As an essential part of physical process on cloud and precipitation， the falling process of raindrops is mainly related to evaporation and raindrop fallspeed.For a single cloud droplet in the stationary atmosphere， Maxwell's theory produces the mass growth formula of particles during the condensation process.In this study， the falling process of raindrops focuses on the evaporation process rather than the condensation process.Based on Maxwell’s theory， raindrops are assumed to be spherical particles， to produce its drop process by solving the original equation solved with difference method， and modifying the Maxwell theory by adding effects of ventilation and surface.For the issue of raindrop fallspeed， using the sounding data of Kunming station in 2015， the raindrops sample are divided into three groups according to different diameter (>1 μm).Neglecting the short acceleration process of raindrops， the balance between drag force and the gravity is considered for discussion.The relationship between the fallspeed and radius at the initial height is obtained by fitting with the least square method.And then the functional relationship between the fallspeed and radius at any height is obtained by combining some assumptions and theoretical derivation.Finally， several sensitivity experiments on relative humidity are tested by using this model.The result shows that decreasing the ambient relative humidity will accelerate the evaporation of small raindrops.Based on Maxwell's theory and other previous studies， this paper has obtained a more reasonable raindrop falling model by considering evaporation process through some assumptions， which is helpful to represent the realistic falling process of raindrops better.
Qiang JIANG
,
Jianchun BIAN
,
Yan LI
. Establishment of Model Prototype of Raindrop Dropping Process[J]. Plateau Meteorology, 2020
, 39(3)
: 609
-619
.
DOI: 10.7522/j.issn.1000-0534.2020.00004.
[1]Bashforth F， Adams J C， 1883.An attempt to test the theories of capillary action by comparing the theoretical and measured forms of drops of fluid［M］.London： Cambridge University Press, 320-413．
[2]Dennis L， Johannes V， al et， 2011.Physics and chemistry of clouds［M］.London： Cambridge University Press.
[3]Davies C N， 1945.Definitive equations for the fluid resistance of spheres［J］.Proceedings of the Physical Society， 6 (2)： 259-270．
[4]Lenard P， 1904.Ueber regen［J］.Meteorologische Zeitschrift， 21(2)： 248-262．
[5]Spilhaus A F， 1948.Raindrop size， shape， and falling speed［J］．Journal of Meteorology， 5(1)： 108-110．
[6]Ulrike L, al et， 2016.An Introduction to Clouds［M］.London： Cambridge University Press, 214-244.
[7]黄一民， 宋献方， 何清华， 等， 2018.洞庭湖流域下落雨滴蒸发研究[J].地理科学， 38(8)： 1364-1369.
[8]贾星灿， 牛生杰， 2008.空中、 地面雨滴谱特征的观测分析［J］．南京气象学院学报， 31(6)： 865-870．
[9]李其琛， 杜金林， 1964.下落过程中雨滴谱和雨的雷达反射率的变化[J].北京大学学报(自然科学)（3）： 283-289.
[10]刘雅君， 2001.雨滴下落的收尾速度[J].大学物理， 20(12)： 45-46.
[11]马宁堃， 刘黎平， 郑佳锋， 2019.利用Ka波段毫米波雷达功率谱反演云降水大气垂直速度和雨滴谱分布研究[J].高原气象， 38(2)： 325-339.DOI： 10.7522/j.issn.1000-0534.2018.00127.
[12]武威， 胡燕平， 2019.沙颍河流域一次基于高分辨资料的降水相态分析[J].高原气象， 38(5)： 983-992.DOI： 10.7522/j.issn. 1000-0534.2018.00128.
[13]吴兑， 1991.关于雨滴在云下蒸发的数值试验[J].气象学报(1)： 116-121.
[14]朱乾根，林锦瑞, 寿绍文, 等， 2000.天气学原理和方法[M].北京： 气象出版社， 320-400.
[15]张宇， 牛生杰， 贾星灿， 2013.雨滴下落过程谱分布演变的数值模拟［J］.大气科学学报， 36(6)： 699-707．
