Penman Equation - Some Useful Relationships

Some Useful Relationships

δe = (e_s - e_a) = (1-relative humidity)e_s

e_s = saturated vapor pressure of air, as is found inside plant stoma.

e_a = vapor pressure of free flowing air.

e_s, mmHg = exp(21.07-5336/T_a), approximation by Merva, 1975

Therefore, mmHg/K

T_a = air temperature in kelvins