A Determination of the Condensation Coefficient of Water from the Growth Rate of Small Cloud Droplets

An experiment is described, in which the rate of growth of cloud droplets, in a thermal diffusion chamber, is measured accurately to yield the value of the condensation coefficient. The data obtained from measurements of 40 individual droplets grown at four different supersaturations (0.40,0.49,0.62 and 0.72%) suggests that the values of the condensation coefficient are 0.037, 0.033, 0.031 and 0.033, respectively; the average value is 0.033 with a standard deviation of 0.005. Probable sources of error are discussed and rejected.