First helicopter landing on Mt Everest

I don't think that wave lift is described as orthographic.

Wave is a gravity/compression phenomonon and ridge lift is just wind being
forced up hill.

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.

A great book on waves and soaring in them is Exploring the Monster which
chronicles the Sierra Wave Project in the 1950s.

Mike
MU-2


"Peter Duniho" wrote in message
...
"Mike Rapoport" wrote in message
nk.net...
I was thinking more about ridge lift. I know that ridge lift has been
used to fly 152s over Mt Kilimanjaro 19,000+'

Heh...I lump that in with wave. It's all orographic lifting, right?

I can see why some folks would prefer to not use the terms
interchangeably, or in a sub/superset relationship. I don't generally
make a distinction though; anywhere the wind is affected vertically by
topography, I refer to as "wave".

In any case, even if some meteorological phenomena was used (whatever one
might want to call it), it's still a pretty impressive demonstration.

Pete

"Mike Rapoport" wrote in message
k.net...
I don't think that wave lift is described as orthographic.

That's "orographic".

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

In article ,
"Peter Duniho" wrote:


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

Is this to say that in this wave system the air motion, at least at
certain altitude levels, has vertical velocity components that oscillate
between positive and negative values with increasing downwind distance?
-- maybe with something like a highly damped sinusoidal variation if
plotted vs downwind distance?

Even with my feeble to nonexistent knowledge of fluid mechanics and
aerodynamics I can picture that.

If so, what's the approximate horizontal period of the oscillation?
Would it happen also with a thin vertical wall?

"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