My belief is that, the the capacitance we're compensating for by tuning
slightly lower, is actually the ion cloud that surrounds the discharge
terminal *before* breakout. When the potential of the "charge-cloud" (
or what, I think, Richard Hull called the "isotropic capacitance")
overrides the ability of the air to insulate, we get discharge.
Basically, the charged air around the discharge terminal effectively
increases the "size" of the terminal, thus lowering the operating
frequency. In my opinion, it's not the streamers that do the majority of
terminal-loading.
Dan K.