What is the Difference Between Actual Evapotranspiration and Potential Evapotranspiration?

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The difference between actual evapotranspiration and potential evapotranspiration lies in the amount of water involved in each process and the factors that limit them. Here are the key differences:

  • Actual Evapotranspiration (AE): This refers to the actual amount of water that is evaporated through the surface and lost from a surface due to evaporation and transpiration. It is limited by the amount of water available, such as precipitation and soil moisture.
  • Potential Evapotranspiration (PE): This is a measure of the ability of the atmosphere to remove water from the surface through the processes of evaporation and transpiration. It represents the maximum amount of water that would be evapotranspired if enough water were available.

In summary, actual evapotranspiration is the amount of water that is actually removed from the surface, while potential evapotranspiration is the maximum amount of water that could be removed if there were no limitations on water availability. Potential evapotranspiration generally takes a higher value than actual evapotranspiration, but when there is an ample amount of water, actual evapotranspiration can be equal to potential evapotranspiration.

Comparative Table: Actual Evapotranspiration vs Potential Evapotranspiration

The difference between actual evapotranspiration and potential evapotranspiration lies in the factors that control them. Here is a comparison table of the two:

Feature Actual Evapotranspiration (AET) Potential Evapotranspiration (PET)
Definition The quantity of water that is actually removed from a surface by the processes of evaporation and transpiration. A representation of the atmospheric demand for evapotranspiration, which is the sum of evaporation and transpiration. It is driven by energy from sunlight and wind.
Control No control in the water supply. Utilizes 80% of its energy from the sun and takes energy from the wind.
Value Actual evapotranspiration is typically lower than potential evapotranspiration. Potential evapotranspiration takes a higher value than actual evapotranspiration.
Calculating Crop Water Need By subtracting actual evapotranspiration from potential evapotranspiration. -

In summary, actual evapotranspiration is the amount of water that is actually removed from a surface due to the processes of evaporation and transpiration, while potential evapotranspiration represents the atmospheric demand for evapotranspiration, driven by energy from sunlight and wind. Actual evapotranspiration is typically lower than potential evapotranspiration, and crop water need can be calculated by subtracting actual evapotranspiration from potential evapotranspiration.