Rainbows

Perhaps my schooling was better than this lady's, but I recall learning about refraction in middle school science class, and perhaps earlier grades. The link is to a video of a lady videotaping her water sprinkler and assuming nefarious reasons there is a rainbow in the mist since she only recalls rainbows around the sun and moon (!) 20 years ago.

But that reminded me of a Christian story about rainbows that perhaps a grandmother told me. A rainbow, the story goes, is a sign of God's promise not to repeat the floods of Noah's Ark fame.

I wonder which explanation of a rainbow is more useful? I wonder which the lady in the video heard?