Why is water essential for life?


Water is essential for life because

(i) all life processes that take place in the cells require water medium.

(ii) water is needed for transportation of substances from one part of the body to the other in a dissolved form.

(iii) All the reactions in the body or within the cells occur between substances that are dissolved in water.

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What causes winds?


The uneven cooling of land and sea and the building of the low and high pressure area causes the air to move from a high pressure are to a low pressure area. This movemnet of the air from one region to the other region caused winds.

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How does the atmosphere act as a blanket?


Our atmosphere acts as a blanket because:

(i) It keeps the average temperature of the earth fairly constant during the day.

(ii) The atmosphere prevents the sudden increase in temperature during the daylight hours.

(iii) During the night, it slows down the escape of heat into outer space nad maintain ptimum temperature. 

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How is our atmosphere different from the atmosphere on Venus and Mars?


Atmosphere of the our atmosphere consists of a mixture of many gases like nitrogen, oxygen, carbon dioxide and water vapour that helps life to exist on the earth.

The major component of the atmosphere found on the Venus and Mars is carbon dioxide (95-97%), thus it does not support life.

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You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?


Prediction of the weather can be done by studying wind patterns which decide rainfall patterns. It also shows areas of low pressure and high pressure. these areas give an idea about the rainfall patteren of the area. For example in large part of India, rains are mostly brought by the South-West or North-East monsoons. This is how the weatherof the area is predicted taking into account the wind pattern. 

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