Most theories about the formation of Clear Air Turbulence relate to eddies along the edges of high altitude jet streams. Why some jet streams have sharply defined edges may not yet be clearly understood. This begs the question as to how the jet streams form intead of the air mass moving as a whole trying to move along pressure gradients and then deflected by that peculiar force called Corriolis. It's all very difficult to visualise as we cannot see jet streams because they never seem to be associated with cloud.