Relationship between Critical Supersaturation and Cloud Droplet Size: Implications for Cloud Mixing Processes

Abstract

Cloud condensation nuclei (CCN) measurements within stratus clouds that have involved droplet separation have revealed a clear preference for droplet activation on the nuclei with the lowest critical supersaturations (Sc). When droplets of various sizes were separated from a sample, a consistent relationship between cloud droplet size and nucleus Sc was discovered?large droplets tend to grow on large (low Sc) nuclei and vice versa. Interpretation in terms of various modes of mixing between clouds and the dry environment demonstrates a preference for the homogeneous mixing process.