HBSE 7th Class Science Solutions Chapter 8 Winds, Storms and Cyclones

Haryana State Board HBSE 7th Class Science Solutions Chapter 8 Winds, Storms and Cyclones Textbook Exercise Questions and Answers.

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

HBSE 7th Class Science Winds, Storms and Cyclones Textbook Questions and Answers

Question 1.
Fill the missing word in the blank spaces in the following statements:
(a) Wind is …………… air.
(b) Winds are generated due to …………… heating on the earth.
(c) Near the earth’s surface air rises up whereas …………… air comes down.
(d) Air moves from a region of …………… pressure to a region of …………… pressure.
Answer:
(a) moving
(b) uneven
(c) warm, cooler
(d) high, low.

Question 2.
Suggest two methods to find out wind direction at a given place.
Answer:
(i) Take a piece of a paper in your hand. Let it fall from your hand. It will blow in the direction in which wind is blowing.
(ii) You can use a wind vane (a device helps us to make accurate measurements of wind direction) to find out the direction of wind.

Question 3.
State two experiences that made you think that air exerts pressure (other than those given in the text).
Answer:
(i) Balloons and balls can be used only when they are inflated with air.
(ii) Compressed air is used in the brake system for stopping trains.

Question 4.
You want to buy a house. Would you like to buy a house having windows but no ventilators? Explain your answer.
Answer:
No. A house which has no ventilators is not a healthy house to live in. The air circulation is not there in such a house and hence it has no fresh air.

Question 5.
Explain why holes are made in hanging banners and hoardings.
Answer:
Air exerts pressure. It is due to this pressure banners and hoardings flutter when the wind is blowing. 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.
How will you help your neighbours in case cyclone approaches your village/town?
Answer:
(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, and Administrative arrangements for moving people fast to safer places.

Question 7.
What planning is required in advance to deal with the situation created by a cylone?
Answer:
In order to deal with cyclone, it is important to follow the following points:
(i) listening carefully to warnings being transmitted on TV and radio.
(ii) moving to safer places or taking adequate steps to ensure safety at home.
(iii) keeping an emergency kit ready.
(iv) storing food in water-proof bags.
(v) not venturing into sea.
(vi) keeping all the emergency numbers handy.

Question 8.
Which one of the following place is unlikely to be affected by a cyclone?
(i) Chennai
(ii) Mangalore
(iii) Amritsar
(iv) Puri
Answer:
(iv) Puri.

Question 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.

Extended Learning – Activities And Projects

Question 1.
You can perform the Activity 8.5. in the chapter at home 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.
Answer:
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 (20cm long and 2cm 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. 8.4. This will give you the centres of the strips.

Finding centre of the strips

A model of an anemometer
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 center 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 pencil 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.
Answer:
Do yourself.

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.
Answer:
Do yourself.

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.
Answer:
Do yourself.

Question 5.
Interview eyewitness to collect the actual experience of people affected by a cyclone.
Answer:
Do yourself.

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.
Caution: When you perform this activity, make sure that nobody is standing in front of i e tube.
Answer:
Do yourself.

HBSE 7th Class Science Winds, Storms and Cyclones Important Questions and Answers

Very Short Answer Type Questions

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

Question 2.
Define the term ‘cycle’.
Answer:
It is an event or phenomenon which repeats itself after sometime.

Question 3.
Define term ‘evaporation’.
Answer:
The process of changing water from its liquid form to its vapour is known as evaporation.

Question 4.
Is evaporation a slow process or fast process?
Answer:
Evaporation is a slow process.

Question 5.
Name two processes through which water vapour add continuously into the air.
Answer:
The two processes are:
(i) Evaporation
(ii) Condensation.

Question 6.
Define condensation.
Answer:
The process of conversion of water vapours into liquid form of water is called condensation.

Question 7.
Define water cycle.
Answer:
The water in its vapour form goes into air by evaporation and transpiration forms cloud and, then comes back to the surface of the earth through the process of condensation and precipitation. This process is called ‘water cycle’.

Question 8.
At what speed wind becomes (i) gentle breeze, (ii) storm?
Answer:
When the wind blows gently, it is called a breeze. But, when it blows very fast it causes storm.

Question 9.
What is sea breeze?
Answer:
In coastal areas, during the day, the cool air blows from sea towards the land called sea breeze.

Question 10.
What is land breeze?
Answer:
In coastal areas, during the night, the cool air blows from land to sea called the land breeze.

Question 11.
What is tornadoes?
Answer:
In our country tornadoes are not very frequent. A tornado is a dark funnel shaped cloud that reaches from the sky to the ground.

Question 12.
What is ‘hurricane’?
Answer:
The ‘hurricane’ is the term used for storm in America and West Indies.

Question 13.
What is the eye of hurricane?
Answer:
The region of chimney like low pressure around which warm water vapour spirals is called the eye of hurricane.

Question 14.
What is Beaufort Scale?
Answer:
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 15.
Name two properties of air.
Answer:
(i) Air occupies space
(ii) It has mass.

Question 16.
Write two importances of air in agriculture.
Answer:
(i) Air helps rotate wind-mill which is used to draw water from tube-wells.
(ii) Air helps in dispersion of seeds and pollen grains of flowers of several plants.

Question 17.
How are high building protected from lightning?
Answer:
High buildings are protected from lightning by fixing lightning conductor on the building.

Question 18.
What is the cause of atmospheric electricity?
Answer:
Atmospheric electricity is due to ionisation of air by the ultraviolet rays of sunlight.

Question 19.
Is our body a conductor?
Answer:
Yes, our body is a good conductor of electricity.

Question 20.
What damage can lightning do?
Answer:
Lightning damage the high buildings and the trees on which it strikes. The buildings and trees can be set on fire by lightning. It can do a high loss of life and property.

Question 21.
Why do chimneys made of steel not require lightning conductor?
Answer:
Steel is a good conductor of electricity. Due to this reason steel chimneys do not require lightning conductor. They themselves pass the discharge to the earth.

Question 22.
Why is it advised not to take shelter under a tree during lightning?
Answer:
We should not stand under a tree during lightning, due to the danger of the lightening, because it can destroy the trees and can set it on fire.

Question 23.
Which gas is produced in air during lightning that absorbs ultraviolet radiation present in sunlight?
Answer:
During lightning ozone (oz) gas is produced due to higher temperature which absorbs ultraviolet radiation. It is dangerous for the living being.

Question 24.
Name the arrangement used for the protection of buildings against damage from lightning.
Answer:
To protect buildings from damage by lightning, a good lightning conductor is used. This is done by installing a lightning conductor on the buildings.

Short Answer Type Questions

Question 1.
How is rain caused?
Answer:
Water, on land, is present in different sources, e.g., sea, river, pond, lake, etc. The water from all these sources change into vapour form due to sun’s heat and goes up into the air. This change of water into vapour form is called evaporation. The water vapour, when reaches high up in the air, cools down and forms clouds. This cooling down of water vapour to form clouds is called condensation. On cooling, the water vapour changes to water droplets. These group together farm clouds. When the droplets become very heavy they fall down as rain.

Question 2.
What is water cycle? What does it indicate?
Answer:
Evaporation of water from oceans, ponds, rivers, lakes and from roads and streets to form cloud by condensation at higher altitude. When clouds rain, the rain water flows into the seas and oceans through rivers and streams. Some water percolates into the soil to form underground water. It comes again out in the form of spring and well. This is called water cycle.

Because of water cycle, the amount of water on the earth remains more or less the same. The water cycle also indicates that all the water in world is on the move all the time.

Question 3.
How does water cycle help in maintaining global climate?
Answer:
Water cycle plays an important role in the world climate. Oceans absorb vast quantities of heat and help in global warming. By absorbing heat water evaporates and on condensation releases heat. This absorption and releasing of heat in the form of energy drives weather pattern in the short term and regulate the climate for long time.

Question 4.
How is storm caused?
Answer:
When the wind blows gently, it is called a breeze. But, when it blows very fast it causes 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 5.
How a thunderstorm becomes a cyclone?
Answer:
Water requires heat when it changes from liquid to vapour state. 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.

Question 6.
How is lightning useful in nature?
Answer:
Lightning is useful in nature because during lightning intense 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 7.
How is ozone layer useful for us?
Answer:
During lightning, a part of oxygen gets converted to ozone. Ozone provides protection against harmful ultraviolet radiations of the sun that cannot reach the earth’s surface.

Question 8.
What are the precautions to be taken against a storm is accompanied by lighting?
Answer:
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) It you are in water, get out and go inside a building.

Question 9.
Why is it advisable to switch off TV sets during lightning?
Answer:
Lightning in the sky also effects radio and TV transmission in our radio and TV sets during lightning and thunder is due to this reason. TV antina and dish antina has fixed on tall buildings are especially prove to lightning strikes. So it is advisable to stop our TV set during lightning to save them from damage.

Question 10.
What is a lightning conductor? Why is it fixed on the top of high tall buildings?
Answer:
A lightning conductor is a long flat thick strips of copper with sharp point or spikes. The lower end of it is connected to copper plate deep into the earth. It is fixed on the top of the building because the thundering electricity comes in the contact first and the building will not be damaged.

Question 11.
How are lightning and thunder caused?
Answer:
When two oppositively 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 steaks of lightning and thunder.

Question 12.
When do we say that lightning has struck on the earth?
Answer:
Sometimes the direction of the wind changes; then the clouds move and the charges in the clouds are discharged into the earth when it happens, then it is said that lightning has struck on the earth.

Question 13.
Why should we not stand under a tree during a thunderstorm?
Answer:
We should not stand under a tree during a thunderstorm due to the danger of the lightning because it can destroy the tree, and can set it on fire.

Question 14.
What are tornadoes?
Answer:
In our country tornadoes are not very frequent. A tornado is a dark funnel shaped cloud that reaches from the sky to the ground. Most of the tornadoes are weak. A violent tornado can travel at speeds of about 300 km/h. Tornadoes may form within cyclones.

Question 15.
Write short note on ‘lightning conductor’.
Answer:
A lightning conductor is made up of long, thick metal rod having sharp spikes at its upper end. The spikes pointing towards the sky are fixed at the highest points of the building. The lower end of the metal rod is connected to a large copper or aluminium plate which is hurried deep inside the earth which is called earthing.

When a highly charged cloud passes over a tall building, it induces an opposite charge on the spikes. This charge quickly flows to the earth through the copper rod. Hence, the lightning discharge is prevented and the building is saved from damage.

Question 16.
Explain how lightning takes place?
Answer:
Normally air is a bad conductor of electricity. However, when two clouds having huge amount of positive and negative state charges approach each other, the air becomes a good conductor of electricity.

Thus the electrons from the negatively charged cloud push their way through air so as to reach the positively charged cloud. In doing so the air gets white hot and hence a dazzling bluish white streak of light is formed which is called lightning.

Question 17.
What precautions should be taken to provide protection against lightning?
Answer:
Precautions should be taken to provide protection against lightning:
Answer:
(i) Lightning conductor provides us a simple means to protect against damage due to lightning property and life.
(ii) When lightning strikes, it provide a path to the entire charge through it to the earth.
(iii) We should not stand under, I tree during a thunderstorms due to the air of lightning, because it destroys trees set it on fire.
(iv) Lightning conductor should be installed on large buildings and tall chimneys of factories.

Long Answer Type Questions

Question 1.
Describe water cycle in nature.
Answer:
Water constantly moves from the earth to the air and back again.
The constant circulation of water is known as the water cycle.

The water in seas, rivers, lakes, ponds or streams evaporates because of the heat of the sun.

Plants also give out large amounts of water from their leaves. The water vapour rises up. The air higher up in the atmosphere is cooler. This cools the water vapour and it condenses to form tiny drops of water on dust particles. These drops of water together form clouds. As the clouds get cooled further, the water drops become bigger and heavier. When they become too heavy, they fall to the earth as rain. The rain water enters the seas, rivers, lakes, ponds and streams and then evaporates again. Thus the water cycle in nature goes on.

Question 2.
Explain destructions caused by cyclones.
Answer:
Cyclones can be very destructive. Strong winds push water towards the shore even ;f the storm is hundreds of kilometres away. These are the first indications of an approaching cyclone. The water waves produced by the wind are so powerful that a person cannot overcome them.

The low pressure in the eye lifts water surface in the centre. The rising water may be as high as 3-12 metres. It appears like a water wall moving towards the shore. As a result the seawater enters the low-lying coastal areas, causing severe loss of life and property. It also reduces the fertility of the soil.

Continuous heavy rainfall may further worsen the flood situation. High speed winds accompanying a Cyclone can damage houses, telephones and other communication systems, trees, etc; causing tremendous loss of life and property.

Question 3.
What is lightning? How does ligthning takes place in the clouds?
Answer:
When the air gets white hot and hence a dazzling bluish white streck of light is framed, is called lightning. Normally air is a bad conductor of electricity. However, when two clouds having J e amount of positive and negative charges a proach each other, the air becomes a good conductor of electricity.

Thus the electrons from the negatively charged cloud push their way through air so as to reach to the positively charged cloud. In doing so air gets white hot and hence a dazzling bluish white hot and hence a dazzling bluish white streak of light is formed, which is called lightning. Because of this intense heat produced, the air suddenly expands and sends out huge pressure waves. These waves produced thunder.

Question 4.
How does lightning takes place between the clouds?
Answer:
Normally air is a bad conductor of electricity. However when few clouds having huge amount of positive and negative static charges approach each other, the air becomes a good conductor of electricity.

Thus the electrons from the negatively charged cloud push their way through air. So as to reach to the positively charged cloud. In doing so the air gets white hot and hence a dazzling bluish white streak of light is formed which is called lightning. Because of this intence heat produced, the air suddenly expands and sends out huge pressure causes. These waves produce thunder.

Winds, Storms and Cyclones Class 7 HBSE Notes

1. Air around us exerts pressure.
2. Air expands on heating and contracts on cooling.
3. Warm air rises up, whereas comparatively cooler air tends to sink towards the earth’s surface.
4. As warm air rises, air pressure at that place is reduced and the cooler air moves to that place.
5. The moving air is called wind.
6. Uneven heating on the earth is the main cause of wind movements.
7. Winds carrying water vapour bring rain.
8. 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.
9. The swift movement of the falling water droplets alongwith the rising air create lightning and sound. It is this event that we call a thunderstorm.
10. A cyclone is a storm in which the wind blows at a speed of about 300 km per hour. Cyclones develop over oceans but never close to the equator. They never originate from the land mass but may penetrate the margins of continents.
11. A cyclone is known by different names in different parts of the world. It is called a ‘hurricane’ in the
12. American continent. In Philippines and Japan its called a ‘typhoon’ and in Australia its called ‘willywillies’.
13. It has become easier to monitor cyclones with the help of advance technology like satellites and radars.
14. Self-help is the best help. Therefore, it is better to plan in advance and be ready with defence against any approaching cyclone.