NCERT Class 7 Geography Chapter 5: Air Completes Notes Part 1 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Water Cycle

Now we will start with basic concept of water cycle. What happens is? First of all talk about presence of water.

Types of Water

When we talk about the saline water and fresh water. it՚s important to note that most of the water sources that we have our saline as compare to fresh water which forms miniscule percentage of the total water system.

Water Cycle

Now when we talk about water cycle, basically happens is you have the water surface or you have the ocean surface that exist. You have Evaporation that occurs now how does water move from the ocean surface to the clouds there are various ways.

  1. Process of Evaporation: that means the water heats up and that water goes up.
  2. Transpiration: this Transpiration occurs from the leaves or the surface of leaves from plants and forest.
  3. Condensation: now this water heats up it moves up and it reaches a saturation point and that is known as condensation. The cooling of water occurs and that cooling reach though condensation. Condensation you have formation of clouds.
  4. Precipitation: now once you have the clouds that are formed and they are fully saturated they would ultimately pour down and this pouring down occurs in the form of rainfall and this rainfall, its subsidiary like rainfall, snowfall all these are known as forms of Precipitation. They can occur numerous ways. These precipitation when comes on it can either go as surface runoff and directly into ocean or as sub surface water that goes underground. So water behaves like terrarium. that՚s mean you have kind of whole lot of system that undergoes and this same water that is circulate from the ocean, plants and back to ocean and this process has been happening for decades and decades and its simply the recycling of water that takes place.

Distribution of Water

Distribution of Water

The distribution of quarter as I said most of the water is accounted with the oceans which include nearly 97 % and of the remaining 3 % we have fresh water sources. so you have kind of 97 % which is saline water and the remaining constitutes the freshwater sources of which also you have some sections Which is a form of salt lakes. If I try to classify or distribute the freshwater that exist in to the globe I would say if I take 12 spoon of water this is a kind of simple demonstration to explain the proportion of water into each element of this 12 spoon of water 9 spoons would form the ice caps 2 spoons would form the underground water 1 spoon would form the rivers and only half a spoon would form the freshwater lakes that exist on the earth surface. So if you look at the global picture or the globe itself we try to understand I would have a kind of imaginative understanding of how much proportion of water lies at saline water. However the fresh water present and a kind of mere amount on miniscule amount are mainly concentrated in the ice caps that exist followed by a kind of very low section as ground water. There is reverse and finally as the freshwater lake bodies.

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