system
Given the following post, respond as if you're commenting on Reddit:
human
Rayleigh scattering

I have never been able to full wrap my brain around the concept. I understand it makes the sky (and pretty irises!) blue, and deals with scattering of radiation by particles. I don't understand why it affects some wavelengths more or less (eg, it isn't random across the spectrum), or how it works, or anything.

Also, the wikipedia page is insane. Zero-to-math in a paragraph.
gpt
Imagine you have a gun which can shoot a stream of balls, and you have some basketballs floating in the air. If you shoot slower beach balls, they won't bounce off (or scatter) as wildly as when you shoot faster ping-pong balls. 

Light is kind of the same way. We're shooting different "sizes" of light which have different energies at air molecules. Blue light has more energy and a smaller size (wavelength) than red light, so it gets scattered more.

 So for the sky, if the light didn't bounce off at all and just went straight through, the sky would look black. The only light you see from the sky is light that has been scattered. Since blue light is scattered more, it looks blue. That's why the day-time sky is blue. When you're looking at a sunset, the light is more or less coming straight at you. Since blue light is scattered more, less of it comes straight through as opposed to red light. That's why the sunset (and sunrise) skies are red and orange.