Warm Cumulus Droplet Spectrum Of Growth And Seeding Numerical Simulation,

The evolution of droplet spectra within a warm maritime cumulus was studied in a one-dimensional, time-dependent cylindrical model using a sample of salt nuclei in maritime air. The macrostructure and microstructure of the simulated cloud was in good accordance with observations.Through analyzing the macro-micro structure of the simulated cloud, we found some characteristic about warm maritime cumulus as follows:1. The distribution of water content in warm maritime cumulus was in accordance with the distribution of updraft speed both in space and in time.2. The condensation of the salt nuclei was first initiated in larger ones. Cloud droplet spectra could be formed in a comparatively low level above cloud base and developed later in higher levels.3. The distribution of the droplet spectra dependant on height was that from above the cloud base, droplet spectra were first broadened then narrowed with the height, which closely related to the macro-structure of the cloud.After successfully simulated the cloud process in warm maritime cloud, we seeded it with artificial salt powders. It seemed that, as for warm maritime cumulus, the added salt powder did no good to the broadening of droplet spectra. With the same airplane seeding dosage, larger salt powders benefited more to the droplet spectra broadening than smaller ones, which might because that the formation of the large cloud drops was decided by the concentration of salt nuclei, having nothing with its size. The less concentration, the more large cloud drops. The added artificial salt powders increased the population of salt nuclei, which narrowed the cloud droplet spectra. At the same dosage, there contained more population in smaller salt powders than in larger ones, which resulted in the narrower spectra seeded with smaller salt powders than with larger ones.