Everybody loves rainbows— they fascinate us, we stop to admire them, and we soak in their color and magnificence. Songs are written about them. Judy Garland reminded us: Somewhere over the rainbow Way up high, There’s a land that I heard of Once in a lullaby. And way up high is the only place to encounter the phenomenon of the circular rainbow. Mountaineers, pilots and airplane passengers may be lucky enough to see one, the complete…