We send you off into the long weekend with this fabulous sight. Footage of a rainbow cloud in China. If you haven’t seen it, it almost looks fake, but it’s not. Here’s the science behind it . . . It’s called a pileus cloud or “scarf cloud.” Basically, a wispy cloud forms above a cumulus cloud. Then light gets diffracted by tiny ice crystals inside it, and that’s what causes the rainbow effect. In this case, the sun was setting right behind it.