How a plasma wire is constructed and how lightning currents
flow are two completely different events - happen at different
times during a CG lightning event. How a streamer is built
has nothing to do with the OPs original question. Lightning,
as his question asks, is not going one direction. Lightning
is a powerful RF wave. IOW it goes both directions. BTW
powerful but typically not that much energy at a strike
location.

Jim Hampton wrote:
I believe I've read that "streamers" go up and there are a number of quick
strikes before the big show. Best bet is do a google search on lightning
and see what turns up. I haven't ever worked with the stuff (thank
heavens!) Of course, if anyone is in the way of it - does it matter if
it goes up or down? BTW there was an article in the newspaper in the last
week or so - some guy finally came home from extensive rehabilitation. He
still is far from normal. He was a boy scout and a tree was hit near where
he was standing. This occurred in the late 1990s and he just came home
within the last two weeks!