Basic Science Solutions for Class 7 Science Chapter 15 Wind, Storm And Rain are provided here with simple step-by-step explanations. These solutions for Wind, Storm And Rain are extremely popular among class 7 students for Science Wind, Storm And Rain Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Basic Science Book of class 7 Science Chapter 15 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Basic Science Solutions. All Basic Science Solutions for class 7 Science are prepared by experts and are 100% accurate.

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Wind refers to air in motion. It is caused by the uneven heating of different parts of the earth by the sun.

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A barometer is a scientific instrument, which measures atmospheric pressure.

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When cyclones raise the seawater, it leads to an increase in the sea level above its normal level. Such a situation is called storm surge.

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Eye of a cyclone is a low pressure circular area found at the centre of a cyclone.

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Winds swirl in anticlockwise direction around the centre of a cyclone in the northern hemisphere.

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Planetary winds are caused by permanent winds that blow due to uneven heating of the earth by the sun.

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The pressure exerted by atmospheric gases on the surface of the earth is called air pressure. It is an important factor that determines the weather of a place.
When air at a place gets heated, it expands and rises. The low pressure zone created by ascending air is filled by cooler and heavier air, which flows in from the surroundings. This causes the wind to blow. This cyclic movement of air is an important determinant of the weather at a given place.

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Thunderstorms develop when a column of hot air containing moisture comes in contact with cold air and cools down (moisture gets condensed and forms clouds). It can also develop when a fast blowing cold air meets a rising hot water column.

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Cyclones in eastern Pacific and western Atlantic are called hurricanes, whereas those in western Pacific are called typhoons.
Meteorologists give names to cyclones for easy reference while studying them.

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The permanent or planetary winds that blow from tropical belts towards the equator are called trade winds.
Sunlight keeps heating the air in the equatorial region. Here, the air rises and creates a low pressure zone. The cool and heavy surrounding air in the tropics starts moving towards the equator. They are called trade winds.

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During storm, the air above the roof moves faster than the air below it. This creates a high pressure zone below the roof and low pressure zone above it, causing an upthrust. This leads to rising up of roof and blowing it apart.

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Tornado is a form of storm wherein hot air keeps swirling around the low pressure zone at the centre.
It is formed when a vertical column of hot air, rotating violently, meets a current of cold air. The air from the centre gets sucked and a low pressure zone is created. The hot air in the column starts swirling around this low pressure zone and forms a twister or tornado.
Impacts of tornado:
(a) Roads and railway lines get destructed.
(b) Communication through telephone lines gets hindered.
(c) People lose their homes and belongings.

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Cyclones develop in tropical regions. The air above the sea gets heated by sunrays. On heating, the air expands and rises and causes the surrounding cold air to replace the hot air. This cold air again gets heated and rises. On the other hand, the air that was heated earlier, after rising, condenses and rushes downward. Similarly, on heating, the cold air again moves upward. This leads to a cyclic movement of air that starts swirling around the low pressure zone formed at the centre due to the rising column of hot air. The rotation of earth moves this air current towards low pressure regions, giving motion to it in a particular direction.

Cyclones are extremely destructive and can cause heavy loss of life and property. Hundreds of people lose their lives and homes. Communication and transportation systems get disrupted and life comes to a halt. They also cause harm to marine life, especially coral reefs. 

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Followings are the safety measures that people can take to protect themselves from cyclones:
 (i) People living in low lying areas should pay heed to cyclone warnings and they should always keep an eye on weather forecast.
(ii) During cyclones, one should stay indoors. Basements are the safest place during storms.
(iii) All the doors and windows should be shut properly and one must keep a stock of provisions for at least 4-5 days.
(iv) Outdoors should be avoided. However, if caught outdoors, one must vacate the vehicle immediately and look for a ditch or pit to hide.
(v)  During cyclones, it is good to turn off electricity supply because electric lines get uprooted during storms. Battery operated torches and radios should be kept ready for emergency.

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Monsoon winds carry rains to most parts of India between June and September. During summers, the Indian landmass becomes hotter than the surrounding seas. The moisture laden winds from Arabian sea and Bay of Bengal starts blowing towards the Indian landmass. On condensation, the winds pour all the moisture they have in the form of rains.

During winters, the landmass cools faster than the sea and wind starts blowing back to the sea. A portion of this wind picks up some moisture from Bay of Bengal and showers it on Tamil Nadu and parts of Kerala. This gives them winter monsoons.

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1. Twister and whirlwind are alternative names for a tornado.
2. An anemometer measures wind speed.
3. High pressure indicates cold weather.
4. A tornado over a sea is called a waterspout.
5. Scientists who study weather are called meteorologists.
6. The best place to be in during a tornado is the basement.
7. The cold, dry winds that blow over northern India during winter are called trade winds.



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