Hi Terry,
> So the streamers ionize the air and add a dynamic boundary condition
> to the electrostatics between the topload and antenna.... I cannot
> immediately confirm or deny that...
Well, luckly we don't need to do that. In 1986, in France, Les Renardieres
group did that measurement and documented it thoroughly in a publication.
See:
Les Renardieres Group: Double impulse tests of long airgaps. IEE Proc. A,
pp. 3-483, vol. 133, Pt. A, no. 7, 1986.
After them, a sequel of papers from many authors have confirmed their
findings. Nowadays it is an assumed fact, not an hypothesis.