There’s an extraordinary, rather rare, optical phenomenon that goes by the name of a glory, called so no doubt because of its resemblance to a halo. It’s caused by the shadow of an airplane (or some other object) on some clouds, which shadow becomes encircled by rainbow-esque rings – almost like a rainbow that’s perfectly round (which, actually, does occur, but only in very rare circumstances), but this isn’t a full-circle rainbow, it’s a glory. Confused yet?!
Curiously, the airplane’s shadow in the middle can disappear, leaving just the glory. You can get to see such an effect from a plane (if you’re lucky) coming in to land in cloudy weather if you sit at a window that’s not facing the sun. Which is where we were sitting; and this glory showed itself upon the dense cloud cover below us. I hadn’t seen this mysterious optical phenomenon at such a height for ages. This one was probably due to the air being relatively clean and fresh =>