évaporation

Évaporation, or evaporation in English, is the process by which a liquid changes to a gas at temperatures below its boiling point. It occurs at the liquid's surface when molecules gain enough energy to overcome intermolecular forces and escape into the surrounding air. Evaporation can happen for any liquid, and it continues until either all the liquid is gone or the vapor is in equilibrium with the liquid (saturation).

The rate of evaporation depends on several factors: temperature, surface area, humidity, wind speed, and the vapor-pressure deficit between the liquid surface and the surrounding air. Higher temperatures increase molecular energy; larger surface area allows more molecules to escape; lower ambient humidity and greater air movement remove vapor more quickly, maintaining a driving gradient.

Distinctions: evaporation is a surface phenomenon and can occur below the boiling point; boiling is a bulk process in which vapor bubbles form inside the liquid when its vapour pressure equals ambient pressure at a given temperature.

Applications and relevance: evaporation is central to the hydrological cycle, climate, and many industrial processes. It is used in drying foods and textiles, concentrating liquids, and producing salt in evaporative ponds. In meteorology, evaporation from land and water surfaces is a key component of evapotranspiration, which also includes plant transpiration.

Measurement and estimation: methods include pan evaporation measurements, lysimeters, and satellite-based estimates; evaporation rates are influenced by weather patterns, season, and geographic location.