Footage of a crazy rainbow cloud in China went viral.  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.