Cloud Condensation Nucleus Size Distributions and Their Effects on Cloud Droplet Size Distributions

Abstract

Abstract Cloud droplet size distributions, calculated from cloud condensation nucleus (CCN) measurements made beneath non-raining, warm clouds in western and eastern Washington State, show reasonable agreement with droplet size distributions measured in the clouds. The results of both the measurements and the calculations show that high concentrations of large (0.2≤D≤2 µm) and giant (D≥2 µm) CCN lead to droplet size distributions which contain large droplets (D≥30 µm) only if low concentrations of small (0.06≲D<0.2 µm) CCN are present. If high concentrations of small CCN are present, the droplet size distributions contain few, if any, large droplets, regardless of the concentrations of giant CCN.