Today's EPOD may have solved the mystery for me. I think the S-shaped rainbow I saw above the mountain may have been part of an upper tangent arc--similar to the one depicted in the EPOD photo. How exciting to have my experience explained after so long!
April 6, 2012
Years ago, when I was still a student at the University of Utah, I went snowshoeing with my friend Jon Richardson in Little Cottonwood Canyon (at right is a photo I took looking down the canyon in autumn). It was a beautiful sunny day and we worked ourselves into a vigorous sweat trudging up the wooded mountain side through feet of snow. After thoroughly exhausting ourselves we returned to the car to catch our breath. I looked toward the top of the mountain and was stunned when I saw a veritable blizzard of snowy ice crystals swirling around in the blue sky above us. In the midst of those crystals was a rainbow that snaked through the squall like a giant stretched-out "S". I couldn't believe my eyes. I thought it was some sort of trick. I had no idea that rainbows could contort themselves into anything but a single gentle curve. That was back before I had a handy digital camera to tote around and I have nothing to show for the event but my own (undoubtedly imperfect) memory.