Now admittedly it's hard to say what you're looking at, but I find it interesting that this is essentially a lightning bolt striking the bottom of the glass sky (or am I wrong about that?), and that it would take those conical shapes... I just wonder if perhaps it is taking the "path of least resistance" around the completely transparent, hanging ice, sort of an upside-down mountain.
Thoughts? Even if not, this stuff is obviously happening right at the level of the glass sky, and the perfectly flat dissipation patterns are quite interesting.