Radar Reflectivity of Cumulus Clouds

Abstract

The relationships between the radar reflectivity factor Z and significant physical cloud parameters are studied from a dataset collected with an instrumented aircraft in non- or very weakly precipitating warm clouds. The cloud droplet populations for each flight are statistically described from histograms showing the relative importance and the extent of the precipitating and nonprecipitating component in the cloud field. The limit between precipitating and nonprecipitating warm clouds is found to be about Z = 0.032 mm6 m?3 (? 15 dBZ). No clear correlation appears between Z and liquid water content or median volume diameter in cloud samples that contain droplets larger than about 200 ?m in diameter. Some relationships are proposed for smaller droplets in natural clouds. No significant difference is found between dynamically induced artificial clouds and natural ones.