Evaporation is the process of molecular diffusion of molecules from a liquid surface to an adjacent gaseous phase. The other type of vaporization is boiling, which involves the change of a liquid to a gas at or above atmospheric pressure without the presence of external energy.

Evaporation and boiling are endothermic processes that happen at the interface between two phases with different temperatures, typically by aid of thermal energy. A vapor that cools the surroundings during its formation is sometimes referred to as an evaporation, which can be made visible by fog or mist.

The opposite process to evaporation is condensation. In addition to the loss of heat, there is also some potential energy released when water evaporates from a body, often due to molecular interactions with air or other nearby matter.

When water evaporates under adiabatic conditions (no transfer of heat), it generally becomes colder as it does so (a phenomenon known as evaporative cooling). This was first discovered by Michael Faraday in 1843 and may be described mathematically as follows.

Last modified: October 4, 2022