kinds of spark

["Richard Barton" <richardbarton-at-caving5.freeserve.co.uk> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

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.