Increase wind speed steadily with increasing altitude. Air in a mountain lee wave spends half its time ascending and the other half descending. You seek the lift band, the portion of the wave that's moving upwards. The lift band is like an elevator shaft that tilts into the wind. At extreme heights, soaring pilots can sometimes look straight down on the peak that caused their wave.
Rotor clouds spin beneath the smooth bottom of lenticulars.
In most cases they cause turbulence that's unpleasant but not deadly. But they can tear a plane to smithereens. Rotors are the suspected cause of several unexplained airline crashes. Round on the top and flat on the bottom, they have been occasionally mistaken for flying saucers. But a mountain's shape also influences the wave's size.