| Autor: |
Silva, C. L., Winn, W. P., Taylor, M. C., Aulich, G. D., Hunyady, S. J., Eack, K. B., Edens, H. E., Sonnenfeld, R. G., Krehbiel, P. R., Eastvedt, E. M., Trueblood, J. J. |
| Zdroj: |
Geophysical Research Letters; September 2023, Vol. 50 Issue: 17 |
| Abstrakt: |
The dissonant development of positive and negative lightning leaders is a central question in atmospheric electricity. It is also the likely root cause of other reported asymmetries between positive and negative lightning flashes, including the ones regarding: stroke multiplicity, recoil activity, leader velocities, and emission of energetic radiation. In an effort to contrast lightning leaders of different polarities, we highlight the staggering differences between two rocket‐triggered lightning flashes. The flash beginning with upward positive leaders exhibits an initial continuous current stage followed by multiple sequences of dart leaders and return strokes. On the other, in its opposite‐polarity counterpart, the upward development of negative leaders is by itself the entire flash. As a result, the flash with negative leaders is faster, briefer, transfers less charge to the ground, has lower currents, and smaller spatial extent. We conclude by presenting a discussion on the three fundamental leader propagation modes. Lightning flashes that carry positive and negative charges are completely different. In this article, we report on lightning triggered by launching a rocket tethered to the ground toward an electrified cloud. The staggering differences between positive and negative flashes are exposed by a three‐dimensional radio location system and by the current transferred to ground via the trailing wire. Triggered flashes with positive and negative leaders are contrastingly different with the latter being faster, briefer, and more compactThe channel behind triggered positive leaders decays engendering dart leaders and return strokes, which is unparalleled in the negative caseAverage conductivity is higher in the negative leader channel despite the lack of return strokes and the lower charge transferred to ground Triggered flashes with positive and negative leaders are contrastingly different with the latter being faster, briefer, and more compact The channel behind triggered positive leaders decays engendering dart leaders and return strokes, which is unparalleled in the negative case Average conductivity is higher in the negative leader channel despite the lack of return strokes and the lower charge transferred to ground |
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