Airborne studies of electric fields and the charge and size of precipitation elements in thunderstorms
Airborne studies of electric fields and the charge and size of precipitation elements in thunderstorms
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雷暴中电场以及降水元素的电荷和大小的机载研究
DOI：
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发表时间：
1978
期刊：
影响因子：
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通讯作者：
C. Moore
中科院分区：
文献类型：
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作者：
W. Gaskell;A. Illingworth;J. Latham;C. Moore
1976年夏天，ONR/NMIMT研究飞机被用于研究雷暴的电特性。作为雷雨研究国际项目的一部分，穿越云层的飞行在佛罗里达州和新墨西哥州进行。最重要的测量是电场和单个降水元素的电荷q和大小d。研制了一种用于Q和D测量的新型装置。粒子通过金属圆柱体携带的电荷是通过感应来检测的，其大小是通过一种涉及光电二极管线性阵列的阴影摄影技术来检测的。穿透一般是通过云层较低的区域。
在新墨西哥州进行的研究的主要结果如下：
1
在几公里的水平距离上，降水的体积电荷密度pp通常在-5nCm−3左右。PP几乎总是负的，但在较短的距离内偶尔可以观察到较低量级的正电荷密度。PP测量值的主要贡献者是尺寸在1 mm左右或更小的颗粒。
2.
Q和d的同时测量表明，它们之间不存在简单的关系。在大小约1 mm的颗粒上，通常观察到约100pc的电荷。这些都太高了，无法用归纳理论来解释。
3.
除沉淀率p很低外，正负电荷并存。然而，一个星座的电荷(几乎总是负的)总是占主导地位。
4.
P的值可以从d个脉冲粗略地估计出来。在PP高的地区，它们很少超过10 mm h−1；当PP很大时，有时p低于1 mm h−1。
我们的主要结论是，在所研究的云中，经常有大量的电流进行降水，从雷暴带电的诱导机制来看，单个降水元素上的电荷是无法解释的。
During the summer of 1976 the ONR/NMIMT research aeroplane was employed in studies of the electrical properties of thunderstorms. Flights through clouds were made in Florida, as part of the Thunderstorm Research International Project, and in New Mexico. The most important measurements were of electric field and the charge, Q, and size, d, of individual precipitation elements. A novel device was constructed for the Q and d measurements. The charge carried on a particle passing through a metal cylinder was sensed by induction, and its size by a shadowgraph technique involving a linear array of photo-diodes. The penetrations were generally through the lower regions of the clouds.
The major findings of the studies in New Mexico were as follows:
1
Volume charge densities on precipitation, pp, were often around - 5nCm −3 over horizontal distances of several kilometres. pP was almost always negative, but positive charge densities, of lower magnitude, were occasionally observed over shorter distances. The major contribution to the measured values of pP was made by particles of size around 1 mm, or smaller.
2
Simultaneous measurements of Q and d showed that no simple relationship existed between them. Charges of about 100pC were commonly observed on particles around 1 mm in size. These are much too high to be explicable in terms of the inductive theory.
3
Positive and negative charges were found to coexist, except when the precipitation rate, p, was very low. However, charge of one sign (almost invariably negative) was always strongly dominant.
4
Values of p could be estimated crudely from the d pulses. In regions of high pP they were rarely in excess of 10mmh−1; on some occasios when pP was substantial p was below 1 mmh−1.
Our primary conclusions are that in the clouds studied substantial currents were often carried on precipitation, and that the charges on individual precipitation elements are not explicable in terms of the inductive mechanism of thunderstorm electrification.