上升气流是成云致雨的基本条件之一.本文利用河北省2017年5月一次层积混合云的机载云物理探测系统测量资料,研究了云中上升气流速度分布,云微结构特征以及二者的相关性.结果表明:云中上升气流速度随高度呈抛物线型分布,云底部较小(0.75±0.52 m s-1),云中部最大(3.64±2 m s-1),云顶部最小(0.32± 0.29ms-1);发现随高度增加,云中上升气流区内冰粒子形状依次以片状、针状、柱状为主;暖云上升气流区中,上升气流速度与液态含水量正相关,相关系数为0.61;强垂直气流条件下云滴数浓度、最大云滴尺度大于弱垂直气流相应的数值,强垂直气流云粒子谱更符合r函数分布.
Abstract
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 Γ function distribution.
维普
万方数据