Evaporation
Evaporation is the slow escape of high-energy molecules from the surface of a liquid at any temperature below its boiling point.
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Evaporation
High-energy surface particles escape; remaining liquid cools.
Surface process
In a liquid, particles at the surface have a range of kinetic energies. Some high-energy particles can overcome attractive forces and escape into the air as gas. This process, which happens at the surface and at all temperatures below the boiling point, is called evaporation.
Cooling effect
Because the highest-energy particles leave, the average kinetic energy of the remaining particles decreases, which lowers the liquid’s temperature. This is why evaporation causes cooling (e.g. sweating cools the body).
Why do we feel cool when sweat evaporates from our skin on a windy day?