My understanding follows somewhat as Scott put it, as follows.
In a storm, clouds rotate much like a generator producing AC, and a state of strain exists between the top + and bottom -of the cloud formation (capcitor effect).With AC, the + end is short of electrons, so when the dielectric breaks down, the + end gets its supply from the - end, the strain is relieved and a flash results.
In other situations, a state of strain also exists between the clouds and the ground, which has an even greater supply of electrons, and when this strain breaks down, a strike results - logically from the ground up. We see the strike moving downward, but I believe this is due to the illumination of the ionised air - not the strike itself.
I take the point re the small strap of copper lightning conductors - and Ben Franklin's sterling work, which I assume took place during a quiet phase in the affairs of state - but they seem to work satisfactorily - and it is interesting to note that other skyscrapers in the area may not need to bother with lightning conductors as they can rely on the Empire State attracting any wayward strikes!
Hope this helps.
Ron Braggins - England
