Influence of low-level wind speed on droplet spectra near cloud base in trade wind cumulus

Weak winds were associated with fewer activated cloud droplets, larger mean droplet sizes, and more large cloud droplets, even though the concentration of giant/ultragiant sea-salt aerosol increased with increasing near-surface wind speed.

The data suggest that in unpolluted trade wind cumuli: (1) the production of large cloud droplets near cloud base is controlled primarily by the intensity of the cloud base updraft rather than the concentration of giant/ultragiant sea-salt particles; (2) higher droplet concentrations are more likely under conditions of stronger low-level wind speeds, primarily because stronger low-level wind speeds are associated with more intense cloud base updrafts.