Why is the water cycle important? There are many reasons. Read on to learn more.
What is the water cycle?
The amount of water on Earth has been roughly the same for billions of years, but it is constantly in motion, moving around the Earth and changing states, from liquid to gas to solid and back again. The water cycle is a description of where the water is, where it goes, and how it moves from place to place.
The water cycle is a description of where the water on earth is, where it goes, and how it moves from place to place.
There are a variety of water reservoirs on Earth that hold large amounts of water – ice (snow caps and glaciers), fresh water (lakes and rivers), saline water (oceans and seas) and atmospheric water (clouds and water vapor). The water on Earth moves between these reservoirs constantly, using the processes of evaporation, condensation, precipitation, percolation, and runoff.
Large bodies of water are heated by the sun and water molecules at the surface gain enough energy to break free from the attractive forces that normally hold them together. The molecules evaporate, rising into the atmosphere as vapor. At the same time, water vapor is given off by trees and plants in a process known as transpiration.
Once in the atmosphere, the water vapor cools and condenses into liquid water or solid ice, hail, or snow. These water particles then accumulate and form clouds.
Clouds are moved around the Earth by air currents, and the water particles precipitate back to the Earth as rain, snow, hail, sleet, drizzle, or fog. Precipitation patterns are linked to land formations – for example, as clouds rise over mountains, they cool and the water vapor inside turns to water, becoming so heavy that the water is released.
Precipitation falls mainly on the oceans, but also on land, where it is either captured by trees and plants or it hits the ground. Water that hits the ground will either move down through cracks in rocks and soil into the water table, or it will run overland into nearly lakes, streams, and rivers. The water in lakes, streams, and rivers flow to the surrounding seas and oceans to start the cycle all over again.
In cold regions in the winter, most of the precipitation is stored as snow or ice on the ground until the spring, when large volumes of water melt suddenly, resulting in heavy runoff.
Why is the water cycle important?
Water is essential for most ecosystems on Earth.
Evaporation purifies salt water, allowing the resulting precipitation to provide the land and its organisms with fresh water. When water evaporates, it cools the environment by taking in energy.
Conversely, when water condenses, it releases energy, which warms the environment. In this way, the water cycle is linked to energy exchange and variations in temperature. It also participates in the formation of geological structures found on Earth, using erosion and sedimentation.
Ultimately, the movement of water through the water cycle is tied to climate, energy, temperature, geology, and sustainable life on Earth.
The water cycle is important because every living organism needs water to survive.