hebei provincial weather modification office
精细的云微物理特征是研究层状云降水机制的基础。利用“太行山东麓人工增雨防雹作业技术试验”的飞机和地面雷达观测数据，重点研究分析了2018年5月21日一次典型西风槽天气系统影响下的层状云微物理特征。结果表明，-5℃层的过冷水含量低于0.05 g?m-3，冰粒子数浓度量级101-102 L-1。冰粒子数浓度高值区主要以针状和柱状冰晶为主。这可能低层是Hallett-Mossop机制和其他冰晶繁生机制共同作用下所产生的冰晶碎片在冰面过饱和条件下凝华增长所形成的。冰粒子数浓度低值区的冰晶形状基本以片状或枝状为主。-5℃层的冰雪晶增长主要以凝华和聚并增长为主，凇附过程很弱。零度层附近云水含量峰值区的液态水占比达到70%以上。云水含量峰值区的粒子主要以直径10-50μm的云滴为主，伴随着少量聚合状冰晶。零度层其他区域的过冷水含量维持在0.05 g?m-3左右，冰晶形态主要以聚合状、凇附状及霰粒子为主。液水层则主要以球形液滴及半融化状态的冰粒子为主。垂直探测表明：零度层以上的冰雪晶数浓度呈现随高度递增的趋势。在发展稳定的层状云内，混合层的过冷水含量很低，冰粒子主要通过凝华和聚并过程增长，云体冰晶化程度较高。而在发展较为旺盛的层状云区里过冷水含量也较高，大量液滴的存在也表明混合层冰-液相之间的转化不充分。不同温度层的粒子谱显示，冷水含量高值区的冰粒子平均浓度比过冷水低值区高，但平均直径比过冷水低值区小。
Fine cloud microphysical characteristic is the research foundation of stratiform cloud precipitation mechanism. Based on the observation data obtained from "Rainfall Enhancement and Hail Suppression project at the eastern side of Taihang Mountains”, the stratiform cloud microphysical characteristics affected by the typical westerly trough process on 21 May, 2018 was analyzed. The result show that the super cold water content at the -5℃ layer is less than 0.05 g?m-3, and the concentration magnitude is 101-102 L-1. The needle-like and columnar ice crystals are often observed in the regions with high number concentration of ice crystal, which may be related to the ice crystal fragments which may be produced by Hallett-Mossop mechanism and other mechanism together were formed by deposition under super saturation respect to ice condition. Most of ice crystal is mainly plane and dendrites in the regions with low number concentration of ice crystal. The ice and snow crystal mainly grow through the process of deposition and coalescence, with weak rimming process. The liquid water content is accounted more than 70% in the regions with the peak value of cloud water content near 0℃ layer. The particle are mainly cloud droplet with diameter between 10 to 50 μm, accompanying with a few polymer. The super cold water content is about 0.05 g?m-3 in other regions near the 0℃ layer, and ice crystal habits are predominantly polymer、rimed and graupel type. Most of the particle are spherical droplet and melting ice crystal in the liquid water layer. The vertical detection show that the ice and snow crystal number concentration increased with height above 0℃ layer. The super cold water content of the mixed layer is much lower in the stable stratiform cloud. Most of particle are mainly grew through the deposition and coalescence, and the degree of ice crystallization is much higher. The existence of a lot of liquid droplets indicates that the transformation between liquid phrase and ice phrase is not sufficient in the strongly developed stratiform cloud regions in where supercooled liquid water is relatively abundant. The particle size distribution at different temperature levels indicate that the average number concentration of ice particle in the regions poor in super cold water content is higher than that of rich in super cold water content, however average diameter is on the contrary.