In #268 above, I should have said “underside of its contrail.” If the contrail is horizontal, there is no “bottom,” just the underside. The plume is vertical and actually HAS a bottom, but no underside until it starts to arc north-west; the plume’s bottom is lit just like its top — from the west, so the vast majority of reflection is — as it is on the entire plume — reflection on the west side — that is, the side we cannot see because we, too, are looking west. It’s why the length of the plume is mostly in shadow — the side we’re seeing is facing east. Not downward toward the sea, but east.
Rush Limbaugh reported today (11/23), it was a MISSLE!