At 06:44 AM 4/25/02 -0600, mcduffie@actcom.net wrote:
>On Thu, 25 Apr 2002 07:17:58 -0400, Scott Detloff K8DX wrote:
>
> > Inspection of the vertical this morning shows nothing out of the
> > ordinary.
> >
> > Any ideas?
I think K1MK may have been closest to the mark with the mention of St.
Elmo's Fire. I found the following explanation on the Scientific American
web site. Elsewhere, I think I have also read that it can be caused by
wind on a conductor. Either way, it seems to fit the facts...
"William Beaty is an electrical engineer who has designed numerous science
exhibits for museums. He is the creator of the Science Hobbyist web page
and is a member of the Mad Science Network.. He offers the following
explanation:
St. Elmo's Fire is a type of continuous electric spark called a "glow
discharge." You've seen it many times before, since it is almost exactly
the same as the glows found inside fluorescent tubes, mercury vapor
streetlights, old orange-display calculators and in "eye of the storm"
plasma globes. When it occurs naturally, we call it St. Elmo's Fire, but
when it occurs inside a glass tube, we call it a neon sign.
St. Elmo's Fire and normal sparks both can appear when high electrical
voltage affects a gas. St. Elmo's fire is seen during thunderstorms when
the ground below the storm is electrically charged, and there is high
voltage in the air between the cloud and the ground. The voltage tears
apart the air molecules and the gas begins to glow. It takes about 30,000
volts per centimeter of space to start a St. Elmo's fire (although sharp
points can trigger it at somewhat lower voltage levels.)
St. Elmo's Fire is plasma. A normal gas is composed of molecules. The
molecules are composed of atoms, which in turn are composed of electrons
and clusters of proton particles. If the electric force applied to each bit
of gas is greater than a certain level of voltage, it causes the electrons
and protons of the gas molecules to be pulled away from each other. High
voltage transforms the gas into a glowing mixture of separate proton
clusters and electrons. We call this mixture of particles by the name
"plasma," and it is conductive. It also fluoresces with light.
The color of the glow depends on the type of gas involved. If we lived in
an atmosphere of neon gas, then St. Elmo's fire would be red/orange, and
lightning would be white with orange edges. Our atmosphere is nitrogen and
oxygen, and this mixture glows blue/violet when exposed to high voltage
fields. If a neon sign tube was filled with nitrogen/oxygen instead of
neon, it would light up blue/violet rather than red/orange.
Is this phenomenon related to ball lightning? No one knows, because no one
knows what ball lightning is, and it might not be a spark at all. St.
Elmo's fire is sometimes mistaken for ball lightning. Among other
differences, ball lightning can drift around like a soap bubble, while St.
Elmo's Fire always remains attached to an object."
73, Pete N4ZR
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