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Lightning Safety Facts

Backpacking and camping basics and other general trip planning discussion for the uninitiated. Use this forum to learn where to look for the information you need, and to ask questions, related to the beginner basics of backpacking and camping, including technique and best practices.
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Re: Lightening Safety Facts

Postby toejam » Fri Jul 27, 2012 9:30 am

I think it is important to remember that many more people are killed or injured falling than being struck by lightning. If you are caught in a thunderstorm, be extra careful with your footing.

My favorite lightning facts are the stats:

http://www.lightningsafety.noaa.gov/statistics.htm


Lightning is many thousands of volts traveling several miles through the atmosphere in excess of the speed of sound. Therefore, it often misses the points it is theoretically most likely to hit. I've never seen stats that suggested someone's hiking or tent poles caused them to be struck. I don't think a bolt of lightning would notice. If you are caught outdoors in a thunderstorm you can only slightly improve your odds of not getting struck, but fortunately the odds are greatly in your favor.



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Re: Lightening Safety Facts

Postby giantbrookie » Fri Jul 27, 2012 10:35 am

toejam wrote:I think it is important to remember that many more people are killed or injured falling than being struck by lightning. If you are caught in a thunderstorm, be extra careful with your footing.

Yes, this is a very important point. I have not seen the statistics, but I'd be willing to hazard a guess that there is a bigger killer than slip and fall associated with thunderstorms: this would be hypothermia. Many folks hiking in the summer months do not bring adequate clothing for wet weather and getting doused in a rainstorm can lead to trouble in a hurry. This can be a problem even if a person is not lost, but the problem is compounded if someone is lost (poor visibility during the downpour may aid in this) and in a place where nobody can help them. I recall a disastrous Labor Day weekend (I believe--it's been a long time) in the 70's or early 80's when there were multiple hypothermia deaths in the High Sierra owing to folks being caught in rainstorms.
Since my fishing (etc.) website is still down, you can be distracted by geology stuff at: http://www.fresnostate.edu/csm/ees/facu ... ayshi.html
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Lightening Safety Facts

Postby themappist » Mon Jul 29, 2013 6:01 pm

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Re: Lightening Safety Facts

Postby SSSdave » Wed Jul 31, 2013 12:43 pm

http://www.vaisala.com/Vaisala%20Docume ... Gookin.pdf

The article has considerable useful information. However for such a serious attempt at outdoor lightning protection I was surprised at how little actual new information was about being outdoors in actual landscapes. Most of what they noted is somewhat old news. I could write several pages here but the below will suffice. At the top of the article is the statement:

"Most ground strikes occur below the cumulonimbus cloud, but many still strike beyond the shaft of rain or beyond the edge of thecloud. This is important for lighting safety since it doesn’t need to be raining or even cloudy overhead for you to be in danger from lightning."

And then that is the last such is mentioned. Even though they have a significant section on how step leaders work, they don't bother connecting the reality that step leaders tend to be much closer to the ground wherever rain is falling especially heavy rain because electrolytes in water make it far more conductive than even humid air. Most outdoor people, especially Easterners understand through experience that the nastiest closest lightning tends to occur during initial onset of heavy rains when a front arrives. Also with thunderstorms of course, where rains fall, towering cumulus clouds above contain most of the positive charge that is seeking the negative electrons down on the ground. Thus when outdoors after one hears thunder in the distance then somewhat later feels the first drops of water, one ought immediately get alot more serious about seeking the best local area for protection because those step leaders are likely to then be much closer to the ground.

The article also did not have much new to say about best places to stay in terrain other than avoiding tall objects. For instance trees are not always a poor choice...if they are within a dense forest and one is not beneath or near one of the taller trees. In fact the dried leaf matter below many conifers is an excellent insulator across which lightning is not likely to flow. Any lightning hitting tallest trees in a forest on deeper soils is more likely to follow the main trunk down into the ground and then expand out beneath the ground. Of course such places below tree canopies are also certain to be more pleasantly drier during rains. Find spots that while under leaf canopies are not directly adjacent to any larger trunks.

In granite geology, bedrock tends to be broken up into regular joint cracking. Some are wide enough to fit a truck while many others are rock touching rock. Inside those narrower cracks is all matter of plant roots, soil, and moisture. Lightning ground currents are more likely to follow such joint cracks versus other areas of bedrock because the resistance is likely less. So don't make your stand over a narrow joint crack. In granite geology there are often flat coarse granite sand areas aka gruss flats, between bedrock that are well drained and relatively dry versus other soils. Good places to pitch a tent on. Lightning ground currents tend to flash spreading over the surface of wet bedrock are likely to go around such sand.

In uneven mountainous landscapes, the safest areas tend to be at the base of steep slopes (not small slopes). But perferably in dry areas thus not where seeps come out. Those areas also are more likely to have talus that often has ready places to get beneath and place gear out of rain. So storms are brewing and you have some time to move about in the local landscape? Head to the base of talus slopes.

An area to avoid is landscape knees. Say there is flat terrain that drops off at a knee down to lower areas. Stay well away from such knees even though they may not stick up like a tree, if a step leader up in the air is moving across from the lower areas towards the knee, as soon as it meets the knee it may draw streamers up and complete the path causing bolts.

Another strategy to be significantly more safe is to carry a super light plastic trash bag like this that one:

http://www.thenerds.net/GENUINE_JOE.Gen ... 04046.html

that one can totally get inside while stooping in the lightning position per the article. However the bag needs to be like new WITHOUT ANY PIN HOLES. This will make your otherwise very conductive body seem to be a far higher electrical path versus anything adjacent so any lightning air or ground currents are likely to go around you. One bag is less than an ounce and takes up little space.

David
http://www.davidsenesac.com
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Re: Lightening Safety Facts

Postby ERIC » Wed Jul 31, 2013 7:29 pm

Cross post here: viewtopic.php?f=35&t=9749 I locked that thread since it redirects to this one.
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