Abstract. Evolution of droplet size distribution (DSD) due to mixing between cloudy and
dry volumes is investigated for different values of the cloud fraction and
for different initial DSD shapes. The analysis is performed using
a diffusion–evaporation model which describes time-dependent processes of
turbulent diffusion and droplet evaporation within a mixing volume. Time
evolution of the DSD characteristics such as droplet concentration, LWC and
mean volume radii is analyzed. The mixing diagrams are plotted for the final
mixing stages. It is shown that the difference between the mixing diagrams
for homogeneous and inhomogeneous mixing is insignificant and decreases with
an increase in the DSD width. The dependencies of the normalized cube of the mean
volume radius on the cloud fraction were compared with those on normalized
droplet concentration and found to be quite different. If the normalized
droplet concentration is used, mixing diagrams do not show any significant
dependence on relative humidity in the dry volume. The main conclusion of the study is that traditional mixing diagrams cannot
serve as a reliable tool for analysis of mixing type.
Theoretical analysis of mixing in liquid clouds – Part IV: DSD evolution and mixing diagrams
