We were visiting with friends on the porch when all conversation was stopped to admire a rainbow.

The colors are usually vivid. A second rainbow emerged with the color spectrum reversed. I had never noticed this before and had to look up the cause.

It involves light passing through droplets more than once. I read that there can be triple rainbows and sometimes a hint of a forth.
I am amazed that I never noticed this about a double rainbow. Next time you see one. Look for ROYGBIV and VIBGYOR.

FLOW