Pasko Victor P, Stanley Mark A, Mathews John D, Inan Umran S, Wood Troy G
CSSL Laboratory, Penn State University, University Park, Pennsylvania 16802, USA.
Nature. 2002 Mar 14;416(6877):152-4. doi: 10.1038/416152a.
For over a century, numerous undocumented reports have appeared about unusual large-scale luminous phenomena above thunderclouds and, more than 80 years ago, it was suggested that an electrical discharge could bridge the gap between a thundercloud and the upper atmosphere. Since then, two classes of vertically extensive optical flashes above thunderclouds have been identified-sprites and blue jets. Sprites initiate near the base of the ionosphere, develop very rapidly downwards at speeds which can exceed 107 m s-1 (ref. 15), and assume many different geometrical forms. In contrast, blue jets develop upwards from cloud tops at speeds of the order of 105 m s-1 and are characterized by a blue conical shape. 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.
一个多世纪以来，已经出现了许多未经证实的报告，讲述雷暴云上方出现的异常大规模发光现象。80多年前，有人提出放电可能会弥合雷暴云和高层大气之间的间隙。从那时起，人们在雷暴云上方识别出了两类垂直扩展的光学闪电——精灵闪电和蓝色喷流。精灵闪电在电离层底部附近产生，以超过107米每秒的速度非常迅速地向下发展，并呈现出许多不同的几何形状。相比之下，蓝色喷流以大约105米每秒的速度从云顶向上发展，其特征是呈蓝色锥形。但是，尚未有与精灵闪电或蓝色喷流相关的实验数据被报道，能够确凿地表明它们在雷暴云和较低电离层之间建立了电接触的直接路径。在此，我们报告一段在波多黎各阿雷西博天文台拍摄的视频记录，记录了一道蓝色喷流从雷暴云向上传播至约70千米高度的过程。在42千米以上的高度——通常是蓝色喷流的上限和精灵闪电的下限高度——该闪电呈现出一些通常在精灵闪电中观察到的特征。由于我们是在一个相对较小的雷暴单体上方观察到这一现象的，我们推测它可能很常见，并因此代表了全球电路中一个未被考虑到的组成部分。
