Evaporation

Evaporation is the change of a liquid into gas that happens at the surface of a liquid, when molecules near the surface gain enough kinetic energy to overcome the forces holding them in the liquid and escape into the surrounding air. Because the fastest-moving molecules escape first, the average energy left behind drops, cooling the remaining liquid, a process called evaporative cooling. Solar energy drives evaporation from oceans, lakes and soil moisture, feeding water vapor into the atmosphere where it later cools, condenses into clouds and falls again as precipitation; in hydrology evaporation is combined with the water lost from plants, transpiration, into the single measure evapotranspiration.