Microstructure Study of the Updraft Zone of a Precipitation Cloud System in North China Based on Aircraft Observation

Updraft is a precondition for a cloud formation to cause precipitation. The vertical velocity distribution, cloud microstructure characteristics, and their correlation were analyzed based on airborne cloud physical detection system observations of a stratocumulus cloud in Hebei Province in May 2017. The results indicate that the updraft velocity in the cloud has a parabolic distribution with height: low at the cloud bottom (0.75±0.52 m s⁻¹), highest in the middle (3.64±2 m s⁻¹), and lowest at the cloud top (0.32±0.29 m s⁻¹). Additionally, with increasing height, the ice particles in the updraft area of the cloud are mainly sheet-, needle-, and column-shaped. The updraft velocity in the warm cloud updraft region and liquid water content are positively correlated, and the correlation coefficient is 0.61. Compared with the weak updraft condition, the stronger vertical airflow tends to form higher cloud droplet number concentrations and larger cloud drop diameters. The cloud droplet size mainly follows the Г function distribution.