Evaporation vs Transpiration
Evaporation and transpiration are two different mechanisms through which removal of water from the surface of the earth into the atmosphere takes place. Evaporation and transpiration are similar in the sense that both result in loss of water that is released in the atmosphere. However there are differences between the two mechanisms that need to be highlighted. This article will describe the features of both the processes to make a clearer understanding.
Evaporation
It is the process in which water is changed from its liquid state into its gaseous state called water vapor. Energy is required to change water into water vapor. Evaporation takes place only on the surface of water which is different from boiling which takes place on the entire mass of water. We know that water molecules keep colliding with each other thus increasing their energy. Sometimes this transfer of energy from one molecule to another is so one sided that those molecules that are near the surface get released in the atmosphere.
Evaporation is an integral part of water cycle. Sun’s heat causes evaporation of water from water bodies into the atmosphere.
Transpiration
This is the process of loss of water from plants through stomata which are small openings on the underside of leaves connected to vascular plant tissues. This is a process that is dependent upon moisture content of the soil as well as relative humidity of the atmosphere. Transpiration also helps in carrying nutrients from the soil into the roots and then into various plant cells to keep tissues from getting overheated. Some plants have the ability to close and open the openings in their stomata. This limits the loss of water from stomata. This adaptation helps the plants to survive under extreme hot conditions.
The sum of water loss from the earth is the sum of effects of evaporation and transpiration and is called Evapotranspiration (ET).
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Summary • Evaporation and transpiration are two distinct mechanisms for loss of water into the atmosphere. • Evaporation takes place from the surface of water bodies when water gets transformed into its gaseous state called water vapor. On the other hand transpiration is the process of loss of water from plants from small opening on the underside of leaves called stomata. • The total loss of water through both evaporation and transpiration has been given a new term called Evapotranspiration
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