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