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Optical progression characteristics of an interesting natural downward bipolar lightning flash
Author(s) -
Chen Luwen,
Lu Weitao,
Zhang Yijun,
Wang Daohong
Publication year - 2015
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2014jd022463
Subject(s) - lightning (connector) , stroke (engine) , flash (photography) , ranging , physics , meteorology , optics , astrophysics , geology , geodesy , power (physics) , quantum mechanics , thermodynamics
Abstract Using high‐speed cameras, Lightning Attachment Process Observation Systems, and fast and slow electrical antennas, we documented a downward bipolar lightning flash that contained one first positive stroke with a peak current of 142 kA and five subsequent negative strokes hitting on a 90 m tall structure on 29 July 2010 in Guangzhou City, China. All the six strokes propagated along the same viewed channel established by the first positive return stroke. The leader which preceded the positive return stroke propagated downward without any branches at a two‐dimensional (2‐D) speed of 2.5 × 10 6 m/s. An upward connecting leader with a length of about 80 m was observed in response to the downward positive leader. The 10–90% risetimes of the return strokes' optical pulses ranged from 2.2 µs to 3.2 µs, while the widths from the 10% wavefront to the 50% wave tail ranged from 56.5 µs to 83.1 µs, and the half peak widths ranged from 53.4 µs to 81.6 µs. All the return strokes exhibited similar speeds, ranging from 1.0 × 10 8 m/s to 1.3 × 10 8 m/s. Each of the return strokes was followed by a continuing current stage (CC). The first positive stroke CC lasted more than 150 ms, much larger than all the subsequent negative stroke CC, ranging from 13 ms to 70 ms.