Luminous pulses during triggered lightning
| Autor: | Kenneth B. Eack, G. D. Aulich, S. J. Hunyady, E. M. Eastvedt, W. C. Murray, Harald E. Edens, William P. Winn, J. Trueblood |
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| Rok vydání: | 2012 |
| Předmět: |
Atmospheric Science
Soil Science Astrophysics::Cosmology and Extragalactic Astrophysics Aquatic Science Oceanography Electromagnetic radiation Superposition principle Optics Geochemistry and Petrology Negative charge Earth and Planetary Sciences (miscellaneous) Astrophysics::Solar and Stellar Astrophysics Main channel Astrophysics::Galaxy Astrophysics Earth-Surface Processes Water Science and Technology Video recording Physics Ecology business.industry Paleontology Forestry Short distance Geophysics Electric power transmission Space and Planetary Science business Vertical field |
| Zdroj: | Journal of Geophysical Research: Atmospheres. 117 |
| ISSN: | 0148-0227 |
| DOI: | 10.1029/2011jd017105 |
| Popis: | [1] A triggered lightning flash that transferred negative charge to ground in central New Mexico produced more than three levels of branching above the main channel to ground in a 1 km vertical field of view. A high-speed video recording shows that the main channel had about 50 brief luminous pulses, many of which were superimposed on a slowly changing persistent luminosity. In contrast, superposition was rare in the uppermost visible branches because luminous pulses first appeared on preexisting dark channels before merging into a luminous channel. This observation suggests that luminous pulses in triggered and natural lightning originate only on dark branches and that the complexity of the main channel to ground is the result of multiple mergers of dark branches with pulses into luminous branches without pulses. This suggestion is contrary to an earlier conclusion that there are two kinds of luminous pulses. We also observe behavior characteristic of electromagnetic waves on transmission lines: when a downward propagating luminous pulse reaches a junction with another initially dark branch, it travels both upward and downward along that branch. Upon reaching the ground the downward propagating wave produces a bright reflection which also splits at the junctions, producing luminosity for a short distance upward in one direction while propagating much farther upward along the path charged by the downward propagating wave. However, when a downward moving luminous pulse reaches a junction with an initially luminous branch, splitting is not evident, probably due to the greater conductivity of the luminous channel. |
| Databáze: | OpenAIRE |
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