Airborne and ground‐based studies of thunderstorms in the vicinity of Langmuir Laboratory
Airborne and ground‐based studies of thunderstorms in the vicinity of Langmuir Laboratory
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朗缪尔实验室附近雷暴的机载和地面研究
DOI：
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发表时间：
1980
期刊：
影响因子：
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通讯作者：
J. Latham
中科院分区：
文献类型：
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作者：
H. Christian;C. Holmes;J. W. Bullock;W. Gaskell;A. Illingworth;J. Latham
1977年8月6日和15日，ONR/NMIMT Schweitzer飞机在新墨西哥州上空飞越雷暴中心地区，飞机携带的设备旨在测量电场的所有三个分量以及单个降水元素的电荷、q和直径d。当天早些时候，还通过以下方式获得了信息：朗缪尔实验室周围的雨量计网络；一个3厘米雷达；一个用于定位闪电通道的声学系统；一个陆基磁场变化仪。
8月6日的第一个单体在地面产生了降水，但没有闪电。云内记录到的垂直场Ex高达50kVm−1，降水电荷密度ρ高达−0.5C公里−3。第二个单体随着第一个单体的腐烂而生长，在9分钟内产生了7次闪电，在此期间雷达显示，在一个包含降水的狭窄区域内，垂直生长旺盛。
雷电重建显示，这个单体的第一次闪光的声源非常接近云层的顶部，高度为10公里a.s.1。随后的闪光产生了云中逐渐变低的声音信号。当雷达回波达到其最大高度时，闪电活动停止。测量了高达50kVm−1的ex值和低至−1 Ckm−3的pp值。ρp始终为负值，单次电荷小于±40pC。击穿时，Q值在雷云的感应值范围内，但Q与d之间没有系统关系。
8月15日的雷雨云进行了六次穿透，只产生了两次闪电。Ex记录表明，一个(±)偶极子位于云顶附近，在-13°C左右。测量了高达约100kVm的磁场−1和约5 cm的ρp值(正和负)−3。记录了高达±250 pC的Q值，电荷通常在±50 pC左右。没有发现系统的Q-d关系，较小的沉淀粒子经常携带超过感应极限的电荷(正电荷或负电荷)。
在这两天，估计的降雨率约为10 mm/h−1，在大多数情况下，飞行员报告的降水颗粒要么是冰，要么是液态水和冰的混合物。
Flights through the central regions of thunderstorms were made over New Mexico on 6 and 15 August 1977 with the ONR/NMIMT Schweitzer aeroplane which carried equipment designed to measure all three components of the electric field, and the charge, Q, and diameter, d, of individual precipitation elements. On the earlier day, information was also obtained with: a rain-gauge network surrounding Langmuir Laboratory; a 3 cm radar; an acoustic system for locating lightning channels; a ground-based field-change meter.
The first cell on 6 August produced precipitation at the ground but no lightning. Vertical fields, Ex, of up to about 50kVm−1 and precipitation charge densities ρ of up to −0.5 C km−3 were recorded within the cloud. The second cell, which grew as the first one decayed, produced 7 lightning strokes in 9 minutes during which time the radar revealed vigorous vertical growth in a narrow zone containing precipitation.
Thunder reconstructions showed the acoustic sources for the first flash of this cell to be very near the top of the cloud at an altitude of 10 km a.s.1. The subsequent flashes produced acoustic signals from progressively lower in the cloud. When the radar echo reached its maximum height lightning activity ceased. Ex values of up to about 50kVm−1 and pp values of down to −1 Ckm−3 were measured. ρp was consistently negative, individual charges being less than ±40 pC. Q values were within the inductive limit for a thundercloud at breakdown but no systematic relation between Q and d was found.
Six penetrations were made through the thundercloud of 15 August, which produced only two lightning strokes. The Ex records were indicative of a (±) dipole located near the cloud top, at around –13°C. Fields of up to about 100kVm−1 and ρp values (positive and negative) of around 5Ckm−3 were measured. Q values of up to ±250 pC were recorded, with charges around ±50 pC being commonly found. No systematic Q-d relation was revealed, and smaller precipitation particles frequently carried charges (positive or negative) in excess of the inductive limit.
On both days estimated precipitation rates were of order 10mmh−1 and on most occasions the pilot reported precipitation particles to be either ‘ice’ or ‘mixed liquid water and ice’.