Evapotranspiration

Evapotranspiration describes the way water moves from land up into the atmosphere through soil evaporation and transpiration by plants.

Evapotranspiration is the sum of plant transpiration and evaporation (Public Domain)

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As the sun heats the Earth’s surface, the water stored in soil evaporates, rising up into the atmosphere. Sunlight also increases the surface temperatures of lakes and oceans, causing some of that water to evaporate.


Transpiration refers to the way water is lost as plants open pores, called stomata, found on the underside of leaves, and on stems and flowers. These cells open to allow for the gas exchange necessary for photosynthesis. A large, well-watered tree can lose 100 gallons of water each day in hot weather through evapotranspiration!


Hot weather increases a plant’s need for water. At the same time, higher temperatures increase evaporation of the water found in soil. The combined affect is the reason why you need to water your plants more often and more deeply in summer. 

​Now you know.