system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do rainbows seem to have individual bands of color as opposed to a gradual color shift?
gpt
They don't have individual bands of color, and do have a gradual color shift. You tend to interpret the gradual shift as individual color bands, but that is largely your brain that is doing that.

You may be thinking of illustrations of a rainbow, where artists draw bands of color - but that is not what rainbows are like.