In message , Szczepan Bialek
writes
"Richard Clark" wrote
.. .
On Fri, 16 Oct 2009 12:27:02 -0700 (PDT), wrote:
I think the height of the object relative to it's surroundings, and
it's ability to stream mean more than anything.
Hi Mark,
There's another angle to be observed here. Globally, there is a
potential difference between earth and sky that runs to several
hundred volts per meter,
The Earth has the excess of electrons. The Earth produce the electric field
about one hundred volts per meter. In a suuny day the electrons migrate up
with the heavy ions (aggregates of H2O molecukes).
with a current flow on the order of
femtoAmperes per square cM. Not much locally, but for the full
surface area of earth it is the electron conveyor belt charging the
clouds through dust migration.
This "electron conveyor belt" charge the air. Next the air becomes cooler
and the condensation take place. Clouds appear. The condensation cause the
voltage rise. All types of sparks jump.
Under clouds the electric field has the opposite direction and thousands
volts per meter.
At this potential and current, absolutely everything is a short
circuit that penetrates the voltage isoclines raising earth towards
the clouds.
The high voltagi in the clouds is lowered by the "electron conveyor belt"
and the lightning.
The "electron conveyor belt" is more effective if the Earth have many sharp
needle.
So there are the two possibilities:
1. If "The intention is to PREVENT a direct lightning strike," - many sharp
needle is used,
2. If the intention is to CATCH a direct lightning strike and conduct a
strike to ground - a polished big ball is used.
S*
In the early days of lightning conductors, I believe that the French
didn't like the nasty pointy things which the British had installed.
Instead, they decorated theirs with fancy balls at the top - with
sometimes disastrous results.
--
Ian