system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Mountains are brown, yellow, and green and definitely not blue or purple, yet they look purplish-blue from far away. Why is this?

Noticed it on my drive home in the desert...never occurred to me to actually ask why...
gpt
Because if they are far away, there's more stuff i.e. atmosphere between you and the mountains and thus it gets a slight bluish tint. It's the same reason why the sky is blue. Blue wavelengths are scattered less easily than red ones so they 'dominate'.

You'll notice that not only mountains appear bluish at a distance but really everything does.