Describe water cycle. Briefly explain the major processes involved in water cycle?
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| Water Cycle |
The
water cycle, also known as the hydrologic cycle, is the continuous process
through which water circulates and moves between various reservoirs on Earth.
It involves the evaporation of water from the Earth's surface, the condensation
of water vapor into clouds, precipitation, and the flow of water through rivers
and underground aquifers. The water cycle is a crucial natural process that
sustains life and maintains a balance of water on our planet. It can be
summarized in the following steps:
1. Evaporation:
The water cycle begins with evaporation, where heat from the Sun causes water
to change from a liquid state (in oceans, lakes, rivers, and other water
bodies) into water vapor or gas. This process mainly occurs in oceans, but it
can also happen from moist soil and vegetation surfaces.
2. Condensation:
As the water vapor rises into the atmosphere, it cools down and condenses back
into tiny water droplets, forming clouds. This occurs due to the cooling effect
of the upper atmosphere or when the air containing water vapor comes into
contact with cooler surfaces like mountains.
3. Precipitation: When the water droplets in the clouds become
large and heavy enough, they fall back to the Earth's surface as precipitation.
This can take the form of rain, snow, sleet, or hail, depending on the
atmospheric conditions.
4. Infiltration
and Runoff: Once precipitation reaches the Earth's surface, it
can take two main paths. Some of it may infiltrate the soil, gradually seeping
into the ground to become groundwater. This water is then available for
vegetation and can eventually discharge into rivers, lakes, or oceans. The rest
of the precipitation can flow over the land surface, becoming runoff, and
finding its way into rivers, streams, and other water bodies.
5. Transportation: The water that reaches rivers and streams is
transported back to the oceans, lakes, or other water bodies. This movement is
a crucial part of the water cycle, ensuring the distribution of freshwater
around the planet.
6. Sublimation:
In some instances, water can transition directly from a solid (ice or snow) to
water vapor without going through the liquid state. This process is known as
sublimation.
7. Evapotranspiration: Another significant process contributing to
the water cycle is evapotranspiration. This is the combined loss of water
through evaporation from the soil and transpiration from plants. Plants absorb
water through their roots and release it into the atmosphere through tiny
openings called stomata in their leaves.
The
water cycle is a continuous and dynamic process, and the amount of water stored
in different reservoirs and the rate of movement between them can vary
regionally and seasonally. This natural process is essential for sustaining
life, supporting ecosystems, and maintaining a stable climate on Earth. Human
activities, such as deforestation, urbanization, and pollution, can influence
the water cycle and have significant impacts on water availability and quality.