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1.
Kinetics of the air bubbles exhalation process, which occurs in overcooled cloud drops when they hit the hail or graupel particles surface. Analytical relationship between a number of bubbles generated in a drop and their size depending on the degree of overcooling of cloud drops is revealed. It is shown that the air bubbles exhalation, which accompanies the coagulation growth of hail particles, occurs on the principle of “ebullition” of the liquid on the surface of a hail particle. 相似文献
2.
B. A. Kamalov 《Russian Meteorology and Hydrology》2011,36(9):608-612
The hail cloud modification is carried out by means of the cloud seeding with AgI particles of submicron sizes, in order to
create nuclei competing with the natural ones for supercooled liquid droplet water, or in order to accelerate precipitation
generation. However, scientific research confirmed a primary role of giant and supergiant particles in generation of nuclei
of convective precipitation and hail. Such particles occur also at high levels (5 km and more). As the cloud and precipitation
particles grow mainly through coagulation, one can hardly expect a high success from the cloud seeding with AgI submicron
particles for hail suppression. In the hail process modification, the Ag particles settle down not at the nuclei but in the
hailstone layers. So, AgI is spent not for additional hail nuclei creation, but for intensification of coagulation growth
of natural cloud and precipitation particles. This can represent one of the main mechanisms for cloud modification. 相似文献
3.
A. A. Sin’kevich Yu. A. Dovgalyuk N. E. Veremei A. B. Kurov Yu. P. Mikhailovskii E. V. Bogdanov M. L. Toropova A. A. Ignat’ev A. Kh. Adzhiev A. M. Malkarova A. M. Abshaev V. Gopalakrishnan P. Murugavel S. D. Pawarr 《Russian Meteorology and Hydrology》2017,42(8):494-502
The three-dimensional nonstationary model of a convective cloud is used for investigating a thunderstorm with hail which developed over Pyatigorsk on May 29, 2012 and produced a severe hailstorm. The values of cloud characteristics (liquid water content, ice content, vertical velocity, etc.) are obtained. The importance ofconsidering wind shear is noted. The simulation results are used to analyze the transformation of precipitation field and the electric charge structure of the analyzed cloud during its development. 相似文献
4.
利用贵州省三维闪电监测网资料、新一代天气雷达资料、地面观测资料,对贵州省中西部地区13次冰雹天气过程中闪电特征进行了分析。结果表明：雹暴整个生命史内主要以负地闪为主,且伴随强降水。冰雹云发展阶段,降雹区域闪电频次增加明显,降雹前闪电频次变化均出现“跃增”,部分降雹点出现闪电频次二次跃增;冰雹云消散阶段,闪电频次显著减少。冰雹云总闪、正闪均高于雷雨云,5 min闪电频数大于16次且闪电频次上升度大于12次/5 min可作为识别冰雹云的参考指标。另外,降雹落区与闪电密度中心区域较为吻合,闪电密度中心位置略偏降雹位置之前,闪电逐时分布标识出冰雹云的发展移动方向。以上这些特征可以为冰雹识别、冰雹短时预警预报及人工防雹作业提供参考。 相似文献
5.
利用SD型闪电频数识别高原雷雨云和冰雹云 总被引：10，自引：2，他引：10
分析了青海省西宁市和互助县两地的闪电频数资料，结果表明，在青海省人工防雹区山多，地形复杂的情况下，使用SD型闪电计数器可以识别饱点周围40km的雷雨云和冰雹云，当雷暴由山区向平地移动时，5min闪电频数不小于40次，可作为作用的指标，而雷暴从平面向山区移动时，作业指标不小于30次／(5min)，雷暴云闪电频数的升度大于10次（5min)也可以作为识别雷雨云和冰雹云的指标，但时效较短，利用ＳＤ型闪电频数识别高原雷雨云和冰雹云是一种简便，经济实用的手段，有助于没有雷达等观测设备的偏僻山区防雹作业。 相似文献
6.
利用已有的二维雷暴云起电模式,加入气溶胶模块,建立一个完善的雷暴云起电模式.结合SEET个例,初步探讨了气溶胶浓度对雷暴云内各种水成物粒子荷电情况的影响.发现气溶胶的浓度与雷暴云内云滴、霰粒、冰雹以及雨滴等水成物粒子在空间所携带的最大电荷面密度值以及电荷量有很好的正相关性;同时气溶胶粒子浓度的增加使得雨滴在空间携带电荷量达到峰值的时间有一定提前. 相似文献
7.
冰雹作为一种短时强灾害天气,常给农业、建筑、电力、交通甚至生命财产等造成严重影响,人工防雹也因此受到人们的广泛关注。文中首先介绍了冰雹形成机理和雹云物理研究情况,然后围绕人工防雹机理、技术、科学试验及效果评估这4个方面的研究进行了评述,旨在从理论和实践上总结人工防雹工作的进展,增进对人工防雹科学问题的认知,从而为促进中国人工防雹理论研究和技术进步提供借鉴。研究表明:（1）“累积带理论”和“循环增长理论”是冰雹形成的最常见理论,限于早期的雷达观测技术和缺乏完整的冰雹数值模式,早期认知的冰雹形成机理存在一定的局限。（2）雹胚一般分为冻滴胚和霰胚,冻滴胚由过冷雨滴冻结而成,霰胚则是冰晶、雪花撞冻生长而成。冰雹云中哪种雹胚占优势,主要看云底温度的高低。雹云的发展依赖于水汽条件、动力不稳定条件、风垂直切变等关键因子。（3）人工防雹主要遵循“播撒防雹”和“爆炸防雹”2条技术路线,“利益竞争”和“早期降雨”是常见的6种防雹原理假说中最广泛被用来作为防雹作业设计依据的2种播撒防雹理论。（4）人工防雹技术上多采用通过飞机、地面火箭、地面燃烧炉等向云中播撒人工冰核,或通过地面高炮向云中发射含人工冰核的炮弹等方式,影响冰雹的生长过程从而达到抑制或削弱冰雹生长的目的。（5）大量外场试验证明人工防雹效果有较大的地域差异,需根据各地冰雹云特征及其降雹特点制定和发展本地适用的人工防雹技术体系。（6）人工防雹效果检验仍然是制约人工防雹技术发展的一个“瓶颈”,目前常用的统计检验、物理检验和数值模拟检验技术方法均需要进一步改进和完善。由于雹云变化迅速、降雹过程短促,人工防雹技术实施的时效性以及防雹效果评估仍存在较大的困难。今后应更多地借助多种探测设备进行冰雹云的精细化探测,开展有科学设计的人工防雹外场综合试验,运用统计检验、物理检验和数值模拟相结合的综合检验技术方法评估防雹效果,推动人工防雹事业进一步快速发展。 相似文献
8.
A cloud-resolving mesoscale model with a two-moment microphysical scheme has been used. The software package for cloud seeding and two categories of precipitation elements (graupel and frozen raindrops) are incorporated in the model. The aim of this study was to investigate the impact of cloud droplet concentration on hail suppression effectiveness. The concentration level of cloud droplets is prescribed in the model. We performed sensitivity tests of precipitation amounts (rain and hail) on the cloud droplet concentration in unseeded and seeded cases. We demonstrated for the unseeded case that increasing the concentration of cloud droplets created a reduction in rain accumulation, while the amount of hail accumulation increased. It is necessary to understand whether natural diversity in the cloud droplet concentration can affect the effectiveness of hail suppression. For operational cloud seeding activities, it would be helpful to determine whether it is possible to suppress hail if we know the optimal level of concentration for cloud droplets. Our study showed that hail suppression effectiveness had the greatest influence on lowering cloud droplet concentration levels; suppression effectiveness decreased as the cloud droplet concentration increased. 相似文献
9.
雷达回波顶高（ET）产品在广西冰雹云识别中的应用研究 总被引：1，自引：0，他引：1
利用广西2009至2012年降雹样本资料和新一代天气雷达回波顶高（ET）产品,对广西冰雹云回波顶高变化特征进行统计分析,结果显示广西冰雹云的ET整体呈现明显的阶段性变化特征,降雹时间和ET值达到最大值时间基本一致。冰雹云量化识别指标分别为：2月份回波顶高≥8km且回波顶高与0℃层高度差36.1km;3-4月份回波顶高≥10km且回波顶高与0℃层高度差≥6.1km;5月份回波顶高≥13且回波顶高与0℃层高度差38.1km。降雹直径与冰雹云ET值和特征层高度差值成正相关关系,可作为估计降雹直径的一个重要参考依据。 相似文献
10.
采用WRF模式与包含了云凝结核(Cloud Condensation Nuclei,CCN)浓度和霰雹密度预报的NSSL(National Severe Storm Laboratory,国家强风暴实验室)微物理方案,模拟不同CCN初始浓度条件下南京地区的一次冰雹云过程,分析不同CCN初始浓度影响下冰雹云过程的宏微观演变特征,以及对流发展不同阶段的水凝物粒子及流场、温度场的垂直分布特征。研究发现:1)较大的CCN初始浓度虽然抑制了前期对流降水,但对后期对流降水的产生有促进作用;2)CCN初始浓度的增加使得模拟雷达回波的强回波区域(大于40 dBz)缩小,中等强度区域(小于40 dBz)扩张。3)CCN初始浓度增大不利于对流发展初期云雨自动转化过程的发生,但是促进了冰晶与雪的产生,使得冰雹含量峰值出现的时间推迟。4)CCN浓度增大抑制了雨水产生,间接使得霰粒子更倾向于干增长,平均密度更小;5)较大的CCN浓度促使冰雹云单体的发展时间增长。 相似文献
11.
利用模拟测试方法研究了几个重要因子对冰雹指数误差的影响,并根据遵义新一代多普勒天气雷达资料,使用探测概率、临界成功指数和误报率为衡量指标,对2008年3月到2012年7月12次冰雹天气过程中25个降雹风暴和72个非降雹风暴的冰雹指数进行分析评估。结果表明：H0、反射率因子垂直廓线和目标离雷达的距离等因子对POSH误差的影响较大,Hm20对其影响较小。POH识别冰雹云的误报率较高,临界成功指数较小;POSH识别效果好于POH,通过增大阈值可以提高临界成功指数和减小误报率,但是当阈值太大时,探测概率会较低,为了获得较大的探测概率和临界成功指数,减小误报率,以POSH=70为阈值时识别效果最好;在POSH识别冰雹云时加上VIL>20 kg·m-2的条件对探测概率没有影响,但是当阈值小于90时,可以减少误报率和提高临界成功指数。 相似文献
12.
A. M. Malkarova 《Russian Meteorology and Hydrology》2011,36(6):392-398
Results are considered of study of climate global warming effects on hail climatology and on technique of estimation of physical
efficiency of hail protection taking account of the region hail danger trend. It is found that during last 30 years, occurrence
frequency of hail and the number of heavy hailstorms in the mountainous areas of the Northern Caucasus decreased, on average,
by a factor of 1.5–2, and in the foothill areas increased by 15–20%. It is shown that efficiency of hail protection works
should be estimated taking into account the hail danger trend for each region. 相似文献
13.
强风暴个例电荷结构及云闪放电差异的数值模拟 总被引：1，自引：0，他引：1
利用耦合电过程的冰粒子分档模式对长春地区两个降雹型和非降雹型强风暴个例的闪电特征进行了模拟和对比分析。结果表明,在雷暴云的初始发展期,由于上升气流较弱,两者电荷分布相似,均表现为弱的正偶极结构。随着云体不断发展,两者电荷分布开始表现出差异:降雹型个例中的上升气流较强,风切变较大,过冷水能被携带到较高的高度,冰相粒子也能被带到较高处或在较高处继续增长,使得不同区域均存在冰相粒子含量中心。因此,冰相粒子的发生范围不同、环境参数不同及荷电符号不同的非感应起电过程,形成多个电荷中心,电荷结构易出现多层分布。在不同的发展时期电荷结构均呈现出不同的形态,放电既可能在上升气流区触发,也可能在气流辐散区触发。相对而言,非降雹型个例中的上升气流较弱,风切变较小,冰相粒子的分布较规则,非感应起电过程较均匀,从而导致电荷分布始终较均匀。不同发展时期的电荷结构都相对有规则,满足放电条件的位置具有一定的相似性。 相似文献
14.
15.
利用常规气象观测资料、章丘站探空资料及滨州、济南新一代SA天气雷达探测资料,对2016年6月14日发生在山东中部地区一次强降雹天气过程进行分析。结果表明：雷暴发生前大气不稳定能量的明显增加,较强垂直风切变是有利于强对流天气发生的环境条件;长寿命超级单体沿两山之间的谷地运动,地形对雹体发生、发展起到了抬升和维持作用,对单体的移动起到了导向作用;雷暴发生前的垂直累积液态水含量（VIL）跃增对冰雹粒子的形成和增长十分有利;超长的三体散射（TBSS）、深厚而持久的中气旋、高悬的强反射率中心、有界弱回波区以及风暴顶强烈辐散都是大冰雹发生的显著特征。 相似文献
16.
Kh. M. Zhakamikhov M. K. Zhekamukhov V. S. Inyukhin 《Russian Meteorology and Hydrology》2010,35(8):530-535
The hail cloud parameters are computed on the basis of jet convection model using the real atmospheric stratification. The
analysis of these computations shows the opportunity to use the jet convection model for the operative forecast of hailstorms
and their intensity. 相似文献
17.
采用耦合了Saunders和Takahashi两种非感应起电参数化方案的RAMS(Regional Atmospheric Modeling System)模式,对重庆地区一次雷暴过程进行模拟,对比分析了两种起电参数化方案下,电荷开始分离时和雷暴云发展到成熟阶段时的水成物粒子的分布、所带电荷密度以及雷暴云的电荷结构分布。模拟结果表明,在Saunders起电参数化方案下,雷暴云的电荷结构从起电到放电都呈现偶极性特征,而在Takahashi参数化方案下,雷暴云的电荷结构则由反偶极性发展成正偶极性。为研究CCN(cloud condensation nuclei)对雷暴云的影响,本文进行了两组敏感性试验,随着云滴初始数浓度增加,雷暴云的电荷结构没有发生极性翻转,但雷暴云中电荷量增加,电荷分布区域变大,有利于闪电发生。在Saunders起电参数化方案下,当云滴初始数浓度大于2 000 cm-3时,电荷量变小。通过分析微物理量场和微物理过程发现,随着云滴初始数浓度增加,冰相粒子质量混合比增加,在Saunders起电参数化方案下,当云滴初始数浓度大于2 000 cm-3时,霰粒子质量混合比减小。验证了CCN的变化能影响云的微物理过程,从而影响雷暴云的电荷分布以及闪电的发生,尤其是冰相物质的变化显著影响了雷暴云的起电过程。 相似文献
18.
M. T. Abshaev A. M. Abshaev A. M. Malkarova M. V. Zharashuev 《Russian Meteorology and Hydrology》2010,35(3):182-189
Methods, algorithms, and programs of automated radar identification of convective cells in cumulonimbus clouds are considered,
that provides the ability to measure the parameters of convective cells, to plot the graphs of the time course of parameters,
to compute the direction and speed of the movement, to assess their thunderstorm and hail danger, and to recognize the categories
of target objects for the prevention of hail damage and meteorological provision of aviation. 相似文献
19.
A multiparameter radar case study of the microphysical and kinematic evolution of a lightning producing storm 总被引：7，自引：0，他引：7
Summary We examine the co-evolving microphysical, kinematic, and electrical characteristics of a multi-cell thunderstorm observed on 21 May 1993 along the Front Range of Colorado using data collected with the 11 cm, multiparameter, CSU-CHILL Doppler radar. The measured polarimetric variables provide information on the size, shape, orientation, and thermodynamic phase of hydrometeors. Recent modeling and observational advances in weather radar polarimetry now permit the inference of bulk-hydrometeor types and mixing ratios, and the measurement of precipitation rate in mixed-phase (i.e., hail and rain) environments. We have employed these and other radar techniques, such as dual-Doppler analyses, to investigate the correlation between the convective life cycle of a multi-cell storm and the evolution of lightning type and flash rate.The observations suggest a strong correlation between the radar-inferred graupel volume suspended in a vigorous updraft in upper-portions of the storm and the in-cloud (IC) lightning flash rate. Our analyses reveal that maxima in the hail rate are related to peaks in the cloud-to-ground (CG) lightning flash rate. Both correlation's are consistent with the non-inductive charging mechanism which relies on collisions between graupel/hail particles and ice crystals in the presence of supercooled water. Peaks in storm outflow are shown to either lag or to coincide with maxima in both the CG flash rate and hail rate. The amount and vertical location of ice in this storm was also related to the strength and polarity of the electric field through observations of a Field Excursion Associated With Precipitation (FEAWP) and a subsequent microburst. We demonstrate that the FEAWP was coincident with the descent of graupel and small hail below the charge reversal level as explained by the non-inductive charging mechanism, and that the further descent of graupel and small hail below the melting level aided in the generation of a microburst near the surface. Using observations of the FEAWP, we present some comparative speculation on the microphysics of the associated lower positive charge center and the applicability of various laboratory charging studies.With 14 Figures 相似文献
20.
Jambajamts Lkhamjav Han-Gyul Jin Hyunho Lee Jong-Jin Baik 《Asia-Pacific Journal of Atmospheric Sciences》2017,53(4):501-509
The temporal and spatial characteristics of hail frequency in Mongolia are examined using the hail observation data from 61 meteorological observatories for 1984-2013. The annual number of hail days averaged over all observatories and the entire period is 0.74. It exhibits a decreasing trend, particularly since 1993 with a rate of decrease of 0.214 per decade. Hail occurrence is concentrated in summer, with 72% of the total hail days occurring in June, July, and August. Moreover, hail occurrence is concentrated in the afternoon and early evening, with 89% of the total hail events occurring between 1200 and 2100 local standard time (LST). Spatially, observatories where relatively frequent hail events are observed are concentrated in the north central region where almost all of the land is mountainous or covered by grassland, whereas relatively less frequent hail events are observed in the southern desert region. The relationship between hail frequency and thermodynamic factors including the convective available potential energy (CAPE), the temperature lapse rate between 700 and 500 hPa, the water vapor mixing ratio averaged over the lowest 100 hPa layer, and the freezing-level height is examined using the ERA-Interim reanalysis data. It is found that in summer, CAPE and the low-level water vapor mixing ratio are larger on hail days than on all days, but there is no clear relationship between hail frequency and the 700-500 hPa temperature lapse rate. It is also found that annually, CAPE and the low-level water vapor mixing ratio decrease, while the freezing-level height increases, which seems to be responsible for the annually decreasing trend of hail frequency in Mongolia. 相似文献