Noise level between two ant types
 

On Fri, 16 Jun 2006 18:03:45 GMT, "Tom Donaly"
wrote:

Cecil Moore wrote:

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.

Nevertheless, air is in a constant state of conduction. It may
only be picoamps per square meter but it still exists and it's
what causes the earth to be a lousy capacitor.

Hi Tom,

To support your statement with more specific characteristics, from a
1972 copy of "Astronautics and Aeronautics:"

That capacitor can be described as roughly 3.54 F to the
atmosphere at an elevation of 50km;

charged with a world-wide continuous 630 MW flow;

with a potential difference (average) of 350 KV;

and current (average) of 1800 A.

Taking this current, from earth, on a basis of cm², the current is
then 90 aA about 1 pA/m² as you said the same article goes as high as
2.5 pA/m². The difference is I used an homogenous earth model, the
author uses a real model with oceans and land with seasonal
variations.

"...the equipotential planes remain remarkably
horizontal in spite of winds, thermals, drizzle,
and cloud cover."

"few persons realize that when a person stands
in an open field on a clear day, his head has a
potential approximately 300V more positive than his feet
and .... The gradient averages about 180 V/m over land
in the summertime."

"The gradient in the austauch or mixing layer varies more
than at high altitudes because thermal convection
in this region often lifts ions and particles from such
sources as pollution, dust, and fog, thus generating an electrical
convection current."

This "austauch" layer, by observation of accompanying charts, appears
to be the first mile (actually 7000 feet) in elevation where
conductivity is flat at 200 micro-esu;
the electric field starts at 180 - 200 V/m,
to then vary downward to 60 V/m;
and Charges/cm³ goes from 0 to -2 in the first 2000 feet,
and rises to +18.

The "austauch" layer may, in fact, be this first 2000 feet where the
charge density is negative. This accounts for the heavier positive
ion drift downward compared to the lighter negative ion rise into the
atmosphere. Be that as it may, the description is suitable for
antennas and high places.

73's
Richard Clark, KB7QHC

Noise level between two ant types
 

Cecil Moore wrote:
Gene Fuller wrote:
If every interaction between objects requires that somehow the charge
is transferred to keep things "identical", how did those nasty dust
particles get charged in the first place?

Huh? It is you who says the dust particles carry exactly the
same charge as the antenna they are encountering. Otherwise,
there is current flow in the antenna system which you deny.

I am not arguing about antenna noise. I am questioning your misuse of
physics. There are no charge equalization laws.

Huh? Place a charge on a wire. Doesn't current flow in
both directions until the charge is equalized throughout
the conductor? Did my college professors lie to me?

Cecil,

If your college professors actually said that, then yes, they lied.

Try looking in any basic physics text. I believe you will find
discussion of electrostatic forces, equipotential surfaces, fields, and
Gauss' law. It is doubtful that you will find any technical description
of charge equalization.

Simply grabbing random techno-factoids and assembling them into some
sort of support for your case does not really help.


(I said nothing about dust particles. I merely asked you how they got
charged.)

73,
Gene
W4SZ

Noise level between two ant types
 

Gene Fuller wrote:
Cecil Moore wrote:

Gene Fuller wrote:

If every interaction between objects requires that somehow the charge
is transferred to keep things "identical", how did those nasty dust
particles get charged in the first place?


Huh? It is you who says the dust particles carry exactly the
same charge as the antenna they are encountering. Otherwise,
there is current flow in the antenna system which you deny.

I am not arguing about antenna noise. I am questioning your misuse of
physics. There are no charge equalization laws.


Huh? Place a charge on a wire. Doesn't current flow in
both directions until the charge is equalized throughout
the conductor? Did my college professors lie to me?


Cecil,

If your college professors actually said that, then yes, they lied.

Try looking in any basic physics text. I believe you will find
discussion of electrostatic forces, equipotential surfaces, fields, and
Gauss' law. It is doubtful that you will find any technical description
of charge equalization.

Simply grabbing random techno-factoids and assembling them into some
sort of support for your case does not really help.


(I said nothing about dust particles. I merely asked you how they got
charged.)

73,
Gene
W4SZ

It isn't the charge that is equal, it's the potential. If there were
a potential difference between two places on a conductor, there would
be a current and then the conditions wouldn't be static. David K. Cheng
addresses this in his book _Field and Wave Electromagnetics_. I think
it's Cecil's memory that lied to him rather than his professors.
73,
Tom Donaly, KA6RUH

Noise level between two ant types
 

Richard Clark wrote:

On Fri, 16 Jun 2006 18:03:45 GMT, "Tom Donaly"
wrote:


Cecil Moore wrote:


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.

Nevertheless, air is in a constant state of conduction. It may
only be picoamps per square meter but it still exists and it's
what causes the earth to be a lousy capacitor.


Hi Tom,

To support your statement with more specific characteristics, from a
1972 copy of "Astronautics and Aeronautics:"

That capacitor can be described as roughly 3.54 F to the
atmosphere at an elevation of 50km;

charged with a world-wide continuous 630 MW flow;

with a potential difference (average) of 350 KV;

and current (average) of 1800 A.

Taking this current, from earth, on a basis of cm², the current is
then 90 aA about 1 pA/m² as you said the same article goes as high as
2.5 pA/m². The difference is I used an homogenous earth model, the
author uses a real model with oceans and land with seasonal
variations.

"...the equipotential planes remain remarkably
horizontal in spite of winds, thermals, drizzle,
and cloud cover."

"few persons realize that when a person stands
in an open field on a clear day, his head has a
potential approximately 300V more positive than his feet
and .... The gradient averages about 180 V/m over land
in the summertime."

"The gradient in the austauch or mixing layer varies more
than at high altitudes because thermal convection
in this region often lifts ions and particles from such
sources as pollution, dust, and fog, thus generating an electrical
convection current."

This "austauch" layer, by observation of accompanying charts, appears
to be the first mile (actually 7000 feet) in elevation where
conductivity is flat at 200 micro-esu;
the electric field starts at 180 - 200 V/m,
to then vary downward to 60 V/m;
and Charges/cm³ goes from 0 to -2 in the first 2000 feet,
and rises to +18.

The "austauch" layer may, in fact, be this first 2000 feet where the
charge density is negative. This accounts for the heavier positive
ion drift downward compared to the lighter negative ion rise into the
atmosphere. Be that as it may, the description is suitable for
antennas and high places.

73's
Richard Clark, KB7QHC

Hi Richard,
that's pretty much the basis of my interpretation of
Tom Rauch's experience with precipitation static. Some authors
(Feynman for one)claim the earthly capacitor is constantly being
recharged from lightning storms in the tropics. I don't understand
dust storm electrodynamics, though, but since Saint Elmo's fire has
been seen in dust storms it may still have something to do with
the earth's electrical field added to whatever produces the
potentials within the dust storm.
73,
Tom Donaly, KA6RUH

Noise level between two ant types
 

There ya go. REAL data.

Noise level between two ant types
 

Thanks Richard and Tom D.

I was worried for a while mythology and the magic dust (not Cheech and
Chong style, but Texas style) would overshadow what really goes on.

Richard Clark wrote:
"few persons realize that when a person stands
in an open field on a clear day, his head has a
potential approximately 300V more positive than his feet
and .... The gradient averages about 180 V/m over land
in the summertime."

We have to be careful with that!

Actually the impedance of the field is very high. When a person stands
in an open field he actually perturbs the electric field very close to
him because his body resistance is very very low compared to the
impedance of the electric field. His feet are not really 300V more
negative than his head unless you would replace everything below his
eyebrows and above his ankles with a very good insulator.

On calm windless days the electric field in the air around a structure
like an antenna is easily bled off even through extremely high values
of resistance, and when the wind picks up, especially when there are
particles of some type, the electric field impedance is effectively
reduced.

There are some people who believe in magic. Some people think a tall
metal structure has a potential difference between ends that builds up
in storms, eventually charging the top of the structure so much it arcs
to the clouds above.

To cure that pure fantasy they put little spikey balls on the top of
their tower, somehow thinking the leakage from that corona that Cecil
knows doesn't exist bleeds off the charge and makes the clouds above
and earth below the same potential.

It's very strange how those people all argue with each other and argue
against themselves, but then that's what happens when too much magic
dust hits an antenna.

73 Tom

Noise level between two ant types
 

wrote:
To cure that pure fantasy they put little spikey balls on the top of
their tower, somehow thinking the leakage from that corona that Cecil
knows doesn't exist bleeds off the charge and makes the clouds above
and earth below the same potential.

Please stop fibbing about what I said. As far as I know,
virtually all the localized static problems I have here
in East Texas is corona. I am not aware of any charged
particle problems in my high humidity environment.

But I experienced something different in the Arizona
desert that cannot be explained by corona.
--
73, Cecil http://www.qsl.net/w5dxp

Noise level between two ant types
 

Gene Fuller wrote:
Cecil Moore wrote:
Try looking in any basic physics text. I believe you will find
discussion of electrostatic forces, equipotential surfaces, fields, and
Gauss' law. It is doubtful that you will find any technical description
of charge equalization.

On the contrary, my DC circuits book has an example of the
charges on two identical capacitors equalizing when they
are paralleled.
--
73, Cecil http://www.qsl.net/w5dxp

Noise level between two ant types
 

Noise level between two ant types
 

On 16 Jun 2006 19:18:44 -0700, wrote:

Thanks Richard and Tom D.

I was worried for a while mythology and the magic dust (not Cheech and
Chong style, but Texas style) would overshadow what really goes on.

Richard Clark wrote:
"few persons realize that when a person stands
in an open field on a clear day, his head has a
potential approximately 300V more positive than his feet
and .... The gradient averages about 180 V/m over land
in the summertime."

We have to be careful with that!

Actually the impedance of the field is very high. When a person stands
in an open field he actually perturbs the electric field very close to
him because his body resistance is very very low compared to the
impedance of the electric field. His feet are not really 300V more
negative than his head unless you would replace everything below his
eyebrows and above his ankles with a very good insulator.

Hi Tom,

Quite true. Its as if a needle has penetrated the equipotential
shells over that 300V span. Streamlines would probably reveal a dead
short to what are in the distance 300V/90aA = 3,333,333 GOhm resistive
paths.

The author's intent was to design a plane's auto leveling (in flight)
mechanism by sensing the voltage differential while banking. He
accomplished this by placing sensors at each wing tip turning the span
into a bridge circuit. He wasn't sensing voltage, but instead using
current. The plane would be already shorting out the potential, so he
had to turn this lemon into lemonade.

The problem was that the sensors had to grab hold of the current
before the massive short hogged it. The solution was to use mildly
radioactive isotopes to "make good electrical contact with samples of
air at two different points in the vertical potential gradient...."
Those radioactive sources were 500 µCurie Polonium Alpha emitters -
the kind I used to remove static from records back in the early 70s
(your solution to taking care of paper static, Tom D.).

73's
Richard Clark, KB7QHC