BOW WAVE

Unlike 'classic' wave downwind of high ground, we find our bow wave UPwind where the whole atmosphere seems to pile up before surging over the San Gabriel crest.   Although this phenomenon rarely forms clouds, we have seen (and photographed) as many as three lenticulars arrayed over the flat desert, just like ordinary harmonics in reverse.   There is one important distinction, however.   While 'classic' waves tend to be more or less stationary, bow waves often flow through, beginning far upwind, drifting toward the mountains, and then breaking over the crest in a manner more similar to surf.   When this happens a sailplane soaring in ridge lift may suddenly encounter sink (or even rotor) on the windward slope.   If so, the thing to do is glide directly upwind in search of the next arriving bow wave.   Also, if you're towing toward the mountain and enter smooth lift before getting there, the best guess might be to release where you are and either climb or at least maintain height while that wave drifts onto the hill.   (Towing beyond that lift and closer to the hill might put you in wave sink, too low to get back upwind into the lift you already had...)Fact is we need more research on this intriguing topic, so YOU should come out when the north wind blows and help us gather DATA!