Evaporation describes the process of a liquid changing to a gas. Usually, the surface parts of a pool of liquid vaporize into a vapor or gas first. Evaporation occurs in both cold and warm liquids.
Warmer liquids evaporate quicker than cooler liquids. This is due to the fact that adding more energy to a liquid causes some of the molecules to become energized enough to release the liquid into the air. An example of this is when a pot of water boils on a stove. Once the water gets hot enough, liquid water converts and changes phases into a gas; if enough of the water is evaporating, it becomes visible as steam. Cold water can also evaporate.
Molecules in a liquid actually have different levels of energy. When this happens, some of the water converts into gas; that is why wind can increase evaporation rates. Evaporation also removes heat from a system, which is why when water evaporates on someone’s skin, they then feel cooler.
Evaporation is the mechanism that drives the water cycle. When water evaporates from the oceans, it rises into the atmosphere and eventually falls again as rain, which is then fresh water since the evaporating water loses all of the salt from the oceans.