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Re: very long sparks

Bert, Stan

You might also note in your analysis the average forking in a lightning
discharge is 16 degrees.  This also applies to other forms of high voltage
discharges as well.

Dr. Resonance


-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Monday, January 10, 2000 7:06 PM
Subject: Re: very long sparks


>Original Poster: Bert Hickman <bert.hickman-at-aquila-dot-com>
>
>Stan and all,
>
>I didn't do any smoothing, so there may be some dots or interaction
>between the dots and pixels from the scanning process.
>
>You've done an excellent job of disecting and analyzing the picture!
>Since the source is some type of impulse generator, there's probably no
>heat-rise effect, since the discharge would be more like a single
>lightning bolt, and it does exhibit the sinuous pattern typical of a
>lightning-like discharge.
>
>The big ball of light at the far tower might be a flashover from one of
>the lines to the tower. This often happens during strikes to
>transmission lines. It can also happen during a strike to the top ground
>wire if the grounding system is insufficient to handle the lightning
>surge, and the tower potential rises to the point where insulator
>strings flahover between the lines and the tower. For a spectacular
>picture of this happening on a 115 kV transmission line, check out:
>http://www.pti-us-dot-com/pti/consult/dist/gallery/champ/thehit.htm
>
>I think the shot represents a very real event...
>
>-- Bert --
>
>Tesla List wrote:
>>
>> Original Poster: Stan <sdarling-at-columbus.rr-dot-com>
>>
>> Bert: Did you use descreening on your scanner when you scanned this
>> photo in?  I notice some print screening in the photo....
>>
>> For what I talk about below refer to:
>>
>> http://users.better-dot-org/sdarling/longspark/longarc.gif - I drew on the
>> original image in red and black
>> http://users.better-dot-org/sdarling/longspark/longarc_inverted.gif - same
>> image, just inverted to show detail
>>
>> I agree that when I first looked at the photo I sort of scratched my
>> head.  I agree the discharge path seems awfully circuitous.  Perhaps if
>> the arc duration were long enough there could have been a rising
>> heat/jacob's ladder effect?  Its general shape looks like the arc you
>> get from a NST HV terminal to ground.
>> If you look closely, it appears there might be a short rod sticking off
>> the top of the tower.  Notice how the first fraction of the spark is
>> very straight and much thinner than the rest?
>>
>> Also, what the HECK is that big ball of light at the top of the left
>> power line tower?  It seems too bright to be ordinary glare or
>> relfection.
>>
>> As for the shadows--yes they do seem odd.  I think it might be a daytime
>> shot taken with infrared film.  The shot is taken from a building and
>> the sun is behind the building.  I think the sky being black (a classic
>> signature of infrared film) tricks your eyes into thinking it's night,
>> thus making the shadowing appear very weird.  The strangest thing I see
>> re shadowing is abotu 2/5 of the way from right side of the picture.
>> Notice the three parallel slightly curved lines/shadows going at about
>> 135 degress (to the back left of the picture)?  It seems these could be
>> shadows from the power lines.  Of course, this shoots down the sun
>> behind a building theory unless there are very bright artificial light
>> sources.
>>
>> As for determining scale, the best indicator I see is at the bottom
>> right of the transmitting tower. There appears to be a one-story
>> entrance/lobby to the base of the round tower.  If one figures it would
>> be about 12 feet tall, then one can estimate the height of the tower
>> fairly accurately.  I show about 8.5 x or 8.5 x 12 feet or almost
>> exactly 100 ft.  The straight line distance from the spark start on the
>> tower to where the spark goes off the photo is 2x the tower height, or
>> about 200 ft.  Assuming the spark really did hit the power lines, and
>> extending the fence off the edge of the photo, and assuming the lines
>> run parallel to it, there is about 50 ft of spark not caught in the
>> photo.  So total estimated spark length is about 250ft.  Of course this
>> is assuming the spark is at a 90deg angle.  If it's more or less than
>> that, the spark length is higher.
>>
>> Comments welcome.
>>
>> -Stan
>>
><SNIP>
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