Observations of the connection of positive and negative leaders in meter-scale electric discharges generated by clouds of negatively charged water droplets
Observations of the connection of positive and negative leaders in meter-scale electric discharges generated by clouds of negatively charged water droplets
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DOI：
10.1002/2016jd025079
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发表时间：
2016-08-27
影响因子：
4.4
通讯作者：
Rakov, V. A.
中科院分区：
文献类型：
--
作者：
Kostinskiy, A. Yu.;Syssoev, V. S.;Rakov, V. A.
详细观察了带负电水滴云产生的米级放电中正负先导之间的连接，并讨论了它们对闪电附着过程的可能影响。使用三种不同高速相机（带图像增强的可见光范围、常规可见光范围和红外）获得的光学图像以及相应的当前记录。首次呈现了领导者连接突破阶段的两个快照，显示了公共流送区域内的重要领导者分支。发现两个事件的公共流光区域内的正和负领导者速度相似。较高的先导速度通常与较高的先导电流相关。在头对头引线连接的情况下，连接区域的红外亮度（可能代表气体温度，因此代表能量输入）通常比该区域下方或上方的通道部分高 5 倍左右。在 16% 的情况下，向下的负先导在其尖端下方连接到向上的正先导（连接到正先导的侧面），连接是通过看起来垂直于一个或两个先导通道的通道段完成的。
Detailed observations of the connection between positive and negative leaders in meter-scale electric discharges generated by clouds of negatively charged water droplets are presented, and their possible implications for the attachment process in lightning are discussed. Optical images obtained with three different high-speed cameras (visible range with image enhancement, visible-range regular, and infrared) and corresponding current recordings were used. Two snapshots of the breakthrough phase of the leader connection, showing significant leader branching inside the common streamer zone, are presented for the first time. Positive and negative leader speeds inside the common streamer zone for two events were found to be similar. Higher leader speeds were generally associated with higher leader currents. In the case of head-to-head leader connection, the infrared brightness of the junction region (probably representing the gas temperature and, hence, the energy input) was typically a factor of 5 or so higher than for channel sections either below or above that region. In 16% of cases, the downward negative leader connected to the upward positive leader below its tip (attached to the lateral surface of the positive leader), with the connection being accomplished via a channel segment that appeared to be perpendicular to one or both of the leader channels.