Ok scientists, why does this phenomenon happen?...
https://mstdn.social/@stux/109450615803341213
(It's a toot by @stux showing a thin layer of water flowing over the rim of a small dam (maybe .5 meters high). When a stick is touched onto the layer of flowing water, it changes it's flow pattern and instead of clicking to the downward side of the wall of the dam it flows outward, away from the dam wall and directly into the body of water downstream from the dam. At first it changes right at the spot where the stick touches, but then in a cascading fashion the new flow pattern ripples all the way across the dam.)
