Mountain wave and rotor
Jay Sata and Thomas Coupling, and other rotorheads, or power pilots who get nervous flying in mountains, may I recommend a trip to the Deeside Gliding Club in Scotland to broaden your horizons? (Have a look at their website!) Or visit one of the French clubs that can introduce you to Alpine soaring....
No, we don't fly IFR in gliders very often, or not on purpose, but we do use ridge lift and mountain wave to maintain flight, and so acquire with experience a pretty good idea of where is lift and where is sink! And where is rotor....relative to wave bars....clouds that will mark the rising air on the windward side, and the horrible sink or rotor on the lee side of the bar. The wave bar cloud formation, usually saussage shaped, is distinguished by not traveling with the wind, but remaining fairly stationary over the ground, DOWNWIND from the mountain ridge that has created the wave bar. I like to ask beginners to think of a rock in the river, and the ripple that forms DOWNSTREAM from the rock. It (and the wave cloud) will remain fairly stationary and usually has at least three wave bar formations, possibly more in succession less powerful.
When the usual wind from the west comes up against a mountain range, it moves up the slope, creating what we glider pilots call ridge lift. Conversely, on the other side you will find sink, and turbulence. But a strong steady wind from the west will also produce mountain wave on the downwind side of the mountain ridge. So a knowlege of general conditions and prevailing wind direction can be useful.
Glider pilots have achieved over 50,000 feet in mountain wave (with oxygen!!) I managed to get to 20,300 feet at Deeside. That was enough for me.