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I'm trying to find what is true, what is myth and what is as yet

  1. Jun 28, 2011 #1
    I'm trying to find what is true, what is myth and what is as yet unknown about lightning.

    I've just read a great long spiel about how this proprietory lightning protector puts up a cloud of ionised gas to protect radio masts and such and claims results for named radio stations of say 12 strikes per year for say 12 years of history and then after the gee whizz protector is installed at great cost, no doubt, exactly zero strikes per year for the foreseeable future. Many examples given.

    I also read about more conventional lightning rods that supposedly direct strikes harmlessly to earth protecting everything within the subtended cone from the tip of 60 or 70 degrees. I have a photograph of a radio mast being struck half way down -- a cone of protection zero degrees wide?
    I also have a photo of a building in Chicago being struck right under the Sears Tower.

    Then I have read that the cloud leaders have no target "in mind" so to speak, and until the ground leader reaches out to it, are moving in random directions. Sort of begs the question of why they are heading towards the earth and not any other general random direction. Anyone know why these leaders seem to zig here and zag there? Perhaps random anomalies in the atmosphere they are encountering?

    Also, some folk claim to be able to neutralise the charge differential betwen the ground and cloud via coronal discharge (St Elmo's fire)
    And others say that this would be like trying to drain a lake through a drinking straw.

    I'm installing a weather camera about 20 feet above my roof on the end of what looks like a wooden yacht mast. It is WiFi connected, but there is a thin power cable from the camera to just below the roof line where a solar PV panel charged lead acid battery will be stowed.

    I originally thought I would need a heavy cable to the top of the mast and the 500 wires in this cable frayed out like a porcupine. I have the cable as well as a 15 foot length of copper pipe I was going to hammer into the wet sand of a drainage spot underneath. Seems maybe I don't need this, or it might cause more problems than not having anything?

    I'm certainly not in a heavy lighning area. I can only remember one fairly close ZAP in the 15 years I've been here.
    However, I don't want to attract problems.

    Can anyone shed any lighht on this subject, or point me to a good factual site.
    Regards, zapsukka
     
  2. jcsd
  3. Jun 28, 2011 #2
    Re: Lightning

    Hmmm. good question.
     
  4. Jun 29, 2011 #3

    Drakkith

    User Avatar

    Staff: Mentor

    Re: Lightning

    I think the leaders are reacting to the high voltage between the thundercloud and the rest of the environment. These leaders are simply paths of ionized air that extend out in different directions. The positive charge induced in the earth isn't very strong when these leaders are first produced, so they don't really have any particular direction to go. Once the leaders get close to an object on the ground they can induce a positive leader that comes up to meet them. The completed path then allows for the full discharge that is the main visible part of lightning.

    As for the rest, I cannot say really.
     
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