Glossary
Evaporation
The process by which liquid water molecules with enough kinetic energy escape from a water surface into unsaturated air, becoming water vapor. From open water bodies it is driven mainly by the vapor-pressure deficit between the surface and the air.
Evaporation is a surface phenomenon, so loss scales with surface area rather than depth — depth only changes how long a water body lasts, not the rate per unit area. The six dominant factors are air temperature, water temperature, relative humidity, wind speed (and fetch), surface area, and solar radiation. Evaporation continues at night, often accounting for 25–40% of the 24-hour total in arid climates.