New video showing an example of conservation of angular momentum using fire.



The idea that "hot air rises" is a pet peeve of mine. It's true, but there is nothing gravity-defying about hot air. It's the fact that colder air is more dense which displaces the hot air upward.

Anyway, with the hot air going upward, it draws in cool air from the sides. As that inrushing air passes through the spinning screen, it gets a little rotational push.

Just like an ice skater spinning slowly with their arms extended, but spinning quickly when their arms are in, the rotation of the cool inrushing air increases as it approaches the rotational axis. The result is that the hot air rushing upward is now somewhat contained in a vertical column.