The problems encountered in measurement of lightning strikes is similar to
those associated with weather prediction. You know a storm is brewing but
the data needed to predict where, when and how much is just too overwhelming
to be absolutely accurate. Streamers can happen just about anywhere,
regardless of the method used to direct them to one location or the other.
However, in general you can say the streamers are the path of least
resistance (impedance) from positive and negative sources. In the case of a
strike from cloud to earth, I believe the leading streamer is actually a
group of small streamers spread out over a large area. Thus, a single
strike can hit tree, power and phone lines simultaneously with various
amounts of current to each.
Keith
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of doc
Sent: Friday, March 18, 2005 11:32 AM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] lightning & trees
Im my mind the laws of physics are predictable else they are not laws. I
believe that the physical universe is balanced and orderly, even if there
remain many facets we have yet to comprehend due to the complexities of
inter-related variables.
While the variables may be multiple and difficult to identify and to predict
they are nonetheless available to identification and predictability.
My questions go to whether scientists yet understand them or if this is one
of the areas where they are still learning.
It would logically follow that knowing the how of streamers would provide
the building blocks upon which mitigation techniques may be developed.
Postulating that lightning and related elements (e.g. streamers) are
unknowable (and/or random) sounds more like mysticism than science and that
is what has been making me uncomfortable.
;-) doc
Kelly Taylor wrote:
> Hi Doc,
>
> I'm no expert, but it seems to me that charges build up where they do,
> be it near a tree or some other structure or not.
>
> As soon as it reaches arc potential, it's going to arc. And because of
> variations in the path, that can happen sooner or it can happen later.
>
> Consider an HF amp with arcing problems. The loading capacitor has
> flat plates that are always the same distance from their neighbour
> when meshed or partially meshed. Why does an arc choose one spot to
> arc over one time and a different spot the next?
>
> And, why does it arc at 3 kv potential one time and 2.5kv the next?
>
> 73, kelly
> vext
> ----- Original Message -----
> From: "doc" <kd4e@verizon.net>
> To: <towertalk@contesting.com>
> Sent: Thursday, March 17, 2005 9:59 PM
> Subject: Re: [TowerTalk] lightning & trees
>
>
>
>>Earlier today I was showing our college math teacher the "Physics for
>>Criminal Justice Majors" course materials from 1974 when I attended
>>Northeastern University.
>>
>>As we thumbed through the mimeographed pages (no textbook existed at
>>the time) I observed that I had no idea what the formulas meant, even
>>though some were written in my handwriting on the note pages!
>>
>>Although I passed the course I remain a physics-challenged Ham.
>>
>>That said, I think I may have a better sense of the issues now.
>>
>>The multiple-variable point is well-taken such that the best path is a
>>moving target.
>>
>>As for the resistance/potential issue I was speculating as to best
>>path without intending to isolate resistance as a decisive factor --
>>wondering aloud just what it is that at any moment makes one object
>>versus others more prone to send out streamers and thus become at
>>least momentarily more attractive.
>>
>>It is reasonable to postulate that conductivity-of-the-moment causes
>>energy to move through an particular object (or assorted elements in
>>conductive moisture in the air) more so than another?
>>
>>doc
>>
>>
>>>It seems to me the answer lies in the unpredictability of the "best
>
> path."
>
>>>You have to look at that equation in four dimensions: co-ordinate
>
> geometry
>
>>>set against time.
>>>
>>>Variations in humidity and wind currents mean that at any given
>>>second,
>
> the
>
>>>"best path" may not be what it appears to be ** at that moment **.
>>>
>>>As well, if a charge builds up 10 feet from a tree, adding the ground
>>>resistance to the tree's resistance may mean that moving through the
>
> ground
>
>>>to the tree and into the air isn't the path of least resistance, just
>
> going
>
>>>straight into the air may be.
>>>
>>
>> > I'd like to know some physical reason why a change in resistance
>>would > make the cloud to tree potential change. That's what doesn't
>>make
>> > sense to me.
>>
>>
>>--
>>Thanks! & 73, doc kd4e
>>
>> |_|___|_|
>> | | & | |
>> {|
>> /\ {|
>> / \ {|
>> / \ {|
>> / @ \ {|
>> | |~_|~~~~|
>> | -| | |
>>============\ # West Central Florida
>> KD4E ==============================
>>http://bibleseven.com/steelhouse1.html
>>Ham PC = 100% Linux Novell-Suse 9.2
>>Halli, Heathkit, Homebrew, MFJ, TenTec, Yaesu Radio Life:
>>http://www.gospelcom.net/twr/ Linux-Incompatible hardware is
>>defective!
>>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>_______________________________________________
>>
>>See: http://www.mscomputer.com for "Self Supporting Towers",
>>"Wireless
>
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041
> with any questions and ask for Sherman, W2FLA.
>
>>_______________________________________________
>>TowerTalk mailing list
>>TowerTalk@contesting.com
>>http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
--
Thanks! & 73, doc kd4e
|_|___|_|
| | & | |
{|
/\ {|
/ \ {|
/ \ {|
/ @ \ {|
| |~_|~~~~|
| -| | |
============\ # West Central Florida
KD4E ==============================
http://bibleseven.com/steelhouse1.html
Ham PC = 100% Linux Novell-Suse 9.2
Halli, Heathkit, Homebrew, MFJ, TenTec, Yaesu Radio Life:
http://www.gospelcom.net/twr/ Linux-Incompatible hardware is defective!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
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