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From: gsteckel@vergil.East.Sun.COM (Geoff Steckel - Sun BOS Software)
Newsgroups: sci.physics,sci.electronics
Subject: Re: St Elmo's Fire (was Re: Lightning)
Summary: Europeans put balls on lightning rods
Keywords: Induction, space charge, capacitance, and bulldrops ?
Message-ID: <2265@east.East.Sun.COM>
Date: 22 Jul 90 02:58:25 GMT
References: <1990Jul18.111525.5749@ioe.lon.ac.uk> <2436@speedy.mcnc.org> <1990Jul19.210925.165@mlb.semi.harris.com> <1047@tsdiag.ccur.com>
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Reply-To: gsteckel@vergil.East.Sun.COM (Geoff Steckel - Sun BOS Software)
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Organization: Omnivore Technology, Newton, Mass. (617)969-3448
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As an aside to the discussion of lightning conductors and fields:

Several articles (including one in Wireless World about 4 years ago)
noted that the necessity and efficacy of the `sharp point' of a traditional
lightning rod is disputed.  The USA style lightning rod has a sharp point,
but in Europe, a (small, 1-5" or 2-12 cm.) round ball is considered more
effective.  I can hypothesize a number of reasons for each one being effective:

  Points give higher field strength (but at >> 1 MV, does this matter?!)

  Balls give more surface area, and up to the point that field strength
  goes below some value, therefore give more local ionization.

Does anyone have any more information or references?

	geoff steckel (gwes@wjh12.harvard.EDU)
			(...!husc6!wjh12!omnivore!gws)
Disclaimer: I am not affiliated with Sun Microsystems, despite the From: line.
This posting is entirely the author's responsibility.