Glossary
Latent Heat of Vaporization
The amount of energy required to convert liquid water into vapor at constant temperature — roughly 2,260 kilojoules per kilogram near 100 °C, and somewhat higher at typical ambient temperatures. This energy is absorbed from the surroundings as water evaporates.
Because evaporation absorbs latent heat, it cools the water surface and the surrounding air. This link between energy and mass loss is what allows energy-budget calculations to convert available energy into an evaporation rate.