Describes why Middleton's simple expression for the visible and infrared extinction coefficient due to rain is incorrect. By improperly using Stokes' law to obtain the terminal velocity of a raindrop through air, Middleton underestimated the extinction coefficient due to rain by nearly a factor of ten. A revised expression for the coefficient is derived here using empirically determined values for raindrop terminal velocity. The calculated values of the extinction coefficient thus obtained provide much closer agreement with the measured values.
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