GL TEACHER SCHOOL EDUCATION
DEPARTMENT JAMMU AND KASHMIR
Lesson 8
WINDS, STORMS AND CYCLONES
Points to Remember
- Moving air is called wind.
- Cyclones are destructive in nature.
- Orissa was hit by a cyclone on 18 October, 1999.
- Cyclones have high wind speeds.
- Air exerts pressure and it expands on heating.
- Increase wind speed is accompanied by a reduced air pressure.
- Wind currents are generated due to temperature difference on the earth.
- Monsoon winds carry water and it rains.
- Thunder storms are caused by swift movement of falling
- water droplets and light and sound created by rising air.
- Continuous heavy rainfall leads to flood situation.
- Hurricane in America, Typhoon in Japan are nothing else but cyclones only.
- Tornadoes are dark funnel shaped clouds that reach from the sky to the ground.
- All these natural disasters-cyclones, thunder storms, tornadoes lead to destruction of property, lives, communication systems, trees etc.
- Special measures are taken into consideration during the disasters.
- Cyclone-alert is issued 48 hours in advance of any expected storm by satellites and radars.
- • Self-help is the best help. Thus it is better to plan in advance and to be ready to defend any approaching cyclone.
- Anemometer is instrument to measure the wind speed.
- Wind. The moving air is called wind.
- Monsoon winds. The winds coming from sea which carry water vapours in them are called monsoon winds.
- Tornado. A dark funnel shaped cloud that reaches from the sky to the ground.
- Cyclone. A violently rotating mass of air in atmosphere is called cyclone.
- Anemometer. An instrument to measure wind speed.
TEXT BOOK EXERCISES
Q. 1. Fill in the missing word in the blank spaces in the following statements.
(i) Wind is ....... air.
(ii) Winds are generated due to........ heating on the earth.
(iii) Near the earth's surface. air rises up whereas ........ air comes down.
(iv) Air moves from a region of ........to a region of ......... pressure
Ans. (i) moving (ii) uneven (iii) warm, cooler (iv) high, low.
Q. 2. Suggest two methods to find out wind direction at a given place.
Ans. Wind direction at a given place may be found out by ;
(i) using a Charkhi (Pulley)
(ii) flying a kite.
Q. 3. State two experiences that made you think that air exerts pressure (other than those given in the text).
Ans. Examples of air exerting pressure.
(i) The cold drink sucked by a pipe is an example of air exerting pressure. When air is sucked through the pipe the air inside the pipe (straw) gets evacuated but outside air is exerting pressure on liquid as a result of which liquid rises in the pipe.
(ii) When mercury is filled in a test tube and it is inverted
in a trough containing mercury. The level of mercury in test tube will fall to 76 cm which is due to atmospheric pressure
Q. 4. You want to buy a house ? Would you like to buy a house having windows but no ventilators Explain your answer. ?
Ans. A good house is one which has both windows and ventilators. Windows are meant for fresh air to circulate in the rooms. The warm air rises up and for this ventilators are required for escaping of hot air. If there are no ventilators then stale and hot air will remain in room, thus will contaminate it.
Q. 5. Explain why holes are made in hanging banners and hoardings.
Ans. Holes are made in hanging banners and hoardings to let the strong winds of high speed pass through them. If these holes are not made the high speed winds will either carry the hanging banners or hoarding along with it to far off places or will tear them apart with their pressure.
Q. 6. How will you help your neighbours in case cyclone approaches your village/town?
Ans. Helping neighbours during cyclones :
(i) Moving them to cyclone shelters.
(ii) Saving shifting their household property to safer places.
(iii) Providing them medical aid.
Q. 7. What planning is required to deal with situation created by a cyclone ?
Ans. Plans to deal with situation created by cyclone.
(i) Shift essential household goods, domestic animals to safer places.
(ii) Keep handy phone numbers of all emergency services like Police, Fire brigade and medical centres.
(ii) Avoid driving on roads through standing water.
Q. 8. Which of the following place is unlikely to be affected by a cyclone :
(i) Chennai. (ii) Mangalore
(iv) Puri. (iii) Amritsar
Ans. (iii) Amritsar.
Q. 9. Which of the statements given below is correct :
(i) In winter the winds flow from land to the oceans.
(ii) In summer the winds flow from land towards the ocean.
(iii) A cyclone is formed by a very high pressure system with very speed winds revolving around it.
(iv) The coastline of India is not vulnerable to cyclones.
Ans. (i) correct (ii) incorrect (iii) incorrect (iv) incorrect.
SHORT ANSWER QUESTIONS
Q. 1. What is a tornado shelter ?
Ans. Tornado Shelter. A room situated deep inside or underground having no windows is a Tornado Shelter.
Q. 2. What is an anemometer?
Ans. Anemometer. The instrument that measures the wind speed is called an anemometer.
Q. 3. What is a cyclone ? On which factors it depends?
Ans. Cyclone. A low pressure system with very high speed winds revolving around it is called cyclone. Wind speed, wind direction, humidity and temperature are some factors which contribute to the development of a cyclone.
Q. 4. Give a brief account of formation of thunderstorms.
Ans. Formation of Thunderstorms: In hot, humid climate, the rising temperature produces strong winds. These rise upwards and carry lots of water droplets. These water droplets freeze at height and fall downwards. The swift falling water droplets along with rising air create lightening and sound. This event is thunderstorm.
Q. 5. How are clouds important to farmers ?
Ans. Importance of clouds to farmers.
(i) Clouds are important for harvest. If harvest is good, farmers are happy.
(ii) Clouds bring rains.
(ii) They make the weather pleasant.
Q. 6. Why do winds blow ?
Ans. Winds blow due to difference in temperature or difference in pressure of two regions.
Q. 7. What is the cause of air pressure?
Ans. Cause of air pressure. The air pressure arises due to constant collision of molecules of the gases present in the air with walls of the containing vessels.
LONG ANSWER QUESTIONS
Q. 1. Give a brief account of Orissa disaster.
Ans. Orissa disaster. Two cyclones hit Orissa in year 1999 on 18 October and 29 October. The wind speeds of cyclones were 200 km/h and 260 km/h respectively. The cyclone destroyed about 45,000 houses making 7,00,000 people homeless. Properties worth crores of rupees was destroyed. also affected. Agriculture, transport, communication and electric supply was also affected.
Q. 2. How will you show air expands on heating?
Ans. Experiment to show air expands on heating. Take a boiling tube and fix a balloon tightly over the neck of the tube. Insert the boiling tube with balloon into a beaker containing hot water. After 2-3 minutes the balloon will start inflating which shows that air expands on heating.
Q. 3. How monsoon winds are formed ?
Ans. In summers, land near equator warms up faster and temperature of land is higher than that of water in oceans. The air over land gets heated and rises. To take its place, the winds from oceans start moving towards the land. These winds are full of water and are known as Monsoon winds.
Q. 4. What precautions should be taken when thunderstorm is accompanied by lightening?
Ans. Precautions to be taken during lightening in thunderstorm.
(i) Never take shelter under an isolated tree.
(ii) Do not lie on ground.
(iii) Do not use umbrella with a metallic rod.
(iv) Window, open garages, storage sheds, metal sheds are not safe places.
(v) Never stay in water.
(vi) Car or bus are safe place to take shelter.
Q. 5. Describe the structure of cyclone in brief.
Ans. Structure of a cyclone. A large cyclone is a violently rotating mass of air with a centre calm area called eye of the storm. The diameter of eye lies between 10 to 30 km. This region is free of clouds and has low winds. Eye is surrounded by a cloud region of 150 km in size. It consists of high speed winds (150-200 km/h) and thick cloud with heavy rain. The wind speed gradually decreases away from this region......
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