Real-time measurements of droplet size distribution in Antarctic coastal clouds

The instrumentation and procedure used in real-time measurement of cloud droplet size are described briefly. A table summarizes the observed and calculated parameters of sampled clouds, giving cloud base height, cloud droplet concentration, cloud base temperature, droplet diameter, and liquid water content. All clouds exhibit bimodal size distribution of varying degrees with an initial peak in concentration of diameters < 4 mu m. The diameter at which the second peak occurs is between 12 and 16 mu m, and it is this peak that seems to vary with height. The bimodal size distribution may be explained on the basis of the entrainments of the surrounding air. Various theories explaining this process and theories of cloud droplet growth are briefly summarized.