It's a very good relevant XKCD.

The title text is more directly applicable: If you ask "why are leaves green?" the usual answer is "because they're full of chlorophyll, and chlorophyll is green," even though "why does chlorophyll scatter green light?" is a great question too.

Better question: "Why is the sky usually blue but sometimes red?"

Talking specifically about sunsets, not apocalyptic wildfire smoke

"Don't breathe air, it has sharks in it! BLUE HAS SHARKS IN IT!" -The funny purple man

But it's an incomplete answer.

"air is invisible at short distances, blue at longer distances, and takes on red green and orange at sunset" would be better

https://theonion.com/after-obama-victory-shrieking-white-hot-sphere-of-pure-1819595330/

The reason the sun appears to be yellow is the same reason that the sky appears to be blue.

Blue light is scattered more by the air in the atmosphere than other wavelengths. Remove blue from white light and you get yellow. So the light coming from the sun that isn't scattered and dispersed through the sky (making the sky look blue) is yellow.

Neither water is blue

They take us for absolute fools

That's from plants that get their air mostly from the shade and sunsets, so obviously they'd be less yellow and more dark and red.

There's also an extremely tiny percent of plants that are entirely white, they don't get their energy through photosynthesis but instead a parasitic relationship of fungi and other plants.

Blue waves fast Red waves slow

Easy as

The thing is it's kinda right, just lacking detail