Re: Lightning Safety
Norman J. MacLeod (gaelwolf@MARLIN.SSNET.COM)
Tue, 6 Jun 1995 22:36:39 EDT
I'll add in my two cents about lightning, since I have had more than one
experience with being close to it. Pretty powerful stuff, even if it doesn't
come close enough to kill you!
If you are backpacking or hiking, get off the ridges, and don't hang about
under lonely trees, especially those scraggly ones that have strips of bark
hanging off next to old scars!
I was part of a backpacking group about 25 years ago, when we were overtaken
by a summer thunderstorm while we were on a rocky ridge-line. (It had been a
very hazy day, and there was no way to see it coming soon enough to go an
alternate route). As it was readily apparent that there was no way we were
going to be able to make it to the end of the ridge, we shucked our packs
and placed them in a "safe-ish" area. Taking our raingear and groundpads
with us, we got off the ridge-line over the shoulder of the mountain to a
point where we couldn't go any further, and hunkered down for a real
splash-banger of a storm. Once the storm had passed and the sun came out
again, we went back to our packs. Things were pretty much alright, with the
sole exception of one pack that had had a half-full aluminum canteen inside.
Lighting HAD danced along the ridge, and the pack got zapped. The water into
the canteen had turned into superheated steam, and exploded the canteen.
Aluminum shrapnel then went through clothing and a down sleeping bag. Poor
guy spent the rest of the trip looking as if he had been attacked by
super-moths, and seemed to constantly sprout little puffy bits that wafted
away on the gentlest of breezes.
Lightning takes the path of least resistance to the ground. Since air is a
very poor conductor, lighting seeks anything better - and an upright human
being is far better for its purpose than air! Stick up above the grass and
trees while hiking, and you become a prime target. The main trick is to
prevent lighting making a path to ground through your heart. That's why you
should take a groundpad or your daypack and put it between you and the
ground itself as a layer of insulation.
Don't sit on the ground or the groundpad. (You don't really want the thrill
of a high-voltage charge moving from one buttock to the other through your
abdomen...) The soles of your shoes will help insulate you from the ground,
so you should crouch down on your feet on top of whatever supplementary
insulation you have and ride out the storm. If you are on a rock-climbing
trip, a coiled rope works well. (Ask me how you feel when you are on a long
high-angle pitch and your equipment starts to buzz and spark sometime...)
While you might think that overhanging ledges and superficial surface caves
close to the top of a mountain are good places to seek shelter, let me give
you something else to think about! Most of these "shelters" were made by the
geologic forces induced by glaciers and earthquakes, rather than by the
water action that forms deep caverns. The forceful geologic processes place
great stress on the bedrock structure, and frequently result in the
formation of numerous cracks. These cracks provide an often wet pathway of
lower resistance than the surounding rock. The consequence can then be a
situation where lightning jumps across the gap between the floor and the
roof, rather like the gap in a sparkplug. If you've never considered this
before, you are far from alone. It never really came home to me until I had
to go out on a SAR-OP and help bring someone back from the mountains who met
his Maker this way.
When you are setting up a campsite in the summer-time, keep thunderstorms in
mind. Don't pitch your tent close to the larger trees in the area, since
these are the ones sought after by lighting. Be especially careful to avoid
trees that have long vertical notches in their trunks, or have long, narrow
strips of bark peeled from the trunk. When lighting hits a tree, most of its
force travels down the moist area between the bark and the wood of the
trunk. The bark gets stripped off when the resulting stream forces its
escape, and the narrow vertical notches come about as the tree heals over
the following years.
When lighting hits a tree, it then tends to follow the tree's roots, which
is why people don't have to be standing directly under a tree to get knocked
over by the lighting. This secondary stike zone's size depends on the
species of tree, with hardwoods generally having a wider area of risk.
Lighting can easily disrupt the electrical signals that make your heart work
properly. The only saving grace here is that CPR is far more likely to be
successful on a lightning victim than on the victim of a severe heart attack.
All that aside, I still enjoy a good old rip-snorter of a thunderstorm, even
if I am out in it. There's something very exciting about being close enough
to nature to be able to feel a part of the storm...
Terry Howerton Sakima Group, Inc. SCOUTER Magazine Kansas City