Frank Cce Everyday Science Solutions for Class 7 Science Chapter 8 Winds, Storms And Cyclones are provided here with simple step-by-step explanations. These solutions for Winds, Storms And Cyclones are extremely popular among class 7 students for Science Winds, Storms And Cyclones Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Frank Cce Everyday Science Book of class 7 Science Chapter 8 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Frank Cce Everyday Science Solutions. All Frank Cce Everyday Science Solutions for class 7 Science are prepared by experts and are 100% accurate.

Page No 117:

Question A:

Solve the following crossword puzzle:

figure

Across
3. A hazard causing destruction
4. It is the centre of a cyclone
5. A cyclone is called a ..................... in America

Down
1. A device to measure wind speed
2. Thich term means season in Arabic

Answer:

Page No 117:

Question B:

Fill in the blanks:
1. ................................. is a device to measure wind speed.
2. Envelop of air surrounding the earth surface ................................. .
3. Air ................................. on heating.
4. An alternative movement of hot and cold air is called ................................. current.
5. Air moves from a region of ................................. pressure to a region of ................................. pressure.
6. A cyclone is also called ................................. .
7. A hazard causing destruction is also called a ................................. .
8. ................................. are warm moist wind blowing from the sea to the land.

Answer:

1. Anemometer is a device to measure wind speed.
2. The envelop of air surrounding the earth's surface is called atmosphere.
3. Air expands on heating.
4. An alternative movement of hot and cold air is called convection current.
5. Air moves from a region of high pressure to a region of low pressure.
6. A cyclone is also called hurricane.
7. A hazard causing destruction is also called a natural disaster.
8. Summer monsoon winds are warm moist winds blowing from the sea to the land.

Page No 117:

Question C:

Match the item in Column A with the items in Column B:

Column A Column B
1. Anemometer (a) Wind direction
2. Centre of cyclone (b) Speed of wind
3. Tornado (c) Hurricane
4. Cyclone (d) Funnel-shaped
5. Rotation of the earth (e) Eye

Answer:

Column A Column B
1. Anemometer (b) Speed of wind
2. Centre of cyclone (e) Eye
3. Tornado (d) Funnel-shaped
4. Cyclone (c) Hurricane
5. Rotation of the earth (a) Wind direction



Page No 118:

Question 1:

Thunder and lighting happen at the same time but we see the lightning before we hear the thunder. Can you explain the reason for this phenomenon?

Answer:

Thunder is a sound that is due to lightning. Though thunder and lightning happen at the same time, we see the lightning before we hear the thunder because the speed of light is greater than the speed of sound in air. Therefore, we see the flash of lightning before we hear the sound of lightning (thunder).

Page No 118:

Question 2:

Why are cyclones more frequent along the coastline of India?

Answer:

The coastal areas are more vulnerable to cyclones because they are situated close to the sea.
Cyclones are huge revolving storms that develop over warm seas near the equator. These thunderstorms develop from the massive amount of moisture and heat of the rising warm air from the sea. These storms stir up the sea and create deadly waves and surges called storm surges. The water and rain from these storm surges move towards the inland areas with great power and flood the low-lying coastal areas.

Page No 118:

Question 3:

When cold water is poured over a tightly corked tin can containing steam, the tin can gets crushed. What crushes the tin can?

Answer:

When cold water is poured over a tightly corked tin can containing steam, the tin can gets crushed because of the atmospheric pressure acting on the outer surface of the can from all sides. When cold water is poured over a tightly corked can, the steam condenses into water and creates a partial vacuum inside the can. As there is no air pressure inside the can, the air pressure from outside acting on all sides on the tin crush it.

Page No 118:

Question 4:

Why do we not take shelter under an umbrella with a metallic head during lightning?

Answer:

Lightning is an atmospheric electric discharge that releases huge amounts of electric current and heat towards earth. Lightning strikes materials that provide an easier path of current flow to the ground. Metals are good conductors of heat and electricity. If we take shelter under an umbrella with a metallic head during lightning, the lightning may strike the metal head and the person holding the umbrella might get an electric shock because of the high discharge of electric current to the metal head that may pass through his body.

Page No 118:

Question D:

Write True (T) or False (F) against the following statements in the given brackets:
1. An anemometer measures the speed of sound. ( )
2. Cold air goes up but hot air goes down. ( )
3. Hurricane are wind currents. ( )
4. The centre of a cyclone is called the eye. ( )
5. The rotation of the earth affects the direction of winds. ( )
6. Convection current is the movement of hot and cold air. ( )

Answer:

1. False (F)
An anemometer measures the speed of the wind.

2. False (F)
Hot air goes up and cold air comes down.

3. False(F)
Hurricanes are huge revolving storms caused by winds blowing round the central area of low atmospheric pressure.

4. True (T)

5. True (T)

6. True (T)

Page No 118:

Question E:

Write these words in the correct place on the word map.

Storm with lighting and thunder   Eye   Low pressure   Funnel shaped   Cloudless

figure

Answer:



a. Eye

b. Cloudless

c. Storm with thunder and lightning

d. Funnel-shaped

e. Low pressure



Page No 119:

Question A.1:

Define atmospheric pressure.

Answer:

Atmospheric pressure is the pressure exerted by the atmosphere on the surface of the earth.

Page No 119:

Question A.2:

What is a convection current?

Answer:

The movement of particles or molecules within a fluid due to change in temperature is called convection current.

Page No 119:

Question A.3:

What is the use of an anemometer?

Answer:

Anemometer is a device used in weather station for measuring the speed of the wind.

Page No 119:

Question A.4:

What is a cyclone?

Answer:

A cyclone is a giant spinning storm caused by the winds blowing around a central region of low atmospheric pressure.

Page No 119:

Question A.5:

What is the eye of a cyclone?

Answer:

The centre of the cyclone with the lowest atmospheric pressure is called the eye of the cyclone.

Page No 119:

Question A.6:

Why do regions that are heated by the direct rays of the sun have low pressure?

Answer:

We know that hot air expands with increase in temperature. As the hot air expands, the molecules in the air move further apart from each other, become lighter and exert low pressure. This is why the regions that are heated by the direct rays of the sun have low pressure.

Page No 119:

Question A.7:

What name is given to the wind which blows off from the Indian Ocean during summer?

Answer:

Winds that blow from the Indian Ocean to the land during summer are called summer monsoon winds.

Page No 119:

Question A.8:

What is the name of a storm which is followed by lightning?

Answer:

Thunderstorm is the name of the storm that is followed by lightning.



Page No 120:

Question B.1:

How can you prove hot air is light and rises up?

Answer:



We can prove hot air is light, and that it rises, by the following activity:

Take two large paper bags and tie them to the two ends of a ruler with strings. Now, tie a piece of string at the centre of the ruler, so that the ruler is balanced on both sides. Next, place a lighted candle below one of the paper bags and observe. The experimental arrangement is as shown below. We observe that the balance of the bags is disturbed.

Inference: The balance of the bags is disturbed because the air inside the bag gets heated up by the candle. As the air heats up, the particles in the air move further apart from each other. Therefore, hot air is light and  rises upwards, causing a disturbance in the balance of the bags.

Conclusion: We can conclude that hot air is light and rises up.

Page No 120:

Question B.2:

What are monsoon winds?

Answer:

Monsoon winds are seasonal reversing winds that are due to the uneven heating of the continents (land) and oceans. They occur on an annual basis. Winds that blow from the Indian Ocean towards the Indian subcontinent in one season are reversed from land towards the ocean in another season of the year.

Page No 120:

Question B.3:

What is the structure of a cyclone?

Answer:

Cyclone is a huge revolving storm that develops over the warm tropical seas and oceans near the equator.

 Structure of a cyclone:

1. The centre of the cyclone is called the eye of the cyclone. It is the area of lowest atmospheric pressure.

2. The speed of the winds around the centre of the cyclone (eye) can reach 200 km/h; a tropical storm developed from the thunderstorms can pump out 2 million tonnes/second of air.

3. The diameter of the eye ranges from 10 km to 30 km.

4. The centre of the cyclone is a calm and cloudless region.

Page No 120:

Question B.4:

What is a tornado? What damage can it cause?

Answer:

A tornado is a violent windstorm circling around the centre of a low pressure area. It is a rotating column of air extending from a thunderstorm to the ground.

Tornado consists of very powerful winds, and a violent tornado can travel with the speed of 300 km/h. The diameter of the tornado can range from as small as a metre to as large as several kilometres or more wider. Therefore, tornado is capable of causing tremendous loss of life and property, destroying buildings and other structures, damaging the power poles and communication systems, hurling vehicles hundreds of yards away and uprooting the trees.

Page No 120:

Question B.5:

What are thunderstorms? When does a storm occur?

Answer:

Thunderstorms are the storms with thunder and lightning. Thunderstorms are due to the uneven heating of air around the earth. The earth's surface is heated by the surface of the sun. Air above the earth's surface is heated by conduction. As the temperature increases, strong and upward rising winds are produced. This upward rising of winds results in condensation along with release of massive amounts of heat. This rapid movement of condensed moisture along with the rising air creates lightning and thunder.

Page No 120:

Question B.6:

How does a tropical storm develop?

Answer:

Tropical storm develops from the warm tropical moisture-bearing clouds over the open seas and oceans. When the sun's rays heats up and quickly rises the air, it creates a region of very low pressure. When this warm air rises up and condenses into thunder clouds, a huge amount of heat is released. This massive heat combined with moisture results in the formation of thunderstorms, which, in turn, leads to the development of tropical storm.

Page No 120:

Question B.7:

What are storm surges?

Answer:

Storm surges are a rise in the sea level that are caused by winds from severe storms. The storms generate strong winds and churn up the sea, thereby causing huge waves and surges of water called storm surges. Storm surges push water into inland areas with deadly power and cause floods in low-lying coastal areas.

Page No 120:

Question B.8:

Why are most of the Indian states vulnerable to thunderstorm and cyclones?

Answer:

Thunderstorms are storms with lightning and thunder that are due to the convection of air in hot and humid areas. Cyclones begin as thunderstorms, which develop over warm tropical seas near the equator. Hence, tropical regions are more vulnerable to thunderstorms and cyclones. As India passes through Tropic of Cancer, which is at a latitude of 23o30' from the equator, it experiences a tropical climate. Therefore, most of the Indian states, especially the east coast, are more vulnerable to thunderstorms and cyclones.

Page No 120:

Question C.1:

What are winter monsoon winds?

Answer:

Monsoon winds are seasonal reversing winds that are caused by the uneven heating of the continents and oceans.
Winter monsoon winds: During winter, the continent cools off quickly and creates a high pressure region in the interior of the continent. However, the Indian Ocean in the south has lower air pressure because the ocean is warmer than the land. As a result, cold winds blow from the interior of the continent towards the ocean. These winds that blow from the continent towards the ocean in winter are called winter monsoon winds.

Page No 120:

Question C.2:

How does uneven heating between the equator and the poles cause winds to blow?

Answer:

The equator receives maximum amount of heat from the sun because of its position in relation to the sun. The poles receive minimum amount of sunlight because the sun's rays fall at a slanting angle and create a high pressure region. The air between the latitudes of 30° and 60° are warmer compared to the air at the poles. Warm air at the equator rises and creates a low pressure near the earth's surface. This void is filled by the cold and dense air from the poles. This uneven heating of the equator and the poles lead to a difference in the air temperature, which is responsible for the generation of wind currents.

Page No 120:

Question C.3:

What is meant by saying that air expands on heating? Support your answer with the help of an activity.

Answer:

When air is heated, the molecules of hot air move faster than particles of cold air and move further apart from each other. Hence, we say that air expands on heating.

Activity:

Take a balloon and press it flat so that there is no air inside it. Take an empty bottle and tie the balloon around it with the help of a rubber band so that the air doesn't escape from the bottle. Take water in a beaker and boil it. Place the bottle in the boiling water and observe.

Observation: We observe the balloon is inflated.

Inference: The air in the bottle was heated by boiling water. This heat caused the air to expand inside the bottle and further move and enter into the balloon, thereby causing it to inflate.

Conclusion: Air expands on heating.

Page No 120:

Question C.4:

Explain how uneven heating of land and ocean water in summer generates wind.

Answer:

In summers, during the daytime, the land (near the equator) is heated faster than the sea water. The air above the land is heated by radiation. The warm air rises up and creates a low pressure region. This void is filled by the cool air from the sea. This uneven heating of  land and ocean water lead to difference in temperature of air, which is responsible for generation of winds.

Page No 120:

Question C.5:

What are natural disasters? Describe how a cyclone causes widespread destruction leading to a great loss of life and property.

Answer:

Disasters that are due to natural calamities are called natural disasters.

Cyclone causes widespread destruction leading to a great loss of life and property. Following are the hazards associated with cyclone:

1. The winds are so fierce and strong that they have the power to topple fences, trees, power lines and sheds. The fierce winds with a speed of 200 km/h cause the buildings to collapse and houses to blow away and kill many people.

2. A cyclone stirs up the sea and causes huge waves and surges of water that are called storm surges. The water from the storm surges moves into the inland areas with great power and causes floods in the coastal regions. Cyclone causes heavy rainfalls and floods along the coastal regions.

 

Page No 120:

Question C.6:

What safety precautions should be taken during storm and lightning?

Answer:

Following are the safety precautions that should be taken during storm and lightning:
1. Do not take shelter under an umbrella with a metal head because metal is a good conductor of heat and may cause electrocution.
2. Avoid taking shelter under an isolated tree.
3. Do not sit near windows or take shelter in metal sheds and garages.
4. Avoid swimming in a pool during thunderstorms. Taking shelter inside a building is safe.

Page No 120:

Question C.7:

How is the forecasting of cyclones done in India?

Answer:

In India, cyclone forecasting is done in the six cyclone warning centres located at Chennai, Mumbai, Vishakapatnam, Bhubaneshwar, Kolkata and Ahmedabad.

Following are the steps involved in forecasting of cyclone:
1. Cyclones are detected with the help of powerful cyclone detection radars (INSAT).
2. Cyclone alert is issued two days in advance and the message is disseminated to the people through repeated radio broadcasts and TV telecasts for evacuation of people and animals to safer places.
3. Cyclone warning is issued 24 hours in advance before the expected time of commencement of the disaster and is repeatedly disseminated to the people via television, press bulletins and radio.

Page No 120:

Question C.8:

What action should the public take when a cyclone occurs?

Answer:

Public should take following actions when a cyclone occurs:

1. Cyclone warnings issued by the governmental and non-governmental agencies should never be ignored.

2. People should be prepared to shift their household items, domestic animals and vehicles to safer places.

3. People should have helpline numbers of police, fire brigade and medical resources ready to use during emergency.

4. Ensure that children are away from all the electrical appliances and do not touch wet switches and broken power lines in the cyclone-affected areas.

5. Cooperation with the rescue operation team is very important during emergency for safer evacuation.



View NCERT Solutions for all chapters of Class 7