Australian Toilets Don't Flush Backwards Because of the Coriolis Effect

Toilet image via Shutterstock

File under "News to Me": you know that old story about how northern hemisphere toilets flush counter-clockwise, and southern hemisphere toilets (and buckets, drains, and such) flush clockwise, due to the Coriolis effect? It's bogus! Today I learned that while the Coriolis effect is significant for hurricanes, it's not strong enough to make toilets flush in different directions at different points on the Earth. The real cause of "backwards"-flushing toilets is just that the water jets point in the opposite direction. Mind blown. (Mind blown even more because this was the inciting event on a Simpsons episode, and everybody knows cartoons are never wrong.)

Let's Talk Science

So there is indeed a Coriolis effect, and we see it on grand scales -- hurricanes in different hemispheres tend to rotate in different directions, because the underlying Earth is spinning, and the effect is exaggerated as you move farther from the equator. This Penn State science page by Professor of Meteorology Alistair B. Fraser explains:

On the scale of hurricanes and large mid-latitude storms, the Coriolis force causes the air to rotate around a low pressure center in a cyclonic direction. Indeed, the term cyclonic not only means that the fluid (air or water) rotates in the same direction as the underlying Earth, but also that the rotation of the fluid is due to the rotation of the Earth. Thus, the air flowing around a hurricane spins counter-clockwise in the northern hemisphere, and clockwise in the southern hemisphere (as does the Earth, itself). In both hemispheres, this rotation is deemed cyclonic. If the Earth did not rotate, the air would flow directly in towards the low pressure center, but on a spinning Earth, the Coriolis force causes that air to be deviated with the result that it travels around the low pressure center.

So it works on large scales. But on small scales (like in your toilet, sink, or bucket), the rotation of the Earth itself (at a decidedly pokey rate of one rotation per day) is much weaker than other forces -- like the force of water jets in a toilet, or the force of water hitting slopes in a sink.

The Pole to Pole Problem

In tracking down where this drain-direction myth originated and how it got so firmly lodged in the heads of people like me, many sources discuss the (otherwise awesome) Michael Palin documentary Pole to Pole, in which Palin visits the equator in Kenya and observes a tourist trap in which a man "demonstrates" (via fakery) the draining of water in different ways on the equator itself, and just north and south of it. Palin doesn't point out that it's fake. I remember seeing this documentary when it came out, and it may be where I picked up the notion -- it seems like such an appealing demonstration of science, such an "ah-ha!" moment that of course the rotation of the Earth should cause such changes in draining water! We're all tiny ants on a huge spinning globe! What wonders! Sadly, it's BS. Again, Fraser has a good write-up; here's a snippet:

[T]he faker must be forcing the rotation by other means, and by a sufficiently unobtrusive way that the busloads of tourists do not spot the means. Indeed, a colleague of mine, who witnessed the performance first hand and knew it was a cheat, was not able to spot how the fraud was perpetrated. (It is an interesting sidelight that when back on the bus, he informed his fellow tourists that they had just witnessed fakery --- the Earth did not cause the rotation they had just seen --- there was widespread disappointment. The tourists preferred the fantasy to the reality.)

Fraser proceeds to explain how you can fake it yourself.

The Plot Thickens

According to various sources, it is possible to demonstrate a Coriolis effect on water on a small scale, but only under extremely controlled circumstances -- involving predictably shaped water vessels, long periods of time of waiting for water to become as still as possible, carefully removing a stopper in the bottom of the vessel without adding spin, and other such crazy stuff. But in your typical toilet or sink, the Coriolis force is so small as to be undetectable relative to other forces. Even holding a bowl of water and turning around introduces sufficient spin to get things going in one direction or another.

A Fun Experiment

Go to your bathroom now and observe water going down the drain -- any drain you want. Depending on the efficiency of your plumbing, you may need to stop up the drain, fill the basin, then unplug it and wait. (It might also help to have something lightweight floating in there, to mark any motion -- a few bits of tissue may work, or a matchstick or two.) Observe whether the draining water forms a clockwise or counter-clockwise spiral. Go ahead, I'll wait. Now check all the other drains you can find. Do they match? In my (admittedly unscientific) testing just now, one sink drained clockwise, the other counter-clockwise, one didn't have an easily observable spin (it's small), and the toilet was also counter-clockwise, clearly due to the position of its water jets. Well. There you go: science in action.

(Via Steven Frank, via Snopes. Note that we covered this topic back in 2007 as well.)

Mysterious 'Hypatia Stone' Is Like Nothing Else in Our Solar System

In 1996, Egyptian geologist Aly Barakat discovered a tiny, one-ounce stone in the eastern Sahara. Ever since, scientists have been trying to figure out where exactly the mysterious pebble originated. As Popular Mechanics reports, it probably wasn't anywhere near Earth. A new study in Geochimica et Cosmochimica Acta finds that the micro-compounds in the rock don't match anything we've ever found in our solar system.

Scientists have known for several years that the fragment, known as the Hypatia stone, was extraterrestrial in origin. But this new study finds that it's even weirder than we thought. Led by University of Johannesburg geologists, the research team performed mineral analyses on the microdiamond-studded rock that showed that it is made of matter that predates the existence of our Sun or any of the planets in the solar system. And, its chemical composition doesn't resemble anything we've found on Earth or in comets or meteorites we have studied.

Lead researcher Jan Kramers told Popular Mechanics that the rock was likely created in the early solar nebula, a giant cloud of homogenous interstellar dust from which the Sun and its planets formed. While some of the basic materials in the pebble are found on Earth—carbon, aluminum, iron, silicon—they exist in wildly different ratios than materials we've seen before. Researchers believe the rock's microscopic diamonds were created by the shock of the impact with Earth's atmosphere or crust.

"When Hypatia was first found to be extraterrestrial, it was a sensation, but these latest results are opening up even bigger questions about its origins," as study co-author Marco Andreoli said in a press release.

The study suggests the early solar nebula may not have been as homogenous as we thought. "If Hypatia itself is not presolar, [some of its chemical] features indicate that the solar nebula wasn't the same kind of dust everywhere—which starts tugging at the generally accepted view of the formation of our solar system," Kramer said.

The researchers plan to further probe the rock's origins, hopefully solving some of the puzzles this study has presented.

[h/t Popular Mechanics]

Ocean Waves Are Powerful Enough to Toss Enormous Boulders Onto Land, Study Finds

During the winter of 2013-2014, the UK and Ireland were buffeted by a number of unusually powerful storms, causing widespread floods, landslides, and coastal evacuations. But the impact of the storm season stretched far beyond its effect on urban areas, as a new study in Earth-Science Reviews details. As we spotted on Boing Boing, geoscientists from Williams College in Massachusetts found that the storms had an enormous influence on the remote, uninhabited coast of western Ireland—one that shows the sheer power of ocean waves in a whole new light.

The rugged terrain of Ireland’s western coast includes gigantic ocean boulders located just off a coastline protected by high, steep cliffs. These massive rocks can weigh hundreds of tons, but a strong-enough wave can dislodge them, hurling them out of the ocean entirely. In some cases, these boulders are now located more than 950 feet inland. Though previous research has hypothesized that it often takes tsunami-strength waves to move such heavy rocks onto land, this study finds that the severe storms of the 2013-2014 season were more than capable.

Studying boulder deposits in Ireland’s County Mayo and County Clare, the Williams College team recorded two massive boulders—one weighing around 680 tons and one weighing about 520 tons—moving significantly during that winter, shifting more than 11 and 13 feet, respectively. That may not sound like a significant distance at first glance, but for some perspective, consider that a blue whale weighs about 150 tons. The larger of these two boulders weighs more than four blue whales.

Smaller boulders (relatively speaking) traveled much farther. The biggest boulder movement they observed was more than 310 feet—for a boulder that weighed more than 44 tons.

These boulder deposits "represent the inland transfer of extraordinary wave energies," the researchers write. "[Because they] record the highest energy coastal processes, they are key elements in trying to model and forecast interactions between waves and coasts." Those models are becoming more important as climate change increases the frequency and severity of storms.

[h/t Boing Boing]


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