First helicopter landing on Mt Everest

"Peter Duniho" wrote in message
...
"Mike Rapoport" wrote in message
k.net...
Wave is a gravity/compression phenomonon and ridge lift is just wind
being forced up hill.

Wave only happens as a result of orographic lifting. IMHO, the fact that
some of it occurs downwind of the hill is irrelevant to the fact that it's
part and parcel of the whole effect of the hill. The ridge lift is simply
the first bump in the whole wave.

Another distinction is that wave lift at mountaintop level is several
miles downwind of the mountain and ridge lift is upwind and immediately
adjacent to the lifting surface.

The wave lift downstream of the hill is just a single component of an
entire phenomenon. It's just an updraft portion of a complete wave
system, a system that starts upwind of the hill.

Pete


I don't want to beat this to death but no glider pilot in the world would
equate ridge lift with a mountain wave system. Ridge lift occurs any time
that wind blows over rising terrain and it does not extend much obove the
ridge top. A mountain wave system is a function of numerous variables
including increasing wind speed with alititude, angle between the direction
of the wind and the ridge. It requires stable air. The correct term is
actually gravity lee wave and it all starts *after* the obstacle.

So yes, you need wind blowing up hill to produce a gravity wave but the wave
itself is down wind of the ridge.


Mike
MU-2