Electrical discharge from a thundercloud top to the lower ionosphere
Electrical discharge from a thundercloud top to the lower ionosphere
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DOI：
10.1038/416152a
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发表时间：
2002-03-14
期刊：
影响因子：
64.8
通讯作者：
Wood, TG
中科院分区：
文献类型：
--
作者：
Pasko, VP;Stanley, MA;Wood, TG
一个多世纪以来，出现了许多关于雷雨云上空不寻常的大规模发光现象的未记录报告（1-6），80多年前，有人提出放电可以弥合雷雨云和高层大气之间的差距（7,8）。从那时起，雷雨云上方的两类垂直延伸的光学闪光已经被确定——精灵（9-11）和蓝色喷射（12-14）。精灵在电离层底部附近开始，以超过10(7)米每秒（-1）的速度向下迅速发展（参考文献15），并呈现许多不同的几何形状（16-19）。相比之下，蓝色喷流以10(5)m s（-1）的速度从云顶向上发展，并以蓝色锥形（12-14）为特征。但是，没有关于精灵或蓝色喷流的实验数据被报道，这些数据最终表明它们在雷云和较低的电离层之间建立了电接触的直接路径。在这里，我们报告一段视频，记录了一股蓝色的射流从雷雨云向上传播到大约70公里的高度，拍摄于波多黎各的阿雷西博天文台。在42公里以上的高度——通常是蓝色喷流的上限，精灵喷流的下限——闪光表现出精灵喷流中通常观察到的一些特征。当我们在一个相对较小的雷暴单体上方观察到这种现象时，我们推测它可能是常见的，因此代表了全球电路中一个未知的组成部分。
For over a century, numerous undocumented reports have appeared about unusual large-scale luminous phenomena above thunderclouds(1-6) and, more than 80 years ago, it was suggested that an electrical discharge could bridge the gap between a thundercloud and the upper atmosphere(7,8). Since then, two classes of vertically extensive optical flashes above thunderclouds have been identified-sprites(9-11) and blue jets(12-14). Sprites initiate near the base of the ionosphere, develop very rapidly downwards at speeds which can exceed 10(7) m s(-1) (ref. 15), and assume many different geometrical forms(16-19). In contrast, blue jets develop upwards from cloud tops at speeds of the order of 10(5) m s(-1) and are characterized by a blue conical shape(12-14). But no experimental data related to sprites or blue jets have been reported which conclusively indicate that they establish a direct path of electrical contact between a thundercloud and the lower ionosphere. Here we report a video recording of a blue jet propagating upwards from a thundercloud to an altitude of about 70 km, taken at the Arecibo Observatory, Puerto Rico. Above an altitude of 42 km- normally the upper limit for blue jets and the lower terminal altitude for sprites-the flash exhibited some features normally observed in sprites. As we observed this phenomenon above a relatively small thunderstorm cell, we speculate that it may be common and therefore represent an unaccounted for component of the global electric circuit.