Positive leader characteristics from high-speed video observations

Marcelo M.F. Saba, Kenneth L. Cummins, Tom A. Warner, E. Philip Krider, Leandro Z.S. Campos, Mauricio G. Ballarotti, Osmar Pinto, Stacy A. Fleenor

Research output: Contribution to journalArticlepeer-review

88 Scopus citations

Abstract

Based on analyses of high-speed video recordings of cloud-to-ground lightning in Brazil and the USA, the characteristics of positive cloud-to-ground (+CG) leaders are presented. The high frame rates permitted the average, 2-dimensional speeds of development along the paths of the channels to be resolved with good accuracy. The values rage from 0.3 to 6.0 × 105 ms-1 with a mean of 2.7 × 105 ms-1. Contrary to what is usually assumed, downward +CG leader speeds are similar to downward -CG leader speeds. Our observations also show that the speeds tend to increase by a factor of 1.1 to 6.5 as they approach the ground. The presence of short duration, recoil leaders (RLs) during the development of positive leaders reveal a highly branched structure that is not usually recorded when using conventional photographic and video cameras. The existence of the RLs may help to explain observations of UHF-VHF radiation during the development of +CG flashes.

Original languageEnglish (US)
Article numberL07802
JournalGeophysical Research Letters
Volume35
Issue number7
DOIs
StatePublished - Apr 16 2008
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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