We all know that wind must flow downward before it rebounds to form a soarable wave, right? And beneath every wave’s crest there’s rotor… Yes well, for every atmospheric phenomenon that obeys a textbook drawing there are more that stray from it or defy it outright. I’ve soared in wave with no apparent rotor beneath it, and gone two miles up in rotor that seemed to have no wave above it. Such anomalies should not be ignored or discarded as junk data, but valued as the scent of fuller understanding yet to be gained.
Diagrams of wave usually show an initial downward flow hugging the hill like a blanket before curving back up from the bottom, with rotor churning a mile or more downwind, directly below the ‘primary’ wave’s crest. That’s not always how it works though. Living ten years on a mountain that regularly generates classic wave, but flying daily only spring, summer and fall, I experienced more wave days from the source itself than from any cockpit, and am very sure of this uncertainty.
The ridge is a mile and a half long on top, standing quite perpendicular to frontal westerlies. Ski trails run more than 2000 vertical feet down the lee slope, which I might yoyo ten to twenty times every day of winter, always observing weather on the ride back up. Often as not on wave days, surface wind flowed up that slope, meaning primary rotor in direct contact with the hill.
So what’s the difference? Or is there a difference?
In my expert opinion, maybe. When surface wind flowed uphill the wave’s first crest would sit directly over the base parking lot, but when wind flowed downslope it followed the standard schematic, feeding a ‘primary’ wave (generally larger)
where it’s supposed to be some distance downwind.
Of course there were also many wave days with no wind at all near the surface. About them I have, quite confidently, no opinion. Swear to Gaia.
Ultimately, the wave itself has no reason to care where its rotor is, or even if it exists. Like all wild creatures, wave simply does what it’s impelled to. Perhaps that’s the main lesson it has to teach us…