system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are rainbows always curved?
gpt
Rainbows are actually circular, however, ol' earth gets in the way. But there's more to it, too.

The sun's light has travelled so far that it's coming basically straight at us, there are droplets of water in the air that splits the light apart into colors, and bounces them back towards you. However, there's only a certain area where the water can be where it's perfect for this.

The real reason, however, is because water droplets are round. So since when they're at a certain distance with light coming in at a certain angle, any droplets in that circle will project those colors to your eyes.