CONCEPTS

What is the water cycle?

We explain what the water cycle is and its stages: evaporation, condensation, precipitation and infiltration. Water cycle images.

  1. What is the water cycle?

It is known as the water cycle or the hydrological cycle to one of the most important biochemical circuits on planet Earth , in which water undergoes a series of transformations and displacements resulting from physical-chemical reactions, going through the three states of matter : Liquid , solid and gaseous.

It is important to know that water is one of the most abundant substances on the planet: 71% of the earth’s surface is covered by liquid water , of which 96.5% is salt water from the oceans . Of the remaining fresh water, 69% is frozen in the polar caps; At the same time, between 1% and 4% of the gases in the atmosphere correspond to water vapor.

Therefore, the water cycle is vital for the maintenance and stability of our planet , not only for life as we know it, unthinkable without access to this vital liquid , but also for the regularity of the climate , of world temperature and other conditions that determine planetary reality.

Various environmental factors and intra and extra planetary forces, such as wind and sunlight, respectively, are involved in this hydrological cycle. Like any cycle, it does not really start at any given point , but it is a continuity of processes that are repeated successively, mobilizing amounts of chemical energy .

If this cycle stopped for some reason, the effects would be catastrophic: hot regions would take much longer to cool, water would stagnate in the oceans and lakes and life would suffer the consequences.

  1. Stages of the water cycle

water cycle
Image:  https://es.khanacademy.org/

The water cycle consists of the following successive and simultaneous stages, which are repeated incessantly and interconnected with each other:

  • Evaporation . Considering that about 96% of the planet’s water is stored in the oceans, these can be taken as a starting point for the study of the hydrological cycle. Thus, this would begin with theevaporation processes that convertthe surface of the liquid water of the oceansinto gas , thanks to the action of sunlight and the daily warming of the Earth. The oceans provide 90% of the water vapor in the atmosphere . The lakes and rivers contribute a smaller percentage; and another minor still the glaciers and snows that, being in very cold climates to become water, sublimate instead of evaporating (they pass from solid to gaseous directly).
  • Condensing . The water in the atmosphere travels huge distances, spreading through the winds and cooling remote regions of the ocean. Up there, the lower temperature allows water vapor to condense, gradually recovering its liquid form, to form increasingly dark clouds as they contain more and more drops of water.
  • Precipitation . When the water droplets contained in the clouds are already large and heavy enough, they break their equilibrium state and rains or rainfall occur. Water usually falls in liquid form, but in certain regions and climatic conditions it can be done in a more or less solid form, such as snow, frost or hail.
  • Melt and drained water . In the specific case of water that falls on land, far from rivers, lakes or oceans, or from which it falls like snow or hail on the summit of mountains and other icy and dry places, the return of the liquid to the seas is Produces through other methods . Thus, the discharge of filtered water to the underground layers of the earth, runoff due to gravity and topography , or the melting of ice in warm seasons, as occurs in the poles and in the icy continental regions, return the water to its initial cycle point.

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