Hi Ralph,Frame Untitled_20040802_1_frame_0067.jpg (frame 67) looks like a ghost image. Unfortunately, the following frame does not show details of the actual lightning strike, but I suspect that its shape would be identical to the channel in the frame 67. If frame 67 showed an actual upward leader, it should be clearly attached to an object below instead of seemingly being suspended in midair. The top of the discharge also looks artificially squared-off and truncated instead of being tapered to a point as in a real leader propagating leader.
The leader also looks considerably longer than typical ground-based positive leaders. The enhanced E-field from an approaching descending negative leader stimulates the formation of upward positive leaders from nearby ground-based objects just before the final jump. However, an E-field sufficient to generate a leader this long would likely generate other leaders from higher objects nearby. Although long positive leaders can be initiated from grounded objects without the need for a descending negative leader, these are launched only from relatively high objects such as antennas, tops of skyscrapers, or mountain tops.
Bert
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sparks@xxxxxxxxxxxxxx wrote:
(Long delayed reply...)It looks like you may be seeing artifacts from the camera's optical system or (more likely) the camera sensor and electronics. These "ghost" artifacts often show up when electronically photographing bright sparks or lightning.Another interesting flash happened a few years ago and I happened to see it. This sequence was captured by a traffic camera operated by WVUE-TV, New Orleans, Louisiana. I saved the video frames that day and have then online for you if you want to waste a few minutes. They are available at: http://w5jgv.com/special/lightning/ The individual frames are in sequence. The .ZIP file contains all the frames in case you want to download them for further inspection. Notice the ghost flash in the second frame. Thos flash is visible one frame (1/30 second) before a bright flash that occurs in the following frame. Is this a real leader flash or a ghost image? The remainder of the sequence shows a multi-flash cloud to ground strike several miles away from the camera. 73, Ralph W5JGV - WD2XSH/7 _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
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