飞机云

明朗的秋空常常飘荡着团团云彩。我们经常看到,飞机穿云而出,在高高的天空中飞行着。 此刻,仰望晴空,只见飞机吐着雪白的线条向前飞去。这就是飞机云。它从远处的云群中钻出来,一直向前延伸,就象飞机把云曳着向前而去。 飞机云到底是什么呢?这就是飞机掠过空中时所产生的云,而不是它把飘荡着的云向前拽。那么,飞机云又是怎样产生的呢?我们知道,海水和陆地包含水份,当受到太阳的照射时,就会慢慢地蒸发,变成水蒸气,搀杂于空气之中。这种水蒸气在高空中受到冷却,骤然凝成许多细小的水珠,它们聚合在一起,就变成了云。     

碎云

伴随着恶劣天气而出现在降水云层之下的碎云是碎雨云,这是无可非议是。可是,当降水天气发生之后,在测站四周山腰生成的碎云是否亦是碎雨云?这个问题倒是值得提出讨论的。 根据“贯例”,每逢有这种云出现,我们都把它记为碎雨云。笔者最近经过实地观察,认为应把这种云记为碎层云为妥。 不可否认,降水天气之后在山地所生成的碎云也是降水物蒸发后,使之水汽含量增大达到饱和凝结而成,仅从这点来看,它与前者碎雨云的生成有共同之处——都是降水物蒸发后所凝结之产物。但是它们在生成过程则有差异。     

播云

人工影响天气(播云)计划的目的是:增加降雨或降雪,以解决供水和(或)水力发电的需要.人工播云计划的发起者们认为这些计划使降水的年平均泾流量增加了5%～15%.在过去35年以上的时期内,各种统计分析方法被用来对这些计划的效果进行评价.进行精确的评价是困难而花费昂贵的,但是却表明有些风暴能够依靠人工播云技术提高“水汽转变为降水”的自然效率. 加利福尼亚州水资源部在菲什尔河流域的较高地区设计了一项人工影响天气计划.1988年夏季以前,这项设计来为州的水资源计划增加供水量的人工影响天气计划,已在     

“云绞云,雨淋淋”

“云绞云,雨淋淋”这句谚语,不仅在西藏高原地区流传着,在我国其它许多地区也广泛地流传着。它的含意是,在夏季里,当天空有自西移来的高云,同时又有低云自东向西(或自南向北)移动时,预示着未来天气要变坏。气象观测经验也表明,夏季测站出现这种云天,则意味着高低空有气流切变,表示某种天气系     

云码歌

云族分为高中低,电码三九二十七,莫搞颠倒莫错乱,编报规定应熟悉。几种云状在一起,一般选报最大的。一族无云编报O,不明编x没问题。低云淡1浓23秃积,积性层积电码4,普通层积应报5,层云碎层把6记,恶劣天气碎雨7,碎层碎积坏天气,积云层积异高8,9的云码察积雨。中云高层透l,2蔽雨,高积稳3、荚变4,系侵天空高积5,积性高积6无疑,高层高积同存时,高积蔽光双层7,堡状絮状都编8,全昆乱天空9高积。 高云卷云毛1,2为密,伪卷编3,钩卷4,角小45)变把5编,6为大于45度角,布满全天卷层7,8为卷层有缝隙,五乏后还剩一种云,卷积报9请注意。云码歌@薜存福$韩城…     

激光测云

本文概述国内外激光测云的现状。介绍了激光测云高、云厚和层次;激光探测云的演变、云的波动和云中不均匀结构;激光探测云滴谱及消光系数等研究结果。并简要展望了激光在气象探测中的广阔前景。     

EFFECTS OF STRATIFORM CLOUD ON THE DEVELOPMENT OF CUMULUS CLOUD AND ITS PRECIPITATION

Based on the two-dimensional slab-symmetric model of cumulus clouds established by the authors,thedevelopment of the cumulus cloud and its precipitation in environments with and without the stratiform cloudpresent has been simulated numerically in almost the same atmospheric stratification.Results show that thepresence of the stratiform cloud has a significant effect on the development of the cumulus cloud and theincreae of its precipitation.The rainfall may increase by scveral to tens of times.It is believed that theconvective-stratiform mixed cloud system may be important for producing heavy to torrential rain.This isin good agreement with what has been observed in the Meiyu frontal cloud system in recent investigations     

梅雨锋云系中尺度系统回波结构及其与暴雨的关系

梅雨锋云系中中尺度回波带主要有对流带和混合带二种类型,中尺度回波团一般为混合型回波。对流云回波带在初生、成熟和消散三个不同的演变阶段结构特征不同,下垫面对回波带的演变有一定的影响。中尺度系统能够产生高强度降水,多个中尺度系统相继通过一地或中尺度系统与对流回波群的汇集可以造成梅雨期的局地性暴雨和大暴雨。产生暴雨的中尺度系统常具有混合型回波结构,它们降水强度大,对降水的贡献也大。     

NUMERICAL SIMULATION STUDY OF CLOUD INTERACTION AND FORMATION MECHANISM OF HEAVY RAIN IN MIXED CONVECTIVE-STRATIFORM CLOUD

Using the numerical model of mixed convective-stratiform clouds(MCS)in the paper(Hong1997)and the averaged stratification of torrential rain processes,the evolution processes,interaction of the two kinds of clouds,structure and the precipitation features in the MCS toproduce heavy rain are simulated and studied,and the physical reasons of producing torrential rainare analysed.The results indicate that the stratiform cloud surrounding the convective cloudbecomes weakened and dissipates in the developing and enhancing of the convective cloud,and therainfall rate and water content in the stratiform cloud increase as the distance from the convectivecloud becomes larger.The numerical experiments find out that the stratiform cloud provides abenificial developing environment for the convective cloud,i.e.,the saturated environment and theconvergence field in the stratiform cloud help to lengthen the life cycle of the convective cloud,produce sustained rainfall with high intensity and intermittent precipitation with ultra-highintensity.These and the ice phase microphysical processes are the main factors for the torrentialrain formation and the MCS is a very effective precipitation system.     

ANALYSING THE CLOUD MICRO- AND MACRO-PHYSICAL PROPERTIES OF THE CYCLONE EYE WALL AND ITS SURROUNDING SPIRAL CLOUD BANDS BASED ON CLOUDSAT AND TRMM DATA

In this study, the micro- and macro-physical properties, thermal structure and precipitation characteristics of cyclone eye walls and their surrounding spiral clouds were analysed with CloudSat and TRMM data for five tropical cyclones (TCs) in 2013. The results show that the ice-phase clouds of a mature TC are mainly above 5 km. With increasing altitude, the cloud droplet effective radius decreases, and the particle number concentration increases. Ice water content first increases and then decreases with increasing height. In the eye area, in addition to the well-known warm-core area, another warm core is also apparent around the eye at a height of 8 to 15 km. The horizontal distribution of precipitation is characterized by large-scale stratiform precipitation mixed with independent convective precipitation. The height of precipitation is mostly below 7.5 km, and the heavy rain is mainly below 5 km. When the peripheral convective clouds are strong enough, ice particles would be generated, thus providing conditions that are favourable for the formation of precipitation below.     

EVALUATION OF CONVECTIVE-STRATIFORM RAINFALL SEPARATION SCHEMES BY PRECIPITATION AND CLOUD STATISTICS

In this study,two convective-stratiform rainfall partitioning schemes are evaluated using precipitation and cloud statistics for different rainfall types categorized by applying surface rainfall equation on grid-scale data from a two-dimensional cloud-resolving model simulation.One scheme is based on surface rainfall intensity whereas the other is based on cloud content information.The model is largely forced by the large-scale vertical velocity derived from the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment(TOGA COARE).The results reveal that over 40% of convective rainfall is associated with water vapor divergence,which primarily comes from the rainfall type with local atmospheric drying and water hydrometeor loss/convergence,caused by precipitation and evaporation of rain.More than 40% of stratiform rainfall is related to water vapor convergence,which largely comes from the rainfall type with local atmospheric moistening and hydrometeor loss/convergence attributable to water clouds through precipitation and the evaporation of rain and ice clouds through the conversion from ice hydrometeor to water hydrometeor.This implies that the separation methods based on surface rainfall and cloud content may not clearly separate convective and stratiform rainfall.     

南京"03.7"大暴雨中云物理过程的数值模拟研究

利用三维全弹性、双参数化对流云模式和南京站探空资料,对南京“03．7”特大暴雨过程进行了数值模拟研究,着重分析产生这次大暴雨的云物理机制。模拟结果表明,此次暴雨属于积雨云降水,其中云雨碰并是最主要的成雨过程,贡献率达到74％,其次是霰／雹融化,占22％,说明此次降水以暖雨过程为主。通过暖雨过程对比试验表明,虽然冰相过程对雨水的贡献较小,但加入冰相过程能使模拟结果更接近云的实际情况。     

CLOUD RADIATIVE AND MICROPHYSICAL EFFECTS ON THE RELATION BETWEEN SPATIAL MEAN RAIN RATE, RAIN INTENSITY AND FRACTIONAL RAINFALL COVERAGE

Cloud radiative and microphysical effects on the relation between spatial mean rain rate, rain intensity and fractional rainfall coverage are investigated in this study by conducting and analyzing a series of two-dimensional cloud resolving model sensitivity experiments of pre-summer torrential rainfall in June 2008. The analysis of time-mean data shows that the exclusion of radiative effects of liquid clouds reduces domain mean rain rate by decreasing convective rain rate mainly through the reduced convective-rainfall area associated with the strengthened hydrometeor gain in the presence of radiative effects of ice clouds, whereas it increases domain mean rain rate by enhancing convective rain rate mainly via the intensified convective rain intensity associated with the enhanced net condensation in the absence of radiative effects of ice clouds. The removal of radiative effects of ice clouds decreases domain mean rain rate by reducing stratiform rain rate through the suppressed stratiform rain intensity related to the suppressed net condensation in the presence of radiative effects of liquid clouds, whereas it increases domain mean rain rate by strengthening convective rain rate mainly via the enhanced convective rain intensity in response to the enhanced net condensation in the absence of radiative effects of liquid clouds. The elimination of microphysical effects of ice clouds suppresses domain mean rain rate by reducing stratiform rain rate through the reduced stratiform-rainfall area associated with severely reduced hydrometeor loss.     

HORIZONTAL AND VERTICAL DISTRIBUTIONS OF CLOUD COVER OVER EASTERN CHINA AND THE EAST CHINA SEA

Based on data from satellite and surface observations,the horizontal and vertical distributions of clouds over eastern China and the East China Sea are examined.Three maximum centers of cloud cover are clearly visible in the horizontal distribution of total cloud cover.Two of these maxima occur over land.As the clouds mainly originate from the climbing airflows in the southern and eastern slopes of the Tibetan Plateau,they can be classified as dynamic clouds.The third center of cloud cover is over the sea.As the clouds mainly form from the evaporation of the warm Kuroshio Current,they can be categorized as thermodynamic clouds.Although the movement of the cloud centers reflect the seasonal variation of the Asian summer monsoon,cloud fractions of six cloud types that are distinct from the total cloud cover show individual horizontal patterns and seasonal variations.In their vertical distribution,cloud cover over the land and sea exhibits different patterns in winter but similar patterns in summer.In cold seasons,limited by divergent westerlies in the middle troposphere,mid-level clouds prevail over the leeside of the Tibetan Plateau.At the same time,suppressed by strong downdraft of the western Pacific subtropical high,low clouds dominate over the ocean.In warm seasons both continental and marine clouds can penetrate upward into the upper troposphere because they are subject to similar unstable stratification conditions.     

云和雨的相干散射与雷达气象方程

研究了云雨质点对雷达波的相干散射,从而推得比较普遍的雷达气象方程。旧的雷达气象方程是新方程在云雨质点互相独立时的特殊表现形式。对新方程作了一些讨论,发现旧方程之所以在某些方面与实验不符,可能是因为忽略了相干散射作用的缘故。     

云层分布对辐射增效和冷却的影响

本文计算了冬、夏两季在平原和高原地区分别有低云、高云和当高、低云同时出现时的短波辐射增热率,长波辐射冷却率以及高低云之间的相互影响。结果发现:1)高原上云的短波增热率和长波冷却率要比平原上的大,低云的增热和冷却较平原尤甚。2)高云存在时,地面附近由冷却变为增热。3)高原地区出现双层云时总是使地面附近增热。4)当两层云同时出现时,高云的短波增热率和长波冷却率都有所增大,低云的短波增热率减小,低云的长波冷却率则减小很多。5)低云量的变化对高云的冷却影响较小,而高云量变化对低云的冷却影响甚大。6)云的短波辐射增热受地面反照率的影响不很大,但对太阳高度角的变化甚为敏感。 由以上结果看来,在大气环流和气候模式中必须要很好地考虑高云云量的变化,否则难以得到好的结果。在区域气候模式中不可忽略高原地区和平原地区云的辐射增热和冷却作用的差别。