10cs; 2I have. Nobody knows what causes it. I presume you do, TTT, me old china? I don't need to look it up anyway, TTT. You know everything don't you, so delete Google Answers. TTT knows it all! " - the cause is well known and explained, just google and you will find in many places:
"... which occur when lightning discharge in a thundercloud temporarily changes the electric field above it. This adjusts the orientation of the ice crystals so that they refract the sunlight differently, making the sundogs move around as if they're jumping."