Energy & Green Tech

A new low-cost solar technology for environmental cooling

Space cooling and heating is a common need in most inhabited areas. In Europe, the energy consumed for air conditioning is rising, and the situation could get worse in the near future due to the temperature increase in different ...

Energy & Green Tech

Future maps: We have the blueprint for livable, low-carbon cities

Over the past seven years more than 100 research projects at the Co-operative Research center for Low Carbon Living, in collaboration with industry across Australia, have pondered a very big question: How do we build future ...


Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid.

On average, the molecules in a glass of water do not have enough heat energy to escape from the liquid. With sufficient heat, the liquid would turn into vapor quickly (see boiling point). When the molecules collide, they transfer energy to each other in varying degrees, based on how they collide. Sometimes the transfer is so one-sided for a molecule near the surface that it ends up with enough energy to 'escape' (evaporate).

Liquids that do not evaporate visibly at a given temperature in a given gas (e.g., cooking oil at room temperature) have molecules that do not tend to transfer energy to each other in a pattern sufficient to frequently give a molecule the heat energy necessary to turn into vapor. However, these liquids are evaporating. It is just that the process is much slower and thus significantly less visible.

Evaporation is an essential part of the water cycle. Solar energy drives evaporation of water from oceans, lakes, moisture in the soil, and other sources of water. In hydrology, evaporation and transpiration (which involves evaporation within plant stomata) are collectively termed evapotranspiration. Evaporation of water occurs when the surface of the liquid is exposed, allowing molecules to escape and form water vapor, this vapor can then rise up and form clouds.

This text uses material from Wikipedia, licensed under CC BY-SA