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DOI | 10.1002/2017JD027016 |
Features of Upward Positive Leaders Initiated From Towers in Natural Cloud-to-Ground Lightning Based on Simultaneous High-Speed Videos, Measured Currents, and Electric Fields | |
Visacro, Silverio; Guimaraes, Miguel; Murta Vale, Maria Helena | |
2017-12-16 | |
发表期刊 | JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES |
ISSN | 2169-897X |
EISSN | 2169-8996 |
出版年 | 2017 |
卷号 | 122期号:23 |
文章类型 | Article |
语种 | 英语 |
国家 | Brazil |
英文摘要 | Original simultaneous records of currents, close electric field, and high-speed videos of natural negative cloud-to-ground lightning striking the tower of Morro do Cachimbo Station are used to reveal typical features of upward positive leaders before the attachment, including their initiation and mode of propagation. According to the results, upward positive leaders initiate some hundreds of microseconds prior to the return stroke, while a continuous uprising current of about 4A and superimposed pulses of a few tens amperes flow along the tower. Upon leader initiation, the electric field measured 50m away from the tower at ground level is about 60kV/m. The corresponding average field roughly estimated 0.5m above the tower top is higher than 0.55MV/m. As in laboratory experiments, the common propagation mode of upward positive leaders is developing continuously, without steps, from their initiation. Unlike downward negative leaders, upward positive leaders typically do not branch off, though they can bifurcate under the effect of a downward negative leader's secondary branch approaching their lateral surface. The upward positive leader's estimated average two-dimensional propagation speed, in the range of 0.06x10(6) to 0.16x10(6)m/s, has the same order of magnitude as that of downward negative leaders. Apparently, the speed tends to increase just before attachment. |
英文关键词 | upward positive leader continuous propagation of positive leader initiation of upward positive leader lightning currents and electric fields high-speed videos of lightning negative CG lightning |
领域 | 气候变化 |
收录类别 | SCI-E |
WOS记录号 | WOS:000419396500008 |
WOS关键词 | CACHIMBO STATION ; FLASH ; MORRO |
WOS类目 | Meteorology & Atmospheric Sciences |
WOS研究方向 | Meteorology & Atmospheric Sciences |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/32177 |
专题 | 气候变化 |
作者单位 | UFMG Fed Univ Minas Gerais, LRC Lightning Res Ctr, Belo Horizonte, MG, Brazil |
推荐引用方式 GB/T 7714 | Visacro, Silverio,Guimaraes, Miguel,Murta Vale, Maria Helena. Features of Upward Positive Leaders Initiated From Towers in Natural Cloud-to-Ground Lightning Based on Simultaneous High-Speed Videos, Measured Currents, and Electric Fields[J]. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES,2017,122(23). |
APA | Visacro, Silverio,Guimaraes, Miguel,&Murta Vale, Maria Helena.(2017).Features of Upward Positive Leaders Initiated From Towers in Natural Cloud-to-Ground Lightning Based on Simultaneous High-Speed Videos, Measured Currents, and Electric Fields.JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES,122(23). |
MLA | Visacro, Silverio,et al."Features of Upward Positive Leaders Initiated From Towers in Natural Cloud-to-Ground Lightning Based on Simultaneous High-Speed Videos, Measured Currents, and Electric Fields".JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 122.23(2017). |
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