Evaporation from hot water. (Source: © toa555 / stock.adobe.com)

The process by which the surface of a liquid changes into a gas. It can occur at temperatures below the boiling point of the liquid. Evaporation removes energy from its surroundings, and so the liquid that is evaporating is cooled. The larger the surface area of the evaporating liquid, the faster the evaporation.

In the tertial circuit of thermal power plants, the cooling water is sprayed out in tiny droplets to maximize their surface area. Subsequent evaporation from the surface of the droplets cools the water sufficiently. The excess heat is then carried away by steam into the atmosphere.