Bottle Tornado

With the right motion, you can create a vortex of water between two bottles. This makes it possible to see how tornadoes and other swirling flows form.

The Science Behind It

The vortex forms because of centrifugal force: rotating water is pushed outward against the bottle wall, creating a channel of air in the middle—the characteristic funnel of a tornado. Air can flow upward through this channel while water flows downward, instead of the two blocking each other. The same principle helps create real tornadoes and whirlpools in drains.