Vedenkiertoliikkeessä

Vedenkiertoliikkeessä, also known as the water cycle, describes the continuous movement of water on, above, and below the surface of the Earth. This fundamental process is driven by solar energy and gravity, ensuring the availability of freshwater.

The cycle begins with evaporation, where water from oceans, lakes, rivers, and even soil turns into vapor and rises into the atmosphere. Plants also contribute through transpiration, releasing water vapor from their leaves. As this moist air ascends, it cools, leading to condensation. Water vapor transforms into tiny water droplets or ice crystals, forming clouds.

When these droplets or crystals become too heavy, precipitation occurs. Water falls back to Earth in various forms, including rain, snow, sleet, or hail. Once on the surface, water can follow several paths. It might flow over the land as surface runoff, eventually reaching rivers, lakes, and oceans. Alternatively, it can infiltrate the ground, becoming groundwater. Groundwater can move slowly through the soil and rock layers, sometimes resurfacing in springs or seeping into bodies of water.

A portion of the water that falls as precipitation is stored in glaciers and ice caps. Over time, this ice can melt, contributing to runoff. The water cycle is a closed system, meaning the total amount of water on Earth remains relatively constant, though its form and location change. This perpetual motion is crucial for sustaining life and shaping Earth's diverse landscapes.