Evaporation can be defined as the process where liquid water is transformed into a gaseous state. Evaporation can only occur when water is available. The evaporation process requires large amounts of energy. For example, the evaporation of one gram of water requires 600 calories of heat energy .
Transpiration is the process of water loss from plants through stomata .
Stomata are small openings found on the underside of leaves that are connected to vascular plant tissues. In most plants, transpiration is a passive process largely controlled by the humidity of the atmospheric and the moisture content of the soil. Transpiration also transports nutrients from the soil into the roots and carries them to the various cells of the plant and is used to keep tissues from becoming overheated. Some dry environment plants do have the ability to open and close their stomata. This adaptation is necessary to limit the loss of water from plant tissues.