Re: kinds of spark

["Malcolm Watts" <M.J.Watts-at-massey.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi Richard,

On 26 Jul 00, at 12:29, Tesla list wrote:

> Original poster: "Richard Barton" <richardbarton-at-caving5.freeserve.co.uk> 
> 
> Hi all
> 	From my secondary top ball, I normally get (into free air,
> NOT onto a grounded probe), the usual random mass of seething
> sparks, in all direrctions and bluish-white, but every 20 seconds or
> so, this wild mass of sparks is replaced by a single, very bright white
> spark, which is about the same length, but noisy, and which tends to
> fire vertically, or nearly so, and wanders around. This spark will last
> for perhaps 3 to 5 seconds before giving way to the normal discharge.
> Can anyone explain why this happens, and is it indicative of near-
> perfect resonance. There seems to be a lot of power in this "special"
> spark.
> 					Richard Barton.

That is a characteristic of a spherical topload. Convection 
keeps the spark almost vertical. I think turbulence and 
vortices formed as the airflow increases eventually causes the 
spark to collapse although I've seen one hanging there for the 
best part of thirty seconds. 

Regards,
Malcolm