vesikierto

Vesikierto, or the water cycle, is the continuous movement of water within the Earth’s system, driven mainly by solar energy and gravity. It connects the oceans, atmosphere, land, and living organisms through a set of physical processes that transport and transform water.

The cycle includes evaporation of water from oceans, rivers and soils, as well as transpiration from plants and sublimation from ice and snow. Water vapor condenses into clouds, which release precipitation as rain, snow or sleet. Water then returns to the surface through infiltration into the soil, runoff across the land, and flow into rivers and lakes, with some seeping deeper to become groundwater. These processes operate across varying timescales, from rapid local evaporation and rainfall to slow groundwater movement that can take centuries.

Major reservoirs in the cycle include the oceans, which contain the largest share of Earth’s water, followed by ice and snow, groundwater, freshwater bodies, soil moisture, and living organisms. Although most water is saline and stored in oceans, the cycle continuously moves freshwater through the atmosphere, land, and biosphere, making it available for ecosystems, agriculture, and human use.

The vesikierto is essential for climate regulation, weather formation, nutrient transport, and sustaining life. Human activities, such as climate change, deforestation, urbanization, and water withdrawals, can alter rainfall patterns, evaporation rates, and groundwater availability, affecting the efficiency and balance of the cycle. Hydrological research seeks to understand and model these processes to manage water resources and assess environmental impacts.