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32877[John Muir Trail] Re: Lightening reminder

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  • Chris
    Jul 9, 2013
      Ralph:

      I agree, it makes sense to prioritize responses. Those recommendation grades in your PDF are really interesting. Looks like seeking shelter is ranks pretty high, but the lightning position ranks pretty low.

      I'm no physicist, but I think that all things being equal, a conductive tent pole or hiking pole is going to be pretty risky in a lightning situation, especially if there is a sharp point at the top. I don't understand the physics exactly, but it is something like the way beer or champagne bubbles form on tiny scratches on the inside of a glass.

      Chris.

      --- In johnmuirtrail@yahoogroups.com, straw_marmot <no_reply@...> wrote:
      >
      > Thanks for that.
      >
      > I don't know the answer, but I think this question is worth asking:
      >
      > My concern is getting our priorities right. My understanding was that physical location relative to surrounding terrain/trees is the dominant risk factor - affects probability of being near a strike in the first place. Then, minimizing conductive materials in your immediate vicinity (metals, anything wet) - affects ground current transmission if a nearby strike does occur.
      >
      > Tent poles are pretty insubstantial, so although they obviously fall into the category of conductive materials in the vicinity, I'm questioning their real significance?
      >
      > If we start worrying too much about our tent poles,
      > (a) people with non-metallic tentpoles may be under the illusion that a dangerous tent position is in any way safe;
      > (b) people in safe well-considered positions with aluminium poles may worry unduly and put themselves in more danger by feeling that they need to move mid-storm.
      >
      > Also note that some carbon fiber is highly conductive (some is not).
      >
      > I'm not up to date on this stuff - I'm grateful for the prompt to go and read up on it afresh.
      >
      > Ralph
      >
      >
      >
      > --- In johnmuirtrail@yahoogroups.com, Barbara Karagosian <barbara@> wrote:
      > >
      > > From the NOLS backcountry lightning safety guide - I think there's a copy in the Yahoo JMT files.
      > >
      > >
      > > Tents may actually increase the likelihood of lightning hitting
      > > that spot if they are higher than nearby objects. Metal tent poles
      > > conduct ground current and may generate streamers. Use your
      > > understanding of terrain and lightning to select tent sites that
      > > may reduce your chances of being struck or affected by ground
      > > current. If you are in a tent in "safer terrain" and you hear
      > > thunder, you at least need to be in the lightning position. But if
      > > your tent is in an exposed location, such as on a ridge, in a
      > > broad open area, or near a tall tree, you need to get out of the
      > > tent and get into the lightning position before the storm starts,
      > > and stay out until it has passed. It would be wise to anticipate
      > > additional hazards of getting out of tents in the dark of night
      > > during a storm. Determine a meeting spot, have rain gear and
      > > flashlights accessible, and have a plan for managing the group
      > > during this time.
      > > In gently rolling hills the lower flat areas are probably not
      > > safer than the higher flat areas because none of the gentle
      > > terrain attracts leaders. Strikes are random in this terrain.
      > >
      > >
      > >
      > > On Jul 7, 2013, at 6:13 PM, straw_marmot <no_reply@yahoogroups.com> wrote:
      > >
      > > Could you substantiate the idea that the conductivity of tentpoles is a significant risk factor for lightning strikes? Is there some research that you're aware of, or can you tell me the source of the advice?
      > >
      > > many thanks
      > > Ralph
      > >
      > > --- In johnmuirtrail@yahoogroups.com, Jack Young <trail2nowhere@> wrote:
      > > >
      > > > Lightening can be a major problem in the Sierra. The best policy for lightening storms in the Sierra is:
      > > > 1) get over the passes before noon
      > > > 2) sit on you sleeping pad away from metal objects. DON'T get in your tent if it has metal poles.
      > > >
      > > > A while back a couple was fried in their tent at Bishop Lake right below Dusy Basin / Bishop Pass.
      > > >
      > > >
      > > > Best regards,
      > > > Jack Young
      > > > 530-219-7900
      > > >
      > > > Sent from an iPad 
      > > >
      > >
      >
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