Unfortunately that doesn't match up with well know and published information
about lightning. The development of the stepped leader has been tracked
using vhf triangulation techniques to generate 3d pictures of how the leader
starts in the cloud and progresses down to the ground in a series of 50-100m
steps. Take a look at the techniques and results of this experiment:
http://ibis.nmt.edu/nmt_lms/steps_2000/ This process progresses much more
slowly than would be caused by a cosmic ray event and 'runaway breakdown'.
A 'runaway breakdown' is what happens in a spark, something much different
than the development of a lightning bolt. This site has a decent
description of the widely accepted explanations:
http://www.ghcc.msfc.nasa.gov/lisotd_old.html. The biggest problem with the
'runaway breakdown' theory is the speed of development of the stepped
leader. This leader can develop over the period of several seconds to maybe
a minute in a kind of random walk effect. If it were triggered by a single
cosmic ray it would have to be much quicker as the narrow ion trail left by
a cosmic ray would dissipate too rapidly for the large amount of charge that
is transferred in a typical stroke to follow. You can also study the
waveforms and induced fields from strokes to determine the charge density in
the stepped leader when the stroke is triggered, again, there is much more
charge in the leader then could be accounted for by a cosmic ray channel.
and that charge accumulated in that channel very slowly because it does not
cause large magnetic fields while it is accumulating, only when the final
discharge occurs. Triggering by a cosmic ray would also not allow for some
of the stroke attraction effects seen from power lines and large towers and
buildings, the distribution of strokes would be more random and not show the
well documented attraction to large conductive objects. The normally
observed discharge rate of strokes would also not support this theory. A
long thin ionized channel that would be created by a cosmic ray would have a
very high resistance and would be discharging a charged region in the cloud
to a charged region on the ground through that channel, this would require
the current to start small and build as it added energy to the channel. The
observed effect is just the opposite, the discharge starts out fast, rising
to max current in 1-2 microseconds and then tapering off as the highly
charged stepped leader discharges. follow on strokes then use this rather
fat channel to discharge other pockets of charge down the same path. Too
many inconsistencies for me, and no new predictions, neither of which lends
much to support their new theory.
The theorists who are trying to promote that runaway breakdown theory have
latched onto the detection of x-ray emissions as an phenomena that was not
explained by the old theories. However, that is an after effect of a stroke
and the last I saw may be related to sprites and jets that are discharges
from the top side of the cloud up into the ionosphere. These are generally
believed to be due to the large charge imbalance in a cloud after a large
discharge between the cloud and ground. When this happens it leaves a large
charged area in the very far upper reaches of the cloud that is no longer
bound to the opposite charge at the bottom of the cloud, it is natural for
it to try to discharge in the opposite direction. and since the field is
very large and the atmosphere much thinner at the highest part of the cloud
it is possible to get relativistic speeds out of electrons. This is one of
the mechanisms proposed for the observed speeds of blue jets. Check out
some of the info at: http://elf.gi.alaska.edu/ on those phenomena. I'm not
sure if that is the site that goes into the relativistic effects or not, but
there are others on the web.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
-----Original Message-----
From: W0UN -- John Brosnahan [mailto:shr@swtexas.net]
Sent: Saturday, February 11, 2006 19:36
To: k1ttt@arrl.net; reflector -tower; Keith Dutson
Subject: Re: [TowerTalk] lightning and insulated elements..
At 12:32 PM 2/11/2006, David Robbins K1TTT wrote:
You are mixing up a couple things... 'cosmic rays from a strike' has nothing
to do with how strokes occur. There is some evidence for very large strokes
causing enough of a field to cause x-rays and maybe higher energy particles,
but that is after the fact.
The causing of strokes by cosmic rays is another thing all together. Even
with assistance from cosmic rays there is not enough potential to bridge the
gap from cloud to earth in one step. And if cosmic rays really did cause
enough of an ion trail all the way from the cloud to the ground then the
strokes would always be arrow straight, which obviously they aren't. the
phenomena of leader progression and streamers is very well documented now
and explains very nicely how the stroke channel grows in steps from the
cloud or ground and how the final connection is made to start the discharge.
This also works for strokes that progress a very long distance away from the
cloud, no need for cosmic help in either case.
-----
There is a new trail of research suggesting that cosmic rays help to trigger
the breakdown. Here is a note from wikipedia.org and a reference to a
recent paper.
Cosmic rays have been implicated in the triggering of electrical breakdown
in lightning. It has been proposed [see Gurevich and Zybin, Physics Today,
May 2005, "Runaway Breakdown and the Mysteries of Lightning"] that
essentially all lightning is triggered through a relativistic process,
"runaway breakdown", seeded by cosmic ray secondaries. Subsequent
development of the lightning discharge then occurs through "conventional
breakdown" mechanisms.
The reference for Keith is NOVA ScienceNOW and it aired OCT 18, 2005.
John W0UN
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