A Conversation for The Hairy Ball Theorem

Tornado on a hairy ball

Post 1


That is a good analogy for a tornado: hair sticking straight up. Is there a mathematical reason why wind must twist round a tornado (apart from its name) while it's not necessary for hair to twist round a sticking-up tuft?

Tornado on a hairy ball

Post 2

Gnomon - time to move on

Just seen this. It's to do with the rotation of the earth. This causes airflows moving away from the Equator to bend to the East and airflows moving towards the Equator to bend to the west.

This is known as the Coriolis effect. If there is no wind at all, all the air on the earth is moving east to keep up with the rotating Earth (except at the pole). Wind at the equator is moving faster than wind in the northern latitudes. If there is a wind blowing north from the Equator, when it gets to the north it still has its equatorial eastern speed as well, so it ends up going further east.

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