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The water which we use has originated from lakes, ponds, seas and together they end up back to the ocean. A huge body of saltwater is what we refer to as an ocean. The water that falls on land in the form of snow and rain goes back to the oceans sooner or later. The snow in the mountains melts and flows down as rivers or streams that flow back again to seas and oceans. The rainwater fills up lakes and ponds. Some of the rainwater either gets absorbed by the ground or goes back in the air by the process of evaporation and transpiration.
Read Also: Importance of water cycle
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Key Terms:Water, Ocean, Water cycle, Evaporation, Transpiration, Condensation, Precipitation, Runoff, and Infiltration
How is Water returned back to the Ocean?
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Water cycle is an important process for returning water back to the oceans. Water cycle is a journey of water from the oceans and other large bodies of water to the land and from the land back to those water bodies. The water cycle is also called a hydrologic cycle. There are three phases of water: solid, liquid, gas in which the water travels. The process of returning water back to the oceans is nothing but the water cycle.
The water cycles
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The sun is the primary source that heats up a large surface area of oceans causing the water from oceans to evaporate. Evaporation is the process when liquid water on the surface turns into water vapour in the atmosphere.
- The water vapour gets carried away by the atmospheric air currents where it cools down and condenses to form clouds. Condensation of water vapour releases latent heat that plays an important role in balancing heat on Earth. Clouds are an accumulation of fine water droplets at a very low temperature.
- The particles of cloud collide and their electrical discharge results in precipitation of water droplets to the ground. This process can be in the form ofrain, snow, hail etc.
- As the water precipitates, some of it gets absorbed by the soil and enters the process of transpiration. Transpiration is like evaporation where water is turned in water vapour by the plants.
- The water that falls on land flows as runoff on the ground. Runoff is the process where water runs over the surface to find its way to the ocean. And due to gravity, it discharges into rivers and other water bodies. The water that flows into streams, lakes, and rivers travels along the surface to reach the sea and finally meet the oceans.
- Some of the water that precipitates does not runoff into the rivers, it either gets absorbed by the plants or gets evaporated. It moves deep into the ground that is known as infiltration. This water seeps down deep and increases the level of the ground water table. This groundwater is mainly used by humans through handpumps, tube wells, and wells.
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Significance of Water Cycle
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The significance of Water Cycle is detailed in the below pointers.
Purification
When water evaporates, all the pollutants in it are left behind. As water undergoes the process of infiltration, the ground purifies it of pollutants and contaminants. The process of evaporation and infiltration benefits every single life on earth by purifying water.
Distribution
Perhaps the most important thing a water cycle does is, it distributes water (not necessarily evenly) all over the earth’s surface. Distribution of water is very crucial as if water was not distributed, gravity would push all the water on the surface into the oceans. The water cycle distributes purified water and feeds it to humans, animals, and plants. Runoffs contribute to rivers, other bodies of freshwater, and ultimately the ocean, maintaining both freshwater and marine life.
Read More: How are clouds formed?
Things to Remember
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- The water cycle is a process where ocean, atmosphere, and land exchange energy.
- This invisible water vapour rises into the atmosphere, where the air is colder, and condenses into clouds.
- Air currents helps move clouds all around the earth. A cloud is formed with tiny water droplets, and those droplets then return to the ocean or land as precipitation as snow.
- The cycling of water influences earth’s climatic conditions and climate change to a great extent.
- Water cycle creates many geographical features present on planet earth like the icebergs, rivers, ice caps of mountains and many more.
Check Also: Acid Rain
Sample Questions
Ques. Why is water important to us? (2 marks)
Ans. The importance of water is pointed below.
- Water helps in regulating body temperature by the process of evaporation and respiration.
- It helps transport all the minerals in plants and animals’ bodies.
Ques. Explain Water cycle in brief. (4 marks)
Ans. The sun’s heat heats water in the oceans. Some of it gets evaporated as vapour into the air. This water vapour rises into the atmosphere, where the air is colder and gets condensed into the clouds. Air currents move these clouds. Water droplets form in clouds and the drops then return to the oceans or land in the form of snow as precipitation. The snow eventually melts back into a liquid and runs off to oceans through lakes or rivers, where it starts the process again.
Ques. What role do plants play in the water cycle? (4 marks)
Ans. Plants play a major role in the whole process of sending water back to the oceans. Plants attract atmospheric moisture in the form of clouds and humidity. The process of condensation on plants provides additional moisture. The groundwater is harnessed by the plants, which is later evapo-transpirated by the plants up to 99%. Hence plants play a major role in the water cycle as well as in atmospheric circulation.
Ques. Define Sea breeze and land breeze? (2 marks)
Ans. Land breeze is blowing breeze from land towards the sea during the night whereas sea breeze is blowing breeze from sea towards land during the day.
Ques. What do you mean by Aquifers? (2 marks)
Ans. Groundwater which is present deep down in the ground beneath the rocks as a reservoir of water is known as aquifers. These aquifers provide about 98% of groundwater. Wells, handpumps, tube wells, etc are used to draw water out of aquifers which recharge naturally through precipitation.
Ques. What is the importance of the water cycle? (2 marks)
Ans. The importance of water is deduced below.
- It regulates the temperature of the surroundings.
- It changes weather and creates rain.
- It helps in conversion of rocks to soil.
- It replenishes, purifies, and circulates water again and again.
Ques. What is transpiration? What are the factors affecting it? (2 marks)
Ans. Some part of water that is absorbed by the plants is later released by them through their leaves into the air by a process called transpiration. Transpiration is affected by the following factors-
- Time of the day
- Humidity
- Windspeed
- Temperature
Ques. Why do rivers originating from the Himalayas do not dry during summer? (2 marks)
Ans. Rivers originating from the Himalayas do not dry up during summers because they get water from the melting snow on the mountains itself. That water helps rivers near the mountains not get dry up easily.
Ques. What are the different forms of precipitation? (2 marks)
Ans. The different forms of precipitation are:
- Snow/Hail
- Rain
- Dew
Ques. Can we use the water in the oceans and seas for drinking purposes? (2 marks)
Ans. No, we cannot use the water in the oceans and seas for drinking purposes as it contains a large amount of salt dissolved in it. The water is used for drinking purposes after the filtration process.
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