Originally Posted by
VMC-on-top
It was a typo!
Windspeed x 100ft.
Everyone happy?
Far from it! That may work as an approximation for avoiding low level turbulence but it won't work for wave (and associated rotor). Mountain Wave can go as low as ground level and right the way up to the heights described elsewhere. In gliding you soon learn that wherever there's air going up, there'll be air going down too. You don't want to be in the downdraught near the ground or caught in between the opposing layers!