Re: Natural streamer :)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Scot and all,

Wow and congratulations - you truly had a once-in-a-lifetime experience!
Upward directed leaders form when the local e-field from a downward
moving negatively charged lightning leader gets strong enough to
initiate smaller positively charged leaders from the tops of grounded
objects below. When the upward leader connects with the downward one it
initiates the main, high current return stroke. This usually happens
quite quickly - typically only a small fraction of a second before the
main return stroke. The fact that yours took 2 seconds to form is really
awesome! 

Mini-leaders also form on grounded objects as the leaders and streamers
from Tesla Coils propagate towards them. While often mistaken for
corona, longer (1" or longer) arrested leaders can also form. Try the
following experiment in a dark room:

Provide a grounded object having a small radius, and locate it just
beyond your coil's maximum strike length. Use a breakout bump on the
toroid to direct leaders towards your grounded object. When running the
coil, you should see short (1-2") mini-leaders leaving the grounded
electrode, heading towards the leaders coming from the HV terminal. If
the two leaders actually connect, you'll see a thin blue spark that
completely bridges the gap. 

If set up correctly, you'll also see the blue "haze" of countless
streamers (the cold discharges that are ahead of the hotter (brighter)
leaders) in the gap between the tips of the leaders. A good picture of
arrested leaders (those that don't bridge the gap), streamer haze, and
mini-leaders at the grounded terminal can be seen here (from Sue Gaeta):
http://community.webshots-dot-com/photo/1865657/14639311EqIXoLWpyc

If you get any better pictures that show these phenomena, please share
them with us!

Best regards,

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
"Electromagically" Shrunken Coins!
http://www.teslamania-dot-com 

Tesla list wrote:
> 
> Original poster: "BunnyKiller by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<bigfoo39-at-telocity-dot-com>
> 
> Hi All...
> 
> Just saw one of the most really cool things about 15 min ago..   (
> 10:17am 07-14-02)
> 
> I was going to go pick the wife up from work and while I was sitting at
> the stop lite, I looked over to my left and saw a streamer growing off
> the top of a metal lamp post frame. It started about 1' in length and
> increased to about 9' in about 2 seconds. and you guessed it ....
>  lightning struck ...   blew the cap off of the pole and all the lights
> down the street went out. Darn near hurt myself trying to jump away from
> the window while in the car...   ( kinda funny now that you think of it )
> 
> Always heard about the pre strike streamers forming before a strong
> strike but thought Id never see one...
> 
> kinda makes me wonder if mini streamers form on the grounded object our
> coils go for....
> 
> Scot D