I received a personal message about the discussion (here) on lightning, that got got me thinking about the vagaries in the different types of lightning.... like my account of that errant bolt that decided to take out a piece of the equipment hut rather than follow the ground strap that countless other hits had coursed. Why did it do that?.. to be more precise, what exactly made it decide to do that?
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Okay, the physics can give some insight- and a technical warning too- to a lightning bolt. They are comprised of some incredibly high radio frequency pulses- and behave according to the same rules employed in RF circuits. In the case of "Cinderblock," we figured the length of the copper strap and its slight drip-loop at its ground tie point formed an efficient RF choke that sent the errant bolt off thru the wall. That's cool- the drip loop is now gone- impedence should have dropped---- let's see if Zesus notices.
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This recalled to me a project of my friend and work Sidekick, "Barbi." **
She was running a HIPAS (High Power Auroral Stimulation) project using a former military site, far far above the Arctic Circle. The site had been moth-balled for some time and it was with no considerable effort we got things reasonably back in order. The heart of this installation- or at least the part we were interested in, was the high power'd Blow Torch of a HF transmitter and its curtain array antenna.
When the transmitter was brought back to life, at a greatly reduced power output, that antenna was not taking the load correctly. All the parameters were off, and it would have been a disaster to continue the project at high power until it was corrected. The most likely cause, consensus had it, was a corroded/weather'd connection(s) somewhere in that antenna array. But where?
Barbi came up up with a novel diagnotic.. at night, the transmitter on, we'd look for arc's at the myriad bolt'd joints in the array.
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But... it was like looking for needles in a hay stack ..................... (hang in there, the lightning part is coming up....
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Then another bright idea. Modulate the signal and Listen for the arc's. So we readjusted the bias on the PA from a Class C to AB1, and feed Barbi's stream of a Blondie CD into the driver as AM. We figured that a few hours of Debbie Harry was better than a warbling tone or some such.. we don't ID, and never think of asking for SWL reports.
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Next night- the setting. It was like 50 below- crystal clear sky- the Aurora streaming from horizon to horizon.....
"the Northern Lights were running wild in that Land of the Midnight Sun...." (..........Robert Service.) And so was the transmitter.
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And outside you could here music!
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Barbi, in her parka, boots and gloves- went out to locate the arc's. She was gone but a few minutes when she came bursting back into the building:
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"Lauri !, Guys!... come quick, you won't believe this !.... C'est un feu d'ange !"
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(she's French...this happens often when excited ) ...
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"Angel Fire?.. what are you talking about?"
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"Come out side. Quickly, Run!!.......Ahh, its Ball Lightning! ... its dancing on the curtain !"
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By the time we made it out the door into that bitter cold (I wasn't wearing a coat or gloves)-- it was gone. But Debbie was still singing in the wires.
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"It was right there!" said Barbi, pointing to the array,
"It was about 2 feet in diameter, a bright blue ball of light!... it float'd to the ground over there.." (pointing to a tower base.)
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"And that's when I came and got you"
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Well. there was nothing to see and I was rapidly freezing. Coyote Frostbyte for real.
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Back inside, a little skepticism was in the air.. not on my part, mind you (smiling).. but I couldn't help but ask my friend:
"Where is the bottle of Vodka?.... this wasn't...... Oh, never mind"
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But the next morning, at the base of the tower was a hole melted thru the snow down to the earth- a perfect 2 foot diameter circle.
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If a French physicist says she sees Angel Fire- believe her.
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Was it Ball Lightning?,, where did it come from? There aren't storms like that there in the dead of winter.....
I have seen St. Elmo's fire several times, but never Ball Lightning............. Maybe I really don't want to!-- but have any of you had such and experience, ever seen
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................ un feu d'ange ?
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...................................................CF
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Story told while sitting in an airport- this connecting flight lay-over stuff is time best turn'd to stories...
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**Her nickname, I'll leave it to the imagination why- its her work radio callsign too- Barbi is a PhD., particle physicist.
