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Observations of corona in triggered dart‐stepped leaders
Author(s) -
Gamerota W. R.,
Uman M. A.,
Hill J. D.,
Jordan D. M.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl062911
Subject(s) - corona (planetary geology) , lightning (connector) , dart , physics , lightning strike , corona discharge , geology , meteorology , astrophysics , optics , thunderstorm , voltage , computer science , power (physics) , quantum mechanics , astrobiology , venus , programming language
Corona streamers are a critical component of lightning leader step formation and are postulated to produce the very high electric fields at their tips that produce runaway electrons resulting in the observed X‐ray bursts associated with leader stepping. Corona emanating from the vicinity of the leader tip between leader steps was analyzed using three sequential high‐speed video sequences of dart‐stepped leaders in three different triggered lightning flashes during the summers of 2013 and 2014 in northeast Florida. Images were recorded at 648 kiloframes per second (1.16 µs exposure time, 380 ns dead time) at an altitude of 65 m or less. In each image sequence, the leader propagates downward in consecutive frames, with corona streamers observed to fan outward from the bright leader tip in less than the image frame time of about 1.5 µs. In 21 exposures, corona streamers propagate, on average, 9 m below the bright leader tip.