Ever wondered what makes swimming pool water blue?
If you've ever filled up a glass from the tap, you know it's clear, so it's natural to wonder what makes swimming pool water blue once it hits the deep end. It's one of those weird tricks of nature that we mostly take for granted until we're sitting on the steps of a pool on a sunny day. You'd think if you put clear water in a big hole, it would just stay clear, but physics—and a little bit of chemistry—has other plans. ...