Gene Fuller wrote:
Ionization threshold has nothing to do with "voltage". It has everything
to do with field strength.

Of course, static field strength implies energy which is
proportional to volts squared. Here's a quote from:

http://www.ce-mag.com/archive/1999/novdec/mrstatic.html

"A corona discharge is also called a silent discharge. It
may be maintained as long as the breakdown *field strength*
is exceeded in some region—that is, as long as the *voltage*
of the electrode or the *charge density* of the charged
insulator is high enough."

Just before the field strength is high enough to cause
ionization, the voltage between the electrodes can be
measured. I don't see how ionization could occur at
zero volts which you seem to imply is a possibility.
--
73, Cecil, http://www.qsl.net/w5dxp

Cecil Moore wrote:

wrote:

Cecil Moore wrote:

W8JI is confusing cause and effect.


....and Cecil is confusing himself.


Charged dust particles can *cause* corona but they
don't necessarily cause corona. If the air is not
ionized, corona is impossible.

The air always has ions in it. It's one of the
mechanisms by which the giant spherical capacitor
called "the Earth" discharges. Quit changing the
subject, Cecil.
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:
Cecil, if you're too chicken to do the experiment, just say so,
I'll understand.

I did the experiment and posted how to do it.
Here it is again: Bring one end of a dipole down close
to the system ground rod. Charge up a capacitor to 12v.
Discharge the cap between the end of the dipole and
the ground rod. That pop you hear is NOT corona.
--
73, Cecil, http://www.qsl.net/w5dxp

Tom Donaly wrote:
The air always has ions in it.

I hope you understand the difference between isolated ions
existing in the air and the air being ionized into a
conducting path. Isolated ions is not corona.
--
73, Cecil, http://www.qsl.net/w5dxp

Cecil Moore wrote:
Tom Donaly wrote:
Cecil, if you're too chicken to do the experiment, just say so,
I'll understand.

I did the experiment and posted how to do it.
Here it is again: Bring one end of a dipole down close
to the system ground rod. Charge up a capacitor to 12v.
Discharge the cap between the end of the dipole and
the ground rod. That pop you hear is NOT corona.
--
73, Cecil, http://www.qsl.net/w5dxp

Hmmm.

10uF capacitor charged to 12 volts = dust particle

How much charge can a dust particle hold as it moves through the air
Cecil? Does it eventually assume the potential of the air? Can I
substitute a dust particle for a 1pF capacitor? For a 10pF capacitor?
For ten farads?

Why would anyone tgink that proves anything?

On the other hand I've been a few feet away from antennas in an
undisturbed environment, and I've seen and heard the corna many times.

Cecil Moore wrote:
Gene Fuller wrote:
Ionization threshold has nothing to do with "voltage". It has
everything to do with field strength.

Of course, static field strength implies energy which is
proportional to volts squared. Here's a quote from:

http://www.ce-mag.com/archive/1999/novdec/mrstatic.html

"A corona discharge is also called a silent discharge. It
may be maintained as long as the breakdown *field strength*
is exceeded in some region—that is, as long as the *voltage*
of the electrode or the *charge density* of the charged
insulator is high enough."

Just before the field strength is high enough to cause
ionization, the voltage between the electrodes can be
measured. I don't see how ionization could occur at
zero volts which you seem to imply is a possibility.

Cecil,

Of course, static field strength implies energy which is
proportional to volts squared.

BZZZZT! More fractured physics.

Here's a hint. Voltage is often poorly defined since it requires a
reference. Very few physical phenomena depend on voltage as a primary
parameter.

I don't see how ionization could occur at
zero volts which you seem to imply is a possibility.

Huh?? Did I say that?


73,
Gene
W4SZ

wrote:
10uF capacitor charged to 12 volts = dust particle

Nope, 1uF cap charged to 12 volts = charge.

One charged dust particle = charge.

I've never said I have ever heard a single particle
discharge. It was someone else who said that. I agree
with the 2000 ARRL Handbook when they said it was
"almost continuous". I have certainly heard that
"hash-type noise" get worse with wind speed. I wish
I had made S-meter measurements.

"Precipitation static is an almost continuous hash-type noise
that often accompanies various kinds of precipitation, including
snowfall. Precipitation static is caused by rain drops, snowflakes
or even *wind-blown dust*, transferring a small electrical charge
on contact with an antenna."

But what I am saying certainly makes a lot more sense
than your implication that all particles have exactly
the same charge as all antennas.
--
73, Cecil, http://www.qsl.net/w5dxp

Gene Fuller wrote:
Voltage is often poorly defined since it requires a
reference.

Yes, and the web page reference provided a well defined
reference between two electrodes with known capacitance.
There is *always* a relationship between electric field
strength and voltage. I disagree that they are unrelated
as you implied.

I don't see how ionization could occur at
zero volts which you seem to imply is a possibility.

Huh?? Did I say that?

No, but you implied it when you said "ionization threshold
has *nothing* to do with voltage". Nothing is zero so you
implied an ionization threshold is completely unrelated and
independent of volts. Do you want to amend that statement?
Maybe: "The relationship between field strength and voltage
is sometimes difficult to determine."?
--
73, Cecil, http://www.qsl.net/w5dxp

"Reg Edwards" wrote
About 20 years ago I measured the charge produced on a 150-feet,
long-wire, end-fed inverted-L antenna, using a DC, 0 to 50
micro-amp,
moving coil meter.

======================================

The VLF capacitance to ground of the 30-feet high antenna is about
250 pico-farads. Total capacitance including the air-spaced tuning
capacitor = 550 pico-farads.

Assuming a capacitor breakdown voltage of 2000 volts and a breakdown
rate of once per second, then leakage over several antenna insulators
must have been about 1800 megohms. A not unreasonable figure.

It's surprising what can be deduced from a simple but fundamental
relationship such as -

Q = C * V = I * T

where Q = capacitor charge in Coulombs, C = Farads, V = volts, I =
amps, T = seconds.

It's only arithmetic. ;o)

You could now estimate the receiver noise level in dBm, due to
precipitation of rain drops of given average diameter, on an antenna
at a rate of N drops per second, each drop charged up to a potential
of V volts relative to ground. You would, of course, have to take
receiver bandwidth and a lot of other things into account. So it's
probably not worth the time and trouble.
----
Reg.

Cecil Moore wrote:
Tom Donaly wrote:

Cecil, if you're too chicken to do the experiment, just say so,
I'll understand.


I did the experiment and posted how to do it.
Here it is again: Bring one end of a dipole down close
to the system ground rod. Charge up a capacitor to 12v.
Discharge the cap between the end of the dipole and
the ground rod. That pop you hear is NOT corona.

Most raindrops don't have a little plate and a wire to ground.
In order to mimic a raindrop, Cecil, you'd have to leave the
ground terminal of your capacitor floating. Do that and tell me
what you hear. Anyway, you're still not addressing the real
issue: can you tell whether or not it's raining solely by
listening to the static noise on your antenna?
73,
Tom Donaly, KA6RUH