Observations of the Conversion of a Lightning Negative Stepped Leader into a Lightning Positive Leader
Abstract
We present observations of an unusual cloud-to-ground lightning flash that consisted of the conversion of a decaying side branch of an initial negative cloud-to-ground lightning stroke into a branched positive leader and subsequent positive cloud-to-ground return stroke. Observations were made with a Photron SA1.1 high-speed video camera operating at 36,000 frames per second, fast optical sensors, a flat-plate electric field antenna covering the SLF to MF band, and VHF and UHF radio receivers with bandwidths of 20 MHz. Following the initial negative cloud-to-ground return stroke, continued discharge activity resulted in a dart leader that traversed the central channel of the decaying negative stepped leader branch and then terminated. Approximately 1.5 milliseconds upon termination of the dart leader, the channel became progressively more luminous until it simultaneously formed multiple propagating positive leader branches. The lower-most of these branches propagated toward the ground until one of them attached and caused a positive return stroke.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMAE13B0359P
- Keywords:
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- 3304 ATMOSPHERIC PROCESSES Atmospheric electricity;
- 4301 NATURAL HAZARDS Atmospheric