O water cycle, also known as hydrological cycle, refers to the continuous movement that water makes through the physical environment and the living beings of the ecosystem, passing through the atmosphere, hydrosphere, lithosphere and biosphere. It is, therefore, an important cycle biogeochemical that makes this indispensable natural resource constantly in the environment.
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→ Biogeochemical cycles
We give the name of biogeochemical cycles to those cycles in which a certain substance passes from the abiotic environment (air, water, soil) to living beings and passes from these back to the environment. Therefore, biogeochemical cycles are processes in which elements are cycling. O water cycle stands out as one of the main biogeochemical cycles, since this substance is found in absolutely all living beings and participates in their metabolic processes, its cycling in the environment is fundamental.
→ The water
Water is found in the environment in solid, liquid and water vapor forms.
THE Water is a substance formed by two hydrogen atoms and one oxygen atom, where H2Its chemical formula. Found mainly in the liquid state, it is the most abundant substance in the earth's crust. It is estimated that 70% of the planet is covered by water, and the vast majority of it is in the oceans. After the oceans, the second largest water reservoir on the planet are the glaciers. On the continents, this substance is found mainly in groundwater. We realize, therefore, that water is a chemical compound that can be found, simultaneously, in solid (glaciers), liquid (rivers, seas and oceans) and gaseous (water vapour) forms.
Mind Map: Water Cycle
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→ Steps in the water cycle
The water cycle, also called the hydrological cycle, occurs through changes in the States physicists and the movement of water by living beings and the environment. This cycle depends directly on solar energy, the Earth's rotational movements and even gravity.
Note above a scheme of the water cycle.
The Sun is responsible for providing energy for the cycle to happen. Its light causes the evaporation of water present on the earth's surface. In some places, however, snow and ice sublimes from solid to vapor, skipping the melting (solid to liquid) and evaporation phases.
The water, now in a gaseous state, rises to higher layers of the atmosphere, where the temperature is lower. Upon reaching a certain altitude, this substance changes from a vapor state to a liquid (condensation) and form the clouds, which are actually a lot of water droplets. In cold places, these droplets can solidify and give rise to snow or hail.
When starting the rain, process also called precipitation, water begins to return to the earth's surface and is directly influenced by gravity. At that time, it can reach rivers, lakes and oceans, infiltrate the soil and rocks, or it can be prevented from returning to the earth's surface by vegetation.
Rain ensures that water returns to the earth's surface.
Living beings play a decisive role in the water cycle. As all organisms have this substance in their bodies, water also flows through food chains. In addition, plant roots absorb water, and animals obtain this substance by drinking it or taking it from food.
Animals lose water through processes such as the elimination of urine and feces, breathing and perspiration. Plants, on the other hand, lose water through transpiration, a process in which water vapor is released by the stomata (structures present in the plant epidermis that act in gas exchange), and byguttation, process in which the eliminated water is in a liquid state. In addition, part of the water that becomes incorporated in these beings is eliminated during the process of decomposition.
According to the United States Geological Survey (USGS), we can identify 16 important parts of the water cycle:
storage of water in the oceans (largest water reservoir on the planet);
evaporation (change of water from a liquid to a gaseous state);
evapotranspiration (loss of water by soil and plants);
sublimation (transition of ice and snow to the vapor state without first passing through the liquid state);
water in the atmosphere;
condensation (passage of water from vapor to liquid);
precipitation (rain);
storage of water in the form of ice and snow;
snowmelt stream to rivers;
surface current (water on the ground surface that goes into rivers);
river current (water that flows into rivers, streams or streams);
storage of fresh water on the Earth's surface;
infiltration;
storage in the water table;
groundwater discharge (movement of water out of the ground);
sources (place where groundwater is discharged to the soil surface).
It is important to say that the water cycle varies depending on where it occurs. Factors such as vegetation cover, altitude, temperature and soil type, for example, directly affect the amount of water involved in the process and the speed of the cycle. Thus, the 16 points mentioned above happen on the planet as a whole and not just in specific areas.
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→ Importance of the water cycle
Like other living things, humans need water for their bodies to function.
The water cycle is important because ensures that this substance constantly circulates through the environment, passing through living organisms and the physical environment. As water circulates in the environment, it can supply the needs of living beings, who need this substance daily for the proper functioning of their organism. In addition, the permanence of water in the environment is important for some activities carried out by human beings, since it is fundamental for the energy generation, development of agricultural and agricultural production, various industrial activities and some daily tasks, such as washing clothes and dishware.
However, it is important to highlight that, although the water cycle ensures that this substance constantly circulates in the medium, this does not guarantee that there will be no water shortage. This is due to the fact that the water cycle is complex and it can be affected by a variety of factors, such as wind, which can cause water that has evaporated in one area to be precipitated in others.
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→ water cycle summary
The water cycle is a biogeochemical cycle that ensures the water circulates by the physical environment and by living beings. This process depends on sunlight, which ensures that the water evaporates, starting the cycle. Water vapor rises to higher layers of the atmosphere and condenses, forming clouds, which are small droplets of liquid water. When these clouds become charged, precipitation (rain) occurs, which can occur in liquid form or in the form of hail and snow. The rainwater, then, returns to Earth, and can follow different paths, such as returning to lakes and rivers or infiltrating the soil.
By Ma. Vanessa dos Santos
