Hello fellow researchers. As you may be aware, the equations proposed by Penman and Penman-Monteith have been successfully used for predicting the rates of moisture losses (E or ET) from a bare water surface and a crop respectively.
I was recalculating E for some certain conditions and the results did not make sense.
For example: Consider a wind speed of 20 m/s, ambient air temperature at 20 degrees, water surface temperature at 21 degrees, and net radiation of 180 Wm^-2. The penman equation gives a value of 17 mm/day (equivalent to 420 Wm^-2 of latent heat) for the evaporation rate.
In this case the latent heat loss is much higher than the net radiation input. How is this possible?
Physically, what must happen is this - at this wind speed, the water surface temperature has to go below the air temperature such that the ambient air gives some energy convectively as well along the net radiation to support the latent heat loss.
The question here is, therefore, what set of parameters determine the violation of the Penman equation?
Thank you, in advance, for your suggestions.
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