You've probably seen a rainbow before. When sunlight passes through raindrops in the sky, the light is split into the colors of the rainbow. If you have the right angle, you can see the full band of the rainbow stretch across the sky. Sometimes, you might even catch its mirror image, creating a full double rainbow. Here's a twist, have you ever seen a rainbow in a cloud?

Here's a picture Chief Meteorologist Marc Weinberg took on Sunday! Wild-looking, isn’t it? So, what is it, and how in the world does something like that happen?

Image: Marc Weinberg

This can happen because of something called cloud iridescence. It usually happens in altocumulus, cirrocumulus, lenticular and cirrus clouds. Iridescent clouds happen because of diffraction – a phenomenon that occurs when small water droplets or small ice crystals scatter the sun's light.

Cloud iridescence is relatively rare. The cloud must be thin and have lots of water droplets or ice crystals of about the same size. When that happens, the sun's rays encounter just a few droplets at at time. For this reason, semi-transparent clouds or clouds that are just forming are the ones most likely to have iridescence.

Image: Kim Burroughs McIntyre via Facebook