Abstract
An AN/TPS-10 radar, located at the Institute of Atmospheric Physics, University of Arizona, has been used to make extensive measurements of radar returns from cumulus clouds in the vicinity of Tucson. Data from ten days in the summer of 1955 have been analyzed with a view toward establishing the level of first formation of precipitation, day-to-day variation, average dimensions of first echo, average duration, and fraction reaching ground. Strong day-to-day variations and mountain effects are revealed. Although echoes form much more frequently over mountains than over nearby valleys, these echoes individually are less likely to produce rain at the ground.
