cough We were smoking a lot of... various things. I had setup a chill room that didn't have any air conditioning (so it was actually very hot; a hot box if you will). Just a small room where smoke would accumulate.
At any rate, I got very good at blowing smoke rings. In the still room, you could blow a smoke ring and it would expand for about a minute before dissipating. The more substantial rings would do something really crazy. They'd spawn a new, smaller ring, but going the opposite direction. I believe this was only the case if the ring was blown upward.
I don't know if this is related to the Two Vortex Ring Collision experiment, but it was definitely fun to watch!
This comment would have been better with a whiteboard.
Actually, I think you nailed it. I'm no physicist, but you made the mechanism behind it very clear and intuitive :)
That said, I wonder if such an experiment would be better with PIV or even Schlieren as there would be no need to refill the tank each time.
Hopefully these videos and the specially built machine helps additional scientists to study this effect and come up with more answers and conclusions about what's going on here, as it still seems largely shrouded in mystery.
I mean, look at this! https://twitter.com/smartereveryday/status/10084779939482828...