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Wednesday, July 22, 2009 - 12:35AM

Objective: Lightning under a microscope

By DAN ROBINSON

Editor/Photographer

So why all the talk about shooting upward (ground-to-cloud) lightning? Maybe this will shed some light. Upward lightning from towers is the only type of lightning that is predictable enough to capture at close range, since you know exactly where (and approximately when) it will strike. The following photos are 200% crops of three discharge events at the WVAH tower that I captured last year on June 3. (Click on the images to view the 200 percent-sized crops).

click to enlarge

Even in these images, you can see things going on that I think are only the beginning of what could actually be happening there. In addition to the bright main channel, you can see bigger leaders extending from the tower top, but also many more smaller and fainter channels emanating from various points. In the last image, there are colors and shapes in the decaying channel that I'd never seen before. The square-shaped lightning conductor on the top of the tower is around 4 to 5 feet wide, which gives you an idea of the scale of the features visible.

Curiosity and amazement at what I see here is driving me to want to go farther. My goal with the upward lightning documentation project is to put natural lightning 'under a microscope' in as much of a literal sense as I can. Imagine if those 200 percent crops above could be actual size and at twice the resolution or more - that is my next step! I hope to have a new lens configuration ready for the next upward lightning shoot that is capable of accomplishing that. Ultimately I'd like to be able to get close enough so that either a leader or a lightning channel fills the entire frame. That may be years away - but is something I'm working toward.

Sorry if this is a daft question Dan, but why does the bolt bend at 90 deg before it hits ?
- Posted by Mick from UK

Mick, the leader paths are pretty erratic as it is - the air is pretty 'uneven' when it comes to electrical resistance. The lightning just takes the easiest path, which is why there are so many kinks and bends. In this case, the sharp bend is caused by the wind pushing the channel sideways so far that it has to 're-connect' via a small new channel straight down from the first. In the first image, you can see the old channel fading out and drifitng away to the right, while the new section goes straight down to the tower. I've coined this the 'oxbow effect', since it is similar to how rivers behave when a sharp bend in the channel gets bypassed with a new shortcut.
- Posted by Dan R. from Charleston, WV

Thanks Dan !!
- Posted by Mick from UK