Summary

One of the goals of the Small Cumulus Microphysics Study (SCMS), which was conducted in the summer of 1995 near Cape Canaveral, Florida, was to study warm cumuli in their earliest stages, with the goal of understanding the factors that control the time to onset of precipitation. There were significant variations from day to day in the cloud condensation nuclei (CCN) concentrations, ranging from more maritime conditions (359 ± 142 cm^3) to continental conditions (1411 ± 388 cm^3) (Hudson and Yum 2001, hereafter HY01). In the SCMS clouds higher CCN concentrations suppressed drizzle formation.

During SCMS, small cumuli were studied using radar, three instrumented aircraft, atmospheric soundings, and time-lapse videos. Small cumuli typically first appeared in midmorning and developed precipitation when their tops reached 3 to 4 km MSL. Precipitation typically developed within 20 to 30 min of the initial detection of the clouds with radar. The clouds in this study were all isolated and had tops with temperatures >0°C. During SCMS, radar data were collected on 44 consecutive days from 3 July through 19 August 1995. The early portion of the project was a radar-only period. Special project soundings were launched one to four times per day at the radar site early in the project (3-16 July) or 22 km southwest of the radar later in the project (20 July-14 August).