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Question 5.4: Assuming a cloudless sky, estimate the downward long-wave ir...

Assuming a cloudless sky, estimate the downward long-wave irradiance and the atmospheric emissivity at the ground when the air temperature is 25 ºC. If the sky was covered by 50% cloud, estimate the long-wave irradiance in this case. Why are these values only climatological approximations?

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L_{d} = 356 \; W\; m^{-2} ; \varepsilon _{a} =0.79.
When c= 0.5,\varepsilon _{a} \left(c\right) = 0.88, and L_{d} \left(c\right) = 0.88 \times 448 = 393\; W\; m^{-2}.

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