Screwy Twisty

An unusual instance of contrail twisting -- not only does this one twist on itself, it actually winds around an axis exterior to itself, like a winding staircase.  Minor examples of this epiphenomenon have been seen before, but this one is the clearest, best illustration I have seen so far.

Or maybe it's the trail of one of those Asiatic dragons of Southern California descending to earth..? (for explanation see:  Dracovolans australocaliforniensis maximus)