Dan Robinson
I wondered if anyone has noticed this tendency with lightning channels to develop their own 'oxbow lake channels' after part of the primary channel is bypassed in favor of a more direct route.
This process is similar to an 'oxbow lake' formation on streams or rivers, where a river bypasses a longer section of its channel to follow a more direct path.
I noticed this on the tower lightning video from last week. You can see the new channels stretching vertically from the tower tip up a few feet to join the old channel, while the old 'oxbow' channels continue drifting away with the wind.
http://wvlightning.com/plains2005/june14head4.jpg
I also noticed on an old lightning photo I have from 1997 that shows an 'oxbow channel' that was bypassed in later return strokes:
http://wvlightning.com/asp/largesize/wv-72497a.jpg
It looks like the oxbow channels are bypassed when the main channel drifts or is stretched/moved by variations in localized air currents (eddies in the wind, etc). In the tower stroke cases, the wind was moving the channel so fast that its last few feet were becoming significantly stretched, until the next return stroke found a new, more direct route to the antenna tip to be the path of lesser resistance.
This process is similar to an 'oxbow lake' formation on streams or rivers, where a river bypasses a longer section of its channel to follow a more direct path.
I noticed this on the tower lightning video from last week. You can see the new channels stretching vertically from the tower tip up a few feet to join the old channel, while the old 'oxbow' channels continue drifting away with the wind.
http://wvlightning.com/plains2005/june14head4.jpg
I also noticed on an old lightning photo I have from 1997 that shows an 'oxbow channel' that was bypassed in later return strokes:
http://wvlightning.com/asp/largesize/wv-72497a.jpg
It looks like the oxbow channels are bypassed when the main channel drifts or is stretched/moved by variations in localized air currents (eddies in the wind, etc). In the tower stroke cases, the wind was moving the channel so fast that its last few feet were becoming significantly stretched, until the next return stroke found a new, more direct route to the antenna tip to be the path of lesser resistance.
