Does the coriolis effect affect the way toilet bowls spin in the northern and southern hemispheres?
Let's flush out the truth in this VERIFY question.
A few weeks ago, we verified a weather phenomenon called the coriolis effect, which makes tornadoes and hurricanes spin a certain direction in different hemispheres. The coriolis effect creates friction between the earth's axis of rotation and direction of motion. It makes tornadoes and hurricanes spin counterclockwise in the northern hemisphere and clockwise in the southern hemisphere.
That's what prompted Good Morning Show viewer Christy McNeal to ask a follow-up: "Did you know that water drains in those same directions in the two hemispheres, too? When you flush a toilet...it spins counterclockwise in the northern hemisphere and clockwise in the southern hemisphere?"
We consulted the award-winning science blog Live Science.
Live Science explains MIT fluid mechanic Ascher Shapiro ran an experiment in 1962 and concluded the coriolis force (effect) does affect water drainage.The University of Sydney did a similar experiment and concluded the same thing. But, the rotation is so miniscule, it's not noticeable with the naked eye. And, it is not the reason toilet bowls spin the way they do.
If toilet bowls spin different directions in different hemispheres, it's because the manufacturers made the jets point a certain direction.
In conclusion, the coriolis effect can affect toilet bowl spin, but it is slight. The direction they flush is simply a manufacturing decision.
by Meghann Mollerus