I guess so. The wind was quartering from behind (about 120 degrees off our track) - am I right in thinking the waves are always more or less perpendicular to the wind direction?
Not technically correct. Mountain wave is generally parallel to and downwind of the ridge or mountain range which triggers it, hence it may be at an angle to the wind direction and not necessarily directly behind (at 90 degrees) to the originating ridge. If there is visible cloud (lenticulars) then the quickest track out of the sink or lift is at 90 degrees to the line of the wave/cloud; in clear air it requires a bit of knowledge to work out which way to move.
