-- Stunning video captured a rainbow in the clouds over Ribeirao Claro, Brazil, in a meteorological phenomenon known as cloud iridescence.
Iridescence like this happens when the clouds are very thin and are made of similar-sized water droplets.
What you’re seeing, essentially, is part of a corona -- when a rainbow-like halo engulfs the sun or the moon -- and the bands and colors change as the cloud evolves.
Iridescence is most often seen close to the sun.
It's usually spotted when part of a cloud is forming because that's when all of the water droplets have a similar history and similar size.