Winds Storms And Cyclones - Class 7 Physics - Extra Questions

What is a Land Breeze, and how is it produced?

During night land cools more quickly than seawater. So hot air above the sea rises up and cold air moves from the land towards the sea This is called land breeze.
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How do convection currents help in ventilation of a room?

The carbon dioxide rich exhalded air , being warm and lighter rises up It then passes out through the ventilators in a room This causes a drop in pressure within the room Thus the cold can fresh air enters from the doors and windows to fill up the gap This continuous circulation of air is maintained with the room by convection currents 


How is air useful for us ?

Air is a very useful natural resource, just like water, and has many uses. The most important aspect of air is that it keeps all living things on Earth alive by providing oxygen.

Living things are not the only things that use oxygen. Candles, fire, iron, picked fruit and vegetables all change when exposed to oxygen. Candles and fire require oxygen to continue burning. Iron will rust when exposed to water and oxygen. Fruit and vegetables will change colour and eventually go mouldy due to the moisture and oxygen in the air.

Air can also be used to produce energy. The movement of air can be transferred into energy through windmills. Air can also provide energy to boats, parachutes, things that fly (refer to Topic 3) and to the weather (tornadoes, cyclones).


State two experiences that made you think that air exerts pressure.

(i) Balloons and balls can be used only when they are inflated with air. When balloon is overfilled with air it bursts due to excessive air pressure.
(ii) Compressed air is used in the brake system or stopping trains.


Suggest two methods to find out wind direction at a give place.

Two methods are:

(i) Take a piece of paper in your hand. Allow it to fall from your hand. It will flow in the direction in which wind is blowing.

(ii) You can also use a wind-pane which helps us to know the accurate wind direction.


Winds are generated due to ___________ heating on the earth.

Wind is air in motion. It is produced by the uneven heating of the earth's surface by the sun. Since the earth's surface is made of various land and water formations, it absorbs the sun's radiation unevenly. Two factors are necessary to specify wind: speed and direction.


Fill the missing words in the blank spaces in the following statements.
Air moves from a region of ______ pressure to a region of ______  pressure.

Air moves from a region of high pressure to a region of low pressure. The greater the difference in pressure, the faster the air moves.


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

The flowing methods can be used to get the directions of wind. 
1. Take some fine the lighter sand in your hand and slowly step it off. Movement of dust particles in a particular direction will give the direction of wind flowing. 
2. Fly a Kite, the direction of the kite flies shall be the wind direction. 
3. Take bit of paper on your palm. The piece will fly in the direction of wind is blowing, 
4. Use anemometes or wind wane. 


Fill the missing words in the blank spaces in the following statements.
Near the earths surface _____ air rises up whereas ______ air comes down.

The hot air near the earth's surface is at a higher temperature so it gets lightweight and rises up and the cold air which has more weight comes down to take the space of the hot air.

Hot air goes up in the atmosphere and the cold air comes down to the surface.



Fill the missing words in the blank spaces in the following statements.
Wind is ............  air.

Wind is $$\textbf{moving}$$ air


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

In case cyclone approaches, we should help our neighbours in the following ways : 
1. By helping them in moving to cyclone shelters and other safe 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 centers when required. 
4. By not pressurising the rescue force by making undue demands. 


 Why do you think that the cable connection in the house becomes dangerous during lightning?

A cloud-to-ground lightning bolt's main objective is to find the path of least resistance from the cloud to deep into the ground. Most houses are filled with many potential routes for lightning to follow in its journey. This can include gas and water pipes, electric lines, phone lines, cable TV/internet lines, gutters, downspouts, metal window frames - anything conductive in a house is for the lightning to follow. Lightning doesn't need conductive objects to reach the ground, however - it's just forged its way through miles of air, so conductive objects in a house are a mere 'convenience' that it will use if they are available.

Lightning passing through a house will often 'branch' and utilize more than one path to ground at a time. It can also jump through the air from one conductive path to another in what is called a side flash. For example, lightning may first connect to electric lines in the attic of a house, then jump to better-grounded water pipes on the first or second floor. Lightning can connect to gutters, then jump to a window frame as a 'stepping stone' to the electrical system or water pipes. All or parts of bolts have been seen jumping from wall outlets to sink faucets and even across rooms!



Listening to songs by an iPod during a thunderstorm is not safe. Why?

  • If you use an iPod during a thunderstorm it may create an induced magnetic field due to the lighting. The induced magnetic field can easily pass through the eardrum by breaking through it and thus damage our ears. This can even cause serious damage to the human brain.


Make a lactometer with ball point refill. What would you do to make the refill stand vertically straight?

TO make a lactometer with ball point refill, follow the given steps :

1.       Take an empty ball pen refill with a metal point at the bottom.

2.       Take a boiling tube and fill it with water.

3.       Put the refill in the water with metallic point.

4.       To make the refill stand in water, insert a small eraser piece in the refill at the centre.

5.       Mark the point  with marker up to which the refill is above the water.

6.       Now, empty the boiling tube with water and fill it with milk.

7.       Again put the refill in milk and mark the point which shows the part which is above the surface of milk.

8.       Further we can add , milk water mixture in the boiling tube and repeat the same step 8. 

9.       we can now compare and test whether water is added to milk or not.



A flag mounted on a flag post near the sea coast flutters in
the direction of sea. At what time of the day does
this happen at midnight or in the afternoon?

This incident , the flag will flutter in the direction of sea when it is midnight because at night time the sea becomes more hot than land and the air above sea traps heat and rises up due to which pressure difference is created and the cool air above land reaches the sea in order to maintain balance , so the flag will flutter in the direction of sea at midnight time and this phenomena is also called land breeze.


Why is Chandigarh unlikely to be affected by a cyclone?

Chandigarh is most unlikely to be affected by cyclone because it is not near to coastal line and has no sea or ocean near it, as it is surrounded by other states. Cyclones occur near coastal areas because they water bodies near them as to initiate the process and also the temperature of that water body should be suitable too, to generate the cyclone.


Fill in the blanks.

i) Air around us exerts ________.
ii) The moving air is called _________.
iii)  The main cause of wind movement is uneven_______________ on the earth.
iv) High speed wind can cause cyclone in regions of ______________

pressure.

i) Pressure.

ii) Wind.

iii) Heating.
iv) Low.



To expel hot air out of the kitchen, 'A' has an exhaust fan fitted on the window of her kitchen and 'B' has a similar exhaust fan fitted on the wall near the ceiling of her kitchen. Which of the exhaust fan will expel the hot air more, effectively? Explain why?

In the kitchen of 'B' ,warm air rises up and her exhaust fan is at standard height as comparison to, A. so, it will expel the hot air more effectively. 


Match Column I with Column II. There can be more than one match.

As we know that warm air  expands and rises up as it is lighter.Cool air sinks because it  contracts so it becomes heavy and  compressed and has high pressure.So it sinks down.

So the answer to the question is,

On heating air, it expands and rises.

On cooling air, it contracts and descends.



Figure shows a diagrammatic representation of trees in the afternoon along a sea coast. State on which side is the sea, A or B? Give reasons for your choice.


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The ground gets heated faster during the afternoon. Air over the ground becomes hotter and rises up. that develop pressure differences between sea areas and ground. therefore cold air started to flow from sea to ground that's result all trees near to sea bend towards the ground. In the given figure A represent ground side whereas B represents Sea side.



Why is it advisable not to shut all the doors and windows
during a storm?

As we know that the storm is simply accompanied by strong winds(high speed) and as we know that the high-speed winds have low pressure , so if we close all the doors and windows when a storm occurs then the pressure inside the house will remain the same as before(high pressure than storm) but due to storm the pressure outside the house has changed and has lowered on the roof of the house, so the pressure difference created will try to neutralize by taking off the roof of the house, so that is why we should not close all the doors and windows when a storm comes.


State whether the following statements are True or False:

i) If wind flows from land to the ocean, then it is daytime.

ii) A very high-pressure system, with very high-speed wind surrounding it forms a cyclone.

iii) The coastline of India is not vulnerable to cyclones. 

iv) Warm air is lighter than cool air.

(i). False.

If wind flows from ocean to the land then it is daytime and is called sea breeze, because in daytime the land gets heated and the air above it expands and rises up, and there is the formation of low pressure are above it. (If wind flows from ocean to land then it is daytime and in the opposite condition it is night time.)

(ii). False.

A cyclone is a natural disaster caused by the warming of air by water vapors through ocean and revolving of high-speed winds around a low-pressure area.(not a high-pressure area)

(iii). False.

The coastlines of India are highly vulnerable to cyclones and also the east coast is more vulnerable to cyclones with high speed and with a high number of cyclones.

The two cyclones in Odisha are an example of the vulnerability of cyclones to India. (The east coast is more likely to welcome cyclones.)

(iv). True.

As we know that warm air expands and has low pressure and hence it has the same mass but expanded volume or space, hence it rises up and is said that it is lighter than cool air.

For example – the sea breeze and land breeze system prove the fact.




Suggest some precautions to be taken to prevent the roof of a tin sheet from flying away during a fierce wind storm.

Some precautions to prevent the roof of a tin sheet from flying away during a fierce wind storm are given below:

a) We should screw it tight. The tin sheet should be laid properly on an iron frame.

b) We should put heavy stone or other thing on it.



 



The picture in Figure shows tree line along the sea coast on an island near the equator. As shown, the tree tops are permanently bent in one direction. Are the trees bent towards the sea or away from it? Explain
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In the given figure.

Yes,
all the trees are bent towards the sea or away from it.

During the day time, the wind flows in the direction of sea to
land. This time, the land gets warmer more speedily as compared
to the sea. So, the air above the land becomes warm and lighter that rises up in the sky. Thus, the top
of the bent trees shows the moving direction of the wind from sea to land.



When strong/high speed wind blows an umbrella held upright at times gets upturned. Explain the reason.

The high-speed or strong wind passing through an umbrella creates a low pressure. So, the pressure an umbrella gets upturn.


Fill the missing word in the blank spaces in the following statements :
Winds are generated due to______


Wind is air in motion. It is produced by the 
  • $$\textbf{uneven heating of the earth's surface by the sun:}$$ Since the earth's surface is made of various land and water formations, it absorbs the sun's radiation unevenly. 
  • $$\textbf{uneven heating of land and water:}$$ In summer, the land warms up faster and the temperature of the land is higher than that of water in the oceans. The air over the land gets heated and rises. This causes the winds to flow from the oceans towards the land. These are monsoon winds. In winter, the direction of the wind flow gets reversed; it flows from the land to the ocean  


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

We can experience air pressure in our daily activities such as 
1. When we blow a balloon, the balloon becomes tight. If we try to fill more air, then the balloon bursts after an extent. This happens because air exerts pressure. 
2. Trees leaves and branches flutter due to pressure exerted by air in the form of wind. 


Identify the names of six natural phenomena from the following word diagram given as Figure.
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The
names of six natural phenomena:



i) HURRICANE



ii) TYPHOON



iii)
TORNADO

iv) LIGHTING



v)  CYCLONE



vi) 
THUNDERSTORM


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How do you know that air exerts pressure? Give some examples. 

  • Material Required: Bottle, crumpled piece of paper
  • Method: Crumple a small piece of paper into a ball of a size smaller than the mouth of an empty bottle. Hold the empty bottle on its side and place the paper ball just inside its mouth. Now try to blow on the ball to force it into the bottle.
  • Observation: The paper does not move inside.
  • Inference: The air pressure at the mouth of the bottle is reduced due to more speed. This forces the air out from the bottle. This prevents the crumpled paper ball to move inside.

Moving air exerts pressure, when the air blows we can see the fluttering of leaves in the tree, banners and flags. 

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Describe an activity to demonstrate that warm air is lighter than cool air.

i) Take two same sizes of empty paper bags.

ii)  On the two ends of a wooden stick hang the both of bags in an upturned position.

iii)  In the centre of stick tie a portion of thread.

iv)  According to the figure (A), hold the stick by the thread in balance.

v)  According to the figure (B), place the burning candle below one of the bags.

vi) Now, you will observe unbalanced stick. This represents that as the warm/temperate air rises up and it pushes the bag over the candle.

vii) Now we can say that when air is heated, it expands and also occupies more space. So, we can conclude that warm air is lighter as compared to cool air.



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What is an anemometer? 

An anemometer is a device used for measuring wind speed and direction
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The centre of a cyclone is calm and it is called as _______ of the storm.

The center of a cyclone is a calm area. It is called the eye of the storm.
The formation of a very low-pressure system with very high-speed winds revolving around is known as a cyclone. 


Wind speed plays an important role in the formation of ___. 

All storms are low pressure systems. Thus, wind speed plays an important role in the formation of$$\textbf{ storms}$$


Wind currents are generated due to ___ heating on the earth. 

We know poles are cooler than equator as highest intensity of the sun's heat and light falls on the equator and it reduces as we go either side of the equator towards the poles. Cooler air from the surrounding areas of the poles comes towards the equator to fill the place of warm air which rises up due to sun's heating. Hence, wind currents are generated due to $$\textbf{uneven heating}$$ of the earth.


The monsoon winds carry water and it _____ .

The winds from the oceans carry water and bring $$\textbf{rain}$$.It is a part of the water cycle. The monsoon winds carry water and it $$\textbf{ rain}$$


The instrument that, measures the wind speed is an ____.


The instrument that measures the wind speed is called an $$\textbf{anemometer}$$.


How monsoon around formed? 

In summer, near the equator the land warms up faster and most of the time the temperature of die land is higher than that of water in the oceans. The air over the land gets heated and rises. This causes the winds to flow from the r oceans towards the land are the monsoon winds. 


 How thunderstorm occurs? 

Thunderstorms develop in hot, humid tropical areas like India very frequently. The rising temperature produces strong upward rising winds. These winds carry water droplets upwards where they freeze and fall down again. The swift movement of the falling water droplets along with the rising air creates lightning and sound this the thunderstorm.


The warm air is..............than cold air.

Warm air $$\textbf{is lighter}$$ than cold air. Because the cold air contains some of the molecules of water.


The monsoon is derived from the Arabic word ___, which means___. 

The word “monsoon” is derived from the Arabic word $$\textbf{mausim}$$ which means $$\textbf{season}$$. Basically, it describes a seasonal wind shift over a region that is usually accompanied by a dramatic increase in precipitation


The advanced technology which monitor cyclones are ___ and ____. 

Weather Radars and Satellites are used to track the cyclones as they are produced.


Class 7 Physics Extra Questions