Abstract:
This study analyzes the microphysical properties of precipitating and nonprecipitating warm clouds based on seven-flight cloud measurements from 6 November 2014 to 25 December 2014 in Jiangxi Province. The autoconversion threshold function (
T) represents the probability of collision–coalescence process occurrence in clouds, which is critical for determining the initial time and intensity of precipitation. The authors found that, in general,
T increases with height above the cloud base, with the maximum value occurring in the middle and upper parts of clouds. The occurrence frequency of
T>0.6 in the precipitating clouds is larger than that in the nonprecipitating clouds, indicating a stronger collision–coalescence process and a greater probability of raindrops generated by the condensation and collision–coalescence processes in the precipitating clouds. There is a negative relationship between the relative dispersion of cloud droplet size distribution (
ε) and the number concentration of cloud droplets (
Nc), and this negative relationship becomes more evident with increasing
T. Compared with the average radius of cloud droplets (
ra), the standard deviation of cloud droplet size distribution (
σ) dominates the enhancement of the degree of the negative relationship between
ε and
Nc.