A black rainbow is a real thing; it appears where water drops reflect light away from the viewer. : r/Damnthatsinteresting

Rainbow on (behind) the horizon. Origin is behind the curve : r

Color and Vision

How to Make a Rainbow at Home: Fun Science Projects for Kids

Scattering of light by rain water causes a rainbow. While raining

Just a single a single atom trapped between electrical fields. : r

If Rainbows are caused by light refracting through water droplets

Exploration into the Physics of Rainbows

Rainbows on exoplanets reveal the presence of water - SRON

Free AstroScience - This is what happens when a rainbow falls

There Is More to a Rainbow than Meets the Eye