DOI: 10.1002/2013JD020257
论文题名: Asymmetries in bidirectional leader development of lightning flashes
作者: Van Der Velde O.A. ; Montanyà J.
刊名: Journal of Geophysical Research Atmospheres
ISSN: 21698996
出版年: 2013
卷: 118, 期: 24 起始页码: 13504
结束页码: 13519
语种: 英语
英文关键词: bidirectional leader
; lightning
; lightning mapping array
; polarity
; potential well
; recoil leader
Scopus关键词: Bidirectional leader
; Lightning mapping array
; polarity
; Potential wells
; recoil leader
; Lightning
; atmospheric modeling
; cloud
; electric field
; identification method
; lightning
; photography
; polarization
英文摘要: Lightning flashes develop as a bidirectional tree, with a negative and a positive end propagating simultaneously into cloud charges of the opposite polarity. In recent years, this process has been modeled assuming that the bidirectional channel remains a zero-net-charge perfect conductor starting at the electric potential of its initial location. So far, both leader ends were treated identically. We summarize characteristics of bidirectional leader development of various lightning flashes registered by the Ebro 3-D Lightning Mapping Array at the east coast of Spain, supplemented by high-speed camera records. In order to follow the horizontal development of positive and negative leaders over time, a time-distance-altitude graph was designed, using the flash origin or a cloud-to-ground stroke as reference. The examples confirm that negative and positive leaders propagate at characteristic horizontal speeds (105 and 2·104 m s-1). The positive leader's low apparent speed corresponds to the phase when recoil processes are active. Very fast negative leaders (up to 8·105 m s -1) are detected in association with positive cloud-to-ground strokes. Negative leaders respawn repeatedly from the origin or as a retrograde negative leader at the positive branch. Positive leaders remain propagating throughout the flash or until reaching ground. We show that the velocity difference shifts the potential of the leader, increasing the gradient with cloud charge at the positive end while reducing it at the negative end. The positive section lowers its potential through retrograde negative leaders, eventually making it possible to emit a new negative leader into the upper positive potential well. Key Points Slow recoiling positive leaders are continuously active throughout the flash Negative leaders cease and respawn from origin or as retrograde recoil leader Leader potential theory applied to asymmetric speed explains observed features ©2013. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/63076
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Lightning Research Group, Electrical Engineering Department, Technical University of Catalonia, TR1, 056, Colom 1, Terrassa, Barcelona ES-08222, Spain
Recommended Citation:
Van Der Velde O.A.,Montanyà J.. Asymmetries in bidirectional leader development of lightning flashes[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(24)