds. Around this calm and clear eye (See Fig.), there is a cloud region of about 150 km in size.

In this region there are high – speed winds (150-250 km/h) and thick clouds with heavy rain. Away from this region the wind speed gradually decreases. The formation of a cyclone is a very complex process.

Question 3.
With a neat diagram show the formation of a cyclone.

Question 4.
Describe the action taken by the people and some precautions if you are staying in a cyclone hit area?
Action on the part of the people:

1. We should not ignore the warnings issued by the meteorological department throught TV, radio, or newspapers.
2. We should make necessary arrangements to shift the essential household goods, domestic animals and vehicles, etc. to safer places.
3. We should avoid driving on roads through standing water, as floods may have damaged the roads.
4. We should keep ready the phone numbers of all emergency sendees like police, fire brigade, and medical centres.

Some precautions, if you are staying in a cyclone hit area:

1. Do not drink water that could be contaminted. Always store drinking water for emergencies.
2. Do not touch wet switches and fallen power lines.
3. Do not go out just for the sake of fun.
4. Do not pressurise the rescue force by making undue demands.