It’s not often a leaking swimming pool is interesting, but this is extremely cool.
Reddit user Namaqq posted a GIF on the subreddit OddlySatyfing that shows water streaming out of a plastic swimming pool. At first glance, it looks like it's a still image or perhaps even frozen solid, but after he puts his hand in front of the flow, he reveals it was flowing all along.
So what’s going on here? Other than witchcraft, the best explanation is a phenomenon in fluid dynamics known as laminar flow. Essentially, this is where fluid travels in a regular path, whereby velocity and all other flow properties remain constant at all points in the fluid.
The opposite of this is turbulent flow, where different points of the fluid are moving at different velocities. This results in an irregular path of flow, which reflects light irregularly, and is what occurs when the guy sticks his hand in the seemingly motionless water stream.
[H/T: Science Alert]