This morning, taking the Sunset Highway from Portland through Beaverton out to Hillsboro, I was treated to a full double rainbow on account of the clear sunrise behind me and a vigorous rain squall in my path. I noticed something as the rainbow “moved” along with the car: It seemed to exist at a distance but also pass in front of objects. That’s when I realized something I probably should have picked up a long time ago.
I always think of a rainbow as a structure which exists as a flat band “over there” somewhere, but in fact any bunch of raindrops at the correct angle from my eyes can be part of that particular illusion. It is, in fact, built by a cone (or section of a cone) in which there’s sufficient water vapor and/or raindrops.
In other words, with apologies to Jim Henson: One day I found it, the rainbow cone action.