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The Safest Thing to Do On an Open Field During Lightning

  1. Jul 12, 2015 #1
    As in the the title, what to do if caught in an open field during a sudden lightning storm. Have heard conflicting recommendations from laying flat to squatting in two feet. Trying to avoid being part of the return strike which would not be pleasant at all.
     
  2. jcsd
  3. Jul 12, 2015 #2
    Two mechanisms at work here.
    1) For a direct strike, it is thought that strike locations are random, say 1 strike per sq km per year, but tend to be drawn to an object over a radius equal to its height. So if you halve your height, the area over which you might draw a strike is then a quarter.
    2) When the strike hits the ground, very large currents flow outwards in the ground and create a voltage gradient across the ground. This gradient can drive a current through an animal whose legs are at different points. Four legged animals are more at risk than man, as the voltage is greater due to the spacing.
    For this reason, crouching low with feet together is recommended. Walking has the advantage that the feet are both in contact with the ground for a very small period. Other advice is to stay away from a long fence, which has a high statistical risk of being struck, and from a tree, which will have large ground currents and a risk of side flashing. As for removing metal objects, this is official advice but I am uncertain of the theoretical basis.
     
  4. Jul 12, 2015 #3
    @tech99. Your blog appears to be succinct and to the point with excellent examples and common sense. I will leave this string open for a while but really don't anticipate a better or more informative reply than yours. The only question I have is that if my height is six feet, half my height is three feet and then? Are you saying that a direct strike would be more likely if I were three feet wide? I don't understand that part of your reply. The second part is crystal clear.
     
  5. Jul 12, 2015 #4
    Thank you Steve. If an object, such as a pole, is six feet high, then we expect it to collect lightning strikes from a ground area having a radius of six feet. If it is three feet high, then it will collect from a 3 ft radius. In the second case, the ground area is a quarter of the first, so by halving the height, the chance of a strike is quartered. If an object is wide, such as a building, then it is assumed that the capture area is the actual area, plus a surrounding margin worked out from the height, as I have described.
     
  6. Jul 12, 2015 #5

    Evo

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    To clear up misinformation about lightning stikes if caught in an open field.

    http://www.srh.noaa.gov/jetstream/lightning/lightning_faq.htm

    http://science.howstuffworks.com/nature/natural-disasters/lightning8.htm is a nice lengthy read.

    Why am I so interested in lightning? I have been struck 3 times, twice on a corded phone, where the phone was blown out of my hand and across the room, yes I suffered hearing loss which eventually returned. Once from plumbing. I saw the lightning hit in the yard and dirt fly up into the air. then I was getting into my car once and had just sat in the car and closed the door when the hair on my head and neck went up and the lightning hit a few yards away. My house was directly hit by lightning, had a small electrical wire fire in the walls, lost $10k in electronics, burnt out the power surge protectors too, yes I have threads about these when they happened which I wrote here years ago. The oldies here might remember my streaks of incredibly bad luck.
     
    Last edited: Jul 12, 2015
  7. Jul 12, 2015 #6

    davenn

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    But hey ... The good luck part is ... even after all that, you are still with us :)
    Thankfully


    Dave
     
  8. Jul 12, 2015 #7

    Evo

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    What? What was that you said sonny? Speak into old Evo's other ear.
     
  9. Jul 13, 2015 #8
    I personally don't think about it. About 25 people are killed each year in the USA by lightning. That's less than 1 person in 10 million.

    I don't live where Evo lives, so the odds for me must be near zilch.

    Having said that...fields are relatively safe. Nearly all lightning fatalities involve trees, roofs, etc. Yes lowering your stature may help... and having minimal ground contact. I doubt if there is any means of measuring any stats. However, it's all physics so Tech99's advice seems valid to reduce an unlikely event even more.

    Nobody in decades in my area has been killed walking in a field in a lightning storm.
     
  10. Jul 13, 2015 #9

    davenn

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    LOL

    I don't expect you to divulge, but I turn 56 in 3 days time. My "sonny" days are well behind me :wink:

    Dave
     
  11. Jul 14, 2015 #10
    My problem, @tech 99, is that have such a fat head, that lightning would hit it before it hit the ground. However, I think you have quite adequately answered this question and I have to contact Evo on how to close this thread. Mucho thanks for your help.
     
  12. Jul 14, 2015 #11
    @Evo. I know a woman (a red head, naturally) who has been struck by lightning three times. She is crazier than a hoot owl but I am positive that her craziness preceded her lightning strikes. She had to be that way as there is no earthly explanation as her complete lunacy, although the good news is that she is "nice crazy" and makes everyone around her laugh.. I think your hair rising up just prior to the lightning strike near you was the build up of static electricity from the ?streamer effect with like charges which repelled each other. We had a lightning strike some 20 feet from our house which blew out all the phones, the flat screen TV, an older computer. Fortunately, the TV was still on mfg. warranty, the phones were the responsibility of the cable company, and the computer I had to upgrade anyway, just forced me to do it a little earlier. You mention to avoid the lightning crouch position, but what do you do (I don't go outside during electrical storms) when you're stuck. Laying down is no good, crouching is no good. Anything good, other than prayer?
     
  13. Jul 14, 2015 #12
    @Evo. Then, in your understanding, what are the "positively charged particles" which travel upward (in the streamer) towards the stepped ladder? They are not electrons, they are not positrons. Maybe they are positively charged ions or atomic nuclei after their electrons have been stripped (plasma). Maybe it is the charge, not the actual particle that moves up much like a freight train initially pulls the last car but the train itself does not move the entire length of itself. Do I make sense now?
     
  14. Jul 14, 2015 #13

    Evo

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    I'm not a scientist, I've just always enjoyed science, but my dad wouldn't allow me to go into science, (long story), so I surrounded my self with people in science, not hard since I lived near NASA and studied on my own with their help. What I am now is a "googler". What I found is this, which I previously posted, perhaps someone here can explain in more detail.

    http://www.regentsprep.org/Regents/physics/phys03/alightnin/default.htm

    This was also interesting. http://www.physicsclassroom.com/class/estatics/Lesson-4/Lightning
     
    Last edited: Jul 14, 2015
  15. Jul 14, 2015 #14
    @Evo. It seems like the first if your references answers the questions: there it is stated:

    "
    • As the negative charges collect at the bottom of the cloud it forces the negative charges in the ground to be forced away from the surface. This leaves the ground positive.
    • A streamer of negative charges is repelled by the bottom of the cloud and attracted by the ground.
    • As this streamer of negative charges approaches the ground, a streamer of positive charges is repelled by the ground and attracted to the negative streamer.
    • When the two streamers connect, they have created a fairly conductive path which allows a sudden down surge of electrons to jump to the ground. This is the lightning.
    • The rapidly moving electrons excite the air along the path so much that it emits light. It also heats the air so intensely that it rapidly expands creating thunder.
    • One thing to notice is that the positive charges that make up both the cloud and the ground do not move. Even the positive streamer launched by the ground is really only made up of positively charged air particles because the electron(s) left the particle.
    The last bullet answers the question. It appears that a charge can move without (significant) movement of particles. But, BAM! When the streamer meets the stepped ladder, the electrons do move in the order of 10^5 mph while the electric field itself moves almost at the speed of light:
    https://www.physicsforums.com/threads/speed-of-electricity.322195/

    This was never very clear to me and most references, other than the few I have found and some others which were pointed out to me actually addressed this phenomenon. Sometimes the simplest question defies a simple answer, if any.
     
  16. Jul 20, 2015 #15
    SO apparently I found the best position - no everybody practice this.
    1-handed_peacock.jpg
     
  17. Jul 20, 2015 #16

    mfb

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    Above the ground, with a large cross-section, and if lightning strikes the whole current will flow through the arm. Does not look very safe. On the other hand, if you get struck, you can think "no problem, it's just in my head" - unless it actually was in your head, then you probably cannot think any more.
     
  18. Jul 29, 2015 #17
    She is s-o-o-o skinny - ugh!
     
  19. Aug 1, 2015 #18
    The odds of being hit by lightening, (from Aaron's comment ~1 in 10 million) when a large fraction of the population is indoors when it's raining, is too simplistic for me. The odds of being hit by lightening, when lightening is present, and you are outdoors, is a more useful statistic, and while I've never seen those odds, I wouldn't take the risk lightly (pun intended), and strongly suspect that it's much higher, or IMO, the odds of several commentators here having had experiences with lightening strikes would be statistically rather peculiar. Also, if you feel a static charge, run like heck; and for groups of people; run in as many different directions as possible so that if one person is hit, the others can be of assistance. I wonder if planting my aluminum walking stick in the ground just before I do the 400 meters, might improve the odds?
     
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