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Water cycle, also called hydrologic cycle, cycle that involves the continuous circulation of water in the Earth-Atmosphere system. Of the many processes involved in the water cycle, the most important are Evaporation, Transpiration, condensation, Precipitation, and runoff. Although the total amount of water within the cycle remains essentially constant, its distribution among the various processes is continually changing.
Evaporation, one of the major processes in the cycle, is the transfer of water from the surface of the Earth to the atmosphere. By evaporation, water in the liquid state is transferred to the gaseous, or vapour, state. This transfer occurs when some Molecules in a water mass have attained sufficient kinetic energy to eject themselves from the water surface. The main factors affecting evaporation are temperature, humidity, wind speed, and solar radiation. The direct measurement of evaporation, though desirable, is difficult and possible only at point locations. The principal source of water vapour is the Oceans, but evaporation also occurs in soils, snow, and ice. Evaporation from snow and ice, the direct conversion from solid to vapour, is known as sublimation. Transpiration is the evaporation of water through minute pores, or stomata, in the leaves of Plants. For practical purposes, transpiration and the evaporation from all water, soils, snow, ice, vegetation, and other surfaces are lumped together and called evapotranspiration, or total evaporation.
Water vapour is the primary form of atmospheric moisture. Although its storage in the atmosphere is comparatively small, water vapour is extremely important in forming the moisture supply for dew, frost, fog, clouds, and precipitation. Practically all water vapour in the atmosphere is confined to the Troposphere (the region below 6 to 8 miles [10 to 13 km] altitude).
The transition process from the vapour state to the liquid state is called condensation. Condensation may take place as soon as the air contains more water vapour than it can receive from a free water surface through evaporation at the prevailing temperature. This condition occurs as the consequence of either cooling or the mixing of air masses of different temperatures. By condensation, water vapour in the atmosphere is released to form precipitation.
Precipitation that falls to the Earth is distributed in four main ways: some is returned to the atmosphere by evaporation, some may be intercepted by vegetation and then evaporated from the surface of leaves, some percolates into the Soil by infiltration, and the remainder flows directly as surface runoff into the sea. Some of the infiltrated precipitation may later percolate into streams as groundwater runoff. Direct measurement of runoff is made by stream gauges and plotted against time on hydrographs.
Most groundwater is derived from precipitation that has percolated through the soil. Groundwater flow rates, compared with those of surface water, are very slow and variable, ranging from a few millimetres to a few metres a day. Groundwater movement is studied by tracer techniques and remote sensing.
Ice also plays a role in the water cycle. Ice and snow on the Earth’s surface occur in various forms such as frost, sea ice, and glacier ice. When soil moisture freezes, ice also occurs beneath the Earth’s surface, forming permafrost in Tundra climates. About 18,000 years ago Glaciers and ice caps covered approximately one-third of the Earth’s land surface. Today about 12 percent of the land surface remains covered by ice masses.
Importance of hydrological cycle
The hydrologic cycle is important because it is how water reaches plants, animals and us! Besides providing people, animals and plants with water, it also moves things like nutrients, pathogens and sediment in and out of aquatic Ecosystems.
One of the ways that water moves through the cycle is through its ability to permeate, or soak, into the soil. There are four key areas that impact that part of the cycle:
- changes in the ability of soil to soak up water through increases of impervious surfaces, like roads and buildings, and removal of forest cover;
- water withdrawals or impoundments (such as through wells or Dams)
- filling depressional wetlands; and
- altering stream flows and beds.
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The hydrological cycle is the continuous movement of water on, above and below the Earth’s surface. It is powered by the sun’s energy and is essential for life on Earth.
The main subtopics of the hydrological cycle are:
- Evaporation: The process by which water changes from a liquid to a gas or vapor.
- Condensation: The process by which water vapor in the air changes into liquid water.
- Precipitation: The process by which water falls from the sky as rain, snow, sleet or hail.
- Infiltration: The process by which water on the surface of the Earth soaks into the ground.
- Percolation: The movement of water through the soil and rocks.
- Runoff: The movement of water over the surface of the Earth.
- Storage: The process by which water is stored in the atmosphere, on the surface of the Earth, in the soil, in the rocks and in the oceans.
The hydrological cycle is a complex system that is essential for life on Earth. It provides us with water for drinking, bathing, cooking and Irrigation. It also helps to regulate the Earth’s Climate.
Evaporation is the process by which water changes from a liquid to a gas or vapor. It is the primary way that water moves from the Earth’s surface to the atmosphere. Evaporation occurs when water molecules at the surface of a liquid absorb energy from the sun and escape into the air. The rate of evaporation depends on the temperature of the water, the amount of wind and the humidity of the air.
Condensation is the process by which water vapor in the air changes into liquid water. It occurs when water vapor molecules collide with other molecules and lose energy. Condensation can occur on the surface of the Earth, such as on leaves or windows, or it can occur in the atmosphere, such as in clouds.
Precipitation is the process by which water falls from the sky as rain, snow, sleet or hail. It is the primary way that water returns to the Earth’s surface from the atmosphere. Precipitation occurs when water vapor in the air condenses and falls to the ground. The type of precipitation that falls depends on the temperature of the air.
Infiltration is the process by which water on the surface of the Earth soaks into the ground. It occurs when water flows through cracks and pores in the soil. The rate of infiltration depends on the type of soil, the amount of rainfall and the slope of the land.
Percolation is the movement of water through the soil and rocks. It occurs when water that has infiltrated the soil moves downward due to gravity. The rate of percolation depends on the type of soil, the amount of rainfall and the depth of the water table.
Runoff is the movement of water over the surface of the Earth. It occurs when water flows over the land due to gravity. The rate of runoff depends on the amount of rainfall, the slope of the land and the type of land cover.
Storage is the process by which water is stored in the atmosphere, on the surface of the Earth, in the soil, in the rocks and in the oceans. The amount of water that is stored in each of these reservoirs varies depending on the time of year and the weather conditions.
The hydrological cycle is a complex system that is essential for life on Earth. It provides us with water for drinking, bathing, cooking and irrigation. It also helps to regulate the Earth’s climate.
What is the water cycle?
The water cycle is the continuous movement of water on, above and below the Earth’s surface. It is powered by the sun’s energy and is essential for life on Earth.
How does the water cycle work?
The water cycle begins with the sun’s energy evaporating water from the Earth’s surface. This water vapor rises into the atmosphere and cools, condensing into clouds. The clouds release the water back to the Earth as precipitation, such as rain or snow. The water then flows back into the oceans, lakes, rivers, and groundwater, or it is absorbed by plants.
What are the stages of the water cycle?
The water cycle has four main stages: evaporation, condensation, precipitation, and collection.
- Evaporation is the process by which water changes from a liquid to a gas or vapor.
- Condensation is the process by which water vapor in the air changes into liquid water.
- Precipitation is the process by which water falls from the sky as rain, snow, sleet, or hail.
- Collection is the process by which water collects on the Earth’s surface in oceans, lakes, rivers, and groundwater.
What are the benefits of the water cycle?
The water cycle is essential for life on Earth. It provides us with fresh water to drink, water for crops, and water for hydroelectric power. The water cycle also helps to regulate the Earth’s temperature and climate.
What are the challenges of the water cycle?
The water cycle is facing a number of challenges, including Climate Change, pollution, and water scarcity. Climate change is causing the Earth’s temperature to rise, which is leading to more evaporation and more extreme weather events, such as droughts and floods. Pollution is contaminating water supplies and making it unsafe to drink or use for irrigation. Water scarcity is a growing problem in many parts of the world, as demand for water increases and supplies become limited.
What can we do to protect the water cycle?
We can protect the water cycle by reducing our reliance on fossil fuels, which contribute to climate change. We can also reduce pollution by recycling and conserving water. We can also support sustainable water management practices, such as rainwater harvesting and greywater recycling.
The Earth’s water cycle is a closed system. This means that:
(a) Water can only be found on the Earth’s surface.
(b) Water can only be found in the atmosphere.
(c) Water can only be found in the oceans.
(d) Water can move between the Earth’s surface, the atmosphere, and the oceans.The main Source Of Energy for the Earth’s water cycle is:
(a) The sun.
(b) The moon.
(c) The Earth’s rotation.
(d) The Earth’s gravity.The process of water evaporating from the Earth’s surface is called:
(a) Condensation.
(b) Precipitation.
(c) Evaporation.
(d) Transpiration.The process of water condensing into clouds is called:
(a) Condensation.
(b) Precipitation.
(c) Evaporation.
(d) Transpiration.The process of water falling from the sky as rain, snow, sleet, or hail is called:
(a) Condensation.
(b) Precipitation.
(c) Evaporation.
(d) Transpiration.The process of water soaking into the ground is called:
(a) Infiltration.
(b) Percolation.
(c) Runoff.
(d) Evaporation.The process of water flowing over the Earth’s surface is called:
(a) Infiltration.
(b) Percolation.
(c) Runoff.
(d) Evaporation.The process of water plants taking in water from the soil is called:
(a) Infiltration.
(b) Percolation.
(c) Runoff.
(d) Transpiration.The process of water evaporating from plants is called:
(a) Infiltration.
(b) Percolation.
(c) Runoff.
(d) Transpiration.The Earth’s water cycle is important because it:
(a) Provides us with fresh water.
(b) Regulates the Earth’s temperature.
(c) Distributes nutrients around the globe.
(d) All of the above.