Re: [Paddlewise] Anyone understand lightning?

I visited the Boston Museum of Science on June 9 with a large group of my 
students. While there some of us attended one of the lightning "shows." A 
scientist/lecturer encamped himself in a metal cage during his talk and 
controlled large Van De Graaff generators, out of which emanated a million 
or more volts of electricity. Thus, simulating something like lightning and 
directing the charge to his cage, he demonstrated that a metal cage 
actually protects one during a lightning storm. His explanation was that 
the deadly charge actually travels around the outermost and outside layers 
of the cage, literally the outermost layer of atoms with their accompanying 
electrons. He proceeded to touch the inside of the metal cage while again 
"enduring" the huge voltage.

There may be practical benefits we can learn from this. Our scientist 
explained that rubber tires on a car are not what protect people from 
lightning. They do not "insulate" occupants as is commonly believed. It is 
actually the metal cage of the car! Furthermore, he warned people not to 
stick body parts outside the window during the storm. This would negate the 
protection. I really found this interesting!.

Also, while living in the Anchorage, Alaska area (1974 to 1996), I knew of 
a lady who was killed while jogging through a metal culvert (common on our 
biking/ski trails). Though I think the electricity that charged the culvert 
was of AC type (a broken power line?), the lady bolted into standing water 
on the floor of the culvert to rescue her dog, who had preceded her during 
her run and was being electrocuted. Perhaps this is not directly related to 
this discussion, but I am reminded of this while paddling in one of our 
nearby Maine lakes, where a road culvert leads to a boat ramp. My wife and 
I remained outside the culvert during a hummer of a storm last year, rather 
than paddle our boats lickety-split to the ramp to beat the storm. We got 
drenched by the side of the lake, but were perhaps safer than testing our luck.

Of further interest is the fact that sodium ions in salt water will easily 
conduct a charge of AC current, while distilled water will not. Of course, 
none of us paddle in distilled water :) But there are plenty of metal ions 
of various types in ground water in any discharge area (lake, river, 
household taps, etc.). I wonder, does this make salt water a bit more 
deadly to be on or in during a lightning storm?

Thanks,

Tom LeTourneau
Wells, Maine

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