The Coriolis Effect Test: two hemispheres, one sink


The Coriolis Effect Test: two hemispheres, one sink

Disproven! The Coriolis Effect does not make the water drain out a sink anti-clockwise in the Northern Hemisphere and clockwise in the Southern.

Have you taken the same sink to both hemispheres? If so: send in your data to add to mine.

Northern: Clockwise, clockwise, clockwise, clockwise, clockwise.
Southern: Anti-clockwise, anti-clockwise, clockwise, anti-clockwise, clockwise.

SmarterEveryDay: The Truth About Toilet Swirl – Northern Hemisphere

Veritasium: The Truth About Toilet Swirl – Southern Hemisphere

Thanks to my Patreon supporters who made this possible! Here are a random subset:

Ben White
Jade Bilkey
Scott Robinson
Amy Sandland
Mikko Manninen

If you’re wondering how I transported the sink from one hemisphere to the other: that is covered in the Patreon behind-the-scenes footage for this week. Support me on Patreon for as little as $1.11 and get access to all bonus content.

Huge thanks to Trent Burton who filmed the video in London, Simon Wright who filmed the Sydney footage and Jen Rogers who was the on-site runner and statistical consultant. Trent then nearly died trying to do the edit.

The sink was donated to a recycling centre in Sydney. It was last seen by the front door of Reverse Garbage (Addison Road, Marrickville, NSW). If anyone wants to buy the sink, it may still be there! If anyone checks on the sink let me know if you find it or not. Last known photo of the sink:

– It sounds like I say “Dustin” at one point instead of “Destin”, sorry about that. I got the wrong name wrong.
– Let me know if you spot anything else!

The photo of Earth was taken on 6 July 2017 by the Deep Space Climate Observatory (DSCOVR) satellite. Image by NASA.

Northern Hemisphere anti-clockwise storm is Hurricane Katrina from 2005. Image by NASA.

Souther Hemisphere clockwise storm is Cyclone Debbie from 2017. Image by NASA.

Training in the Fire by Twin Musicom is licensed under a Creative Commons Attribution licence (

Music by Howard Carter
Design and filming by Simon Wright
Filming and editing by Trunkman Productions
Additional help by Jen Rogers

MATT PARKER: Stand-up Mathematician
Maths book:
Nerdy maths toys:

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