1944-8007/asset/olbannerleft.jpg?v=1&s=8efe58b4bccbbac51c9740677fc27dec62622c0b)
1944-8007/asset/olbannerright.jpg?v=1&s=4147b7adc92f6020ebf1ced4d118944fcf4a9a0b)
Atmospheric Science
Positive leader characteristics from high-speed video observations
Article first published online: 1 APR 2008
DOI: 10.1029/2007GL033000
Copyright 2008 by the American Geophysical Union.
Additional Information
How to Cite
, , , , , , , and (2008), Positive leader characteristics from high-speed video observations, Geophys. Res. Lett., 35, L07802, doi:10.1029/2007GL033000.
Publication History
- Issue published online: 1 APR 2008
- Article first published online: 1 APR 2008
- Manuscript Accepted: 12 FEB 2008
- Manuscript Revised: 25 JAN 2008
- Manuscript Received: 14 DEC 2007
Keywords:
- positive leaders;
- recoil leaders;
- speed;
- positive lightning
[1] 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 range 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.