[no-s]

Whilst flying a sailplane I’ve seen a rotor cloud ( a kind turbulence associated with mountain wave soaring ) form in a fraction of a second. The first sign of it was a streak of cloud rising and curling over.

It was in front of me and I dived to get under it, passing through massive sink. Fortunately I found some ridge lift nearby and was able to make it back to safety.

Many years ago sailplane pilots flying in a contest near Marfa Texas were enjoying some strong updrafts in clear air and suddenly discovered they were in a coalescing strong tornado.