Monday, July 17, 2006

A bolt of lightning...

Lightning forks across the sky today, thunder rumbles through the nearby canyons.

Read some interesting notes about lightning here.

Are you worried about being struck during a lightning storm? Consider what might happen to swimmers in the water.

Current from a lightning strike will follow the path of least resistance within the area of potential to ground. A human swimmer in open water would probably not intersect such a low-resistance path, except in rare circumstances.

Not so with a person in the bathtub of water. Plumbing fixtures in houses tend to be good conductors of electricity, and might carry electrical potential right down to ya! If you happen to be right in the way, some of the current will pass through you. (Electrifying thought!)

But the bottom line is, the path of a lightning strike is impossible to predict -- no matter where you are standing.

A number of years ago, I was in the middle of a brief but violent thundershower while we were boating on Lake Havasu. In anticipation of strong winds and big waves, my dad and I anchored our boat in deep water offshore. When the storm hit, there were numerous lightning strikes all around us--it literally lit up the sky for a period of half an hour.

However, as far as I could tell, most of the strikes hit on the sand dunes and hills around the lake. Few of them hit the water. I did not spot any dead fish.

The group of our young scouts were not as prudent in their choice of ground to weather the storm. Several of them could be seen scampering across the tops of nearby dunes, with bolts of lightning detonating all around them -- one of even pausing to water the weeds, in defiance or ignorance, or just responding to the urgency of the moment, I cannot tell. Though we thought they looked like prime targets for flash-barbeque, amidst the all the roaring and flashing, none of the scouts were harmed.

I understand this capriciousness of lightning is presumed to be due to the localized accumulation of electrical potential that causes a lightning strike. It may well be that there is a better conductor nearby, but the location of the highest potential seems to be a bigger factor. Among the lightning folk tales we hear so often, some suggest that some type of insulation from the ground, like rubber tennis shoes, may provide a safety factor. But this seems a rather pitiful provision, considering that the electrical charge may have already passed through miles of air, which is a very good insulator.

If you do happen to provide a convenient ground conductor for one of these frightful bolts from the blue, just remember, there is still hope. In wilderness first aid training I learned that the most common outcome from being struck by lightning (other than flash burns) is cardiac fibrillation.

The electrical discharge through the body disrupts the electrical rhythm of the heart pacemaker, with the result that the heart muscles lose their coordinated pumping action, and just flutter ineffectually. Reportedly, CPR can be very effective in sustaining the life of a person in this condition. Ideally, an AED can be used immediately to restart the heart rhythm.

The American Heart Association has recently published new guidelines for CPR and the application of AED devices.

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