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The Hydrologic Cycle: Geography NCERT Notes for UPSC
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NCERT notes on different NCERT important topics are considered important as per UPSC exam point of view as UPSC syllabus is based on NCERT format. One among such topics is “NCERT Notes: The Hydrological Cycle” as it is one of the important topics which is important for the UPSC exam along with other competitive exams like banking PO, SSC, state civil services exams, and so on.
In this article we will be covering topics based on NCERT Notes: The Hydrological Cycle like: types of rocks or classification of rocks, rock cycle, etc. Keeping all these things in mind, Testbook prepares the best quality NCERT Notes: Types of Rocks and covers all aspects related to this topic. By going through this note you can enhance your performance in UPSC and other competitive exams. So, Keep preparing from the Testbook.
The Hydrologic Cycle (UPSC Geography) NCERT Notes: Download PDF Here!
Hydrological Cycle Explained:
Hydrological cycle is also known as “water cycle” and there is a continuous exchange of water between the atmosphere, the oceans and the continents through the processes of evaporation, transpiration, condensation and precipitation. As the moisture which is present in the atmosphere is taken from water bodies through a process called evaporation and from plants through a process called transpiration (evapotranspiration). Further this evaporation undergoes condensation for the formation of clouds and once after the formation of clouds they fall down in the form of raindrops through precipitation process.
As the total amount of water vapour present in the atmosphere is constant, to maintain this there should be a proper balance between evapotranspiration and precipitation. And the cycle which maintains this stability is the Hydrological cycle.
This cycle does not have any starting and ending point, as it leads to continuous circulation of water present on the Earth which causes evolution of the Earth. The factor that assists hydrological cycle or water cycle is the sun, air currents to name a few.
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Process of the Water Cycle
Water cycle is completed in various stages or process they are:
Stage I: Evaporation and Transpiration:
In this process energy from the sun heats up the lakes, rivers, oceans, swamps and other water bodies which subsequently increase the temperature of the water present in them. This leads to evaporation of some water into air and the rising air current takes the vapour up in the sky.
Along with this process at the same time plants and trees also lose water to the atmosphere in the form of vapour which rises up in the sky.
Stage II: Condensation
In this process the vapour which rises up gets cooled because of cooler temperature in the surrounding. Because of this water vapour turns back into liquid through the condensation process.
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Stage III: Precipitation
In this process there occurs collisions in the cloud particles because of wind movements. Because of this clouds become water laden and they develop into rain bearing clouds and fall back onto the earth’s surface by the process known as precipitation.
They may fall on the Earth in the form of rain, hail, snow or sleet depending upon the temperature conditions.
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Stage IV: Runoff and Infiltration
After the precipitation process, precipitated water runs off into oceans, rivers and ground surface or is absorbed into the soil (infiltration).
After going through all these steps water is again ready to go through evaporation and resume earlier stages.
By going through all these processes of hydrological cycle or water cycle water is bringed back to people in the form of fresh water.
Water Vapour in Atmosphere
Volume of water vapour varies in the atmosphere from zero to four per cent by volume of the atmosphere i.e. on an average approx 2% in the atmosphere. Hygrometer is the instrument which is used to measure the amount of water vapour i.e. humidity in the atmosphere.
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Significance of Atmospheric Moisture
- Radiation is absorbed by water in both incoming and terrestrial form and by this it plays a crucial role in increasing the heat of the Earth surface.
- The quantity of energy stored in the atmosphere for the development of storms and cyclones is decided by the amount of water vapour present in the atmosphere.
- Rate of human body cooling capacity by the deviation in temperature is influenced by atmospheric moisture.
You might also like: NCERT notes on atmospheric pressure
Humidity
Amount of water vapour present in the air or atmosphere is known as Humidity. The term humidity is explained by relative humidity as a percentage of the maximum amount of water vapor the air can hold at the same temperature.
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| Also check the related Geography articles in the table below: | |
| Interior Structure Of The Earth | Earthquakes |
| The Geological History Of The Earth | The Geological History Of The Earth |
| Atmosphere | Cyclones And Anticyclones |
The Hydrologic Cycle NCERT Notes FAQs
What is the meaning of term specific humidity?
Weight of water vapour per unit weight of air is termed as specific humidity. It is not affected by changes in the pressure.
What is the importance of hydrological cycles in nature?
The hydrologic cycle plays a very crucial role because it is how water reaches plants, animals and us. Along with that it also provides people, animals and plants with water, it also moves things like nutrients, pathogens and sediment in and out of aquatic ecosystems.
What are the forms of hydrological cycle?
Hydrological cycle is a five step process i.e. condensation, precipitation, infiltration, runoff, and evapotranspiration. As the water cycle undergoes condensation steps for the formation of clouds, which undergoes precipitation processes under suitable climate.
What are the main components of the hydrological cycle?
The major components of the hydrologic cycle or water cycle are precipitation (rainfall, snowfall, hale, sleet, fog, dew, drizzle, etc.), interception, depression storage, evaporation, transpiration, infiltration, percolation, moisture storage in the unsaturated zone, and runoff (surface runoff, interflow, and baseflow).
What do you understand by the term evaporation?
As 71% of the Earth surface is covered by water which holds 97% of all the earth’s water reserves. It may be considered as the very first step of the water cycle or hydrologic cycle. The maximum evaporation is seen in the sub-tropics of the western North Atlantic and North Pacific because of the influence of the Gulf Stream and the Kuroshio Current, and in the trade wind zone of the southern oceans.