Crazy Pool Vortex

Physics Girl shows us what happens when you are lucky enough to have your own pool, a plate, and a sunny, windless day. All that would be nice even if you didn’t try this physics experiment! She keeps saying “This is really cool!” but she’s absolutely right. I had no idea fluids would move that way, and when she added food coloring, my mind was blown. In the comments, she expressed surprise that it worked out as well as it did, even though she already knew the physics involved. Physics Girl has quite a few other really neat videos at her YouTube channel. (via Metafilter)