Path: utzoo!attcan!uunet!samsung!sol.ctr.columbia.edu!cica!iuvax!daemon
From: commgrp@silver.ucs.indiana.edu (BACS Data Communications Group)
Newsgroups: sci.electronics
Subject: Re: precipitation static
Message-ID: <52707@iuvax.cs.indiana.edu>
Date: 31 Jul 90 14:53:23 GMT
Sender: daemon@iuvax.cs.indiana.edu
Lines: 44

davet@tsdiag.ccur.com (Dave Tiller N2KAU) writes:

>Amen to the increase in static potential when snowing!!  I got the 
>BeJesus shocked outta me when I reached over to tune my 10m Amateur 
>radio whilst traveling on a _metal_ suspension bridge (Del. Mem).  I 
>figured at the time the snow added to the static buildup by imagining 
>all of those snowflakes hitting my antenna and losing electrons as 
>they slipped past.  Ouch!!!

I once flew a kite on steel wire-recorder wire (very strong and light; 
NOT recommended near power lines!)  The sky was cloudless, but I got 
strong shocks from the wire spool.  I presume that charge was building 
until there was sufficient voltage to discharge through my rubber shoe 
soles.

Precipitation static (a mild form of St. Elmo's fire?) causes radio 
interference in vehicles, especially aircraft.  Ever notice the 
flexible wicks attached to the trailing edges of aircraft wings?  
Those are for dissipating precip. static.  Not all planes have them; 
my flight instructor once remarked that precipitation static is worse 
in Piper Cherokee-class aircraft than in Cessna 172's.  That's 
probably because the trailing edges of Cessna wings are corrugated and 
have sharp points, whereas Pipers are smooth.

I encountered precipitation static while driving through a blizzard in 
S. Dakota--  I heard a popping sound (about twice per second) and 
looked inside the hole in the dash where the radio had been removed.  
I saw sparks jumping across the end of the antenna connector.  The 
sparks stopped after about two minutes and did not recur, even though 
the snow intensity did not diminish.

I've also seen CB (AM) radio interference while driving in snow or 
rain in mountains:  Noise builds up in the radio, then abruptly stops 
as the static discharges to ground (across the tires?); then the cycle 
repeats.

_Popular Electronics_ magazine in the '60s published an article about 
an electrometer for monitoring atmospheric voltage.  It was a pentode 
tube with a grid cap, on which was mounted a circular metal plate 
about 8 inches diameter.

--

Frank Reid   W9MKV   reid@ucs.indiana.edu