Water draining from a sink spins clockwise. Same for water in a commode. That's how ships know when they've crossed the equator. The water stops spinning in one direction and goes in the other. The Navy gives a certificate to seamen who are aboard a vessel as it cross the equator.
Tornadoes, hurricanes and typhoons also spin clockwise. For that reason, these storms never cross from one hemisphere to the other.
Because things that spin work backwards in the Southern Hemisphere as opposed to the Northern Hemisphere is the reason no nation in the Southern Hemisphere has developed a nuclear bomb. They have their centrifuges running backward.
