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T = 15oC
Qn = 600 cal/cm2/d
v2 = 150 km/d
RH = 70%
The saturation vapor pressure at the overlying air temperature of
15oC is:
eo = 17.04 mb
For the given climatic conditions,
the mass-transfer evaporation rate according to Dunne is:
Ea = (0.013 + 0.00016 × 150) × 17.04 × [(100 - 70)/100] = 0.189 cm/d
The water density and heat of vaporization is:
ρ = 0.999 gr/cm3, and
λ = 588.9 cal/gr.
The evaporation rate due to net radiation is:
En = (600 cal/cm2/d) / (0.999 gr/cm3 × 588.9 cal/gr) = 1.02 cm/d
Penman's ratio (Table 2-4):
α = 1.66
The evaporation rate by the Penman formula is:
E = (1.66 × 1.02 + 0.189) / (1.66 + 1) = 0.71 cm/d. ANSWER.
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