To establish whether or not the clockwise-anticlockwise spin of water going down a drain being different in the northern and southern hemispheres is true or not, let's conduct a survey.
I suggest we use the kitchen sink - because there's not as much variation in design as there is with bathroom sinks.
Where do you live (ie northern or southern hemisphere) and which direction does your water spin? Clockwise or anti-clockwise?
I'm no expert so just to complicate things a bit more
I think it all has to do with the way the air travels around the High and Low pressure systems. It travels in different directions depending on your hemishpere. Check the isobar maps on a weather map
Does that help?
edit: btw you cannot change the direction the water spins draining out of the sink I have tried
Sometimes it goes clockwise, on other drains it spins counter(anti) - clockwise.
The spin direction is influenced by a multitude of factors such as the geometry of the sink, initial conditions, stuff floating in the water etc, etc. So even in the same sink, the water can possibly spin in either direction.
Its true that the Coriolis force determines the spin direction of rotating systems. However this only applies to large entities such as depressions and anti-cyclones. The Coriolis force would have a negligible effect on water draining from a sink and other factors would be dominant.
Dr Karl Kruszelnicki the Australian scientist, author and broadcaster who features regularly on BBC Radio 5's Up All Night program and the ABC's Triple J station has a bee in his bonnet about this, and an explanation of the Coriolis force probably appears in one of the many books which he is always "plugging"!
I did chores, went to work, went shopping, and made dinner... I just sat down, but Im totally going to go do this for you.... gimme a few minutes.
The coriolis force isn't high enough, it's going to depend on the design of the sink. But, if you could stop water flow using a stopper and then when it's all steady let it flow, maybe you could try it out. Gonna follow this thread
That's why I suggested the kitchen sink, lobobrandon. I figure at some time we will all have a sink full of dishwater to let drain from the sink. We might have to wait a few days for those with a dishwashing machine to have reason to fill their sinks with still water though. lol.
It is true--I learned this years ago in Earth Science and geology classes. The water spins counter-clockwise in the northern hemisphere, and clockwise in the southern. Lobobrandon is correct--the term is "the coriolis force."
In fact, there is an old logic puzzle about a stowaway on a cargo ship who got caught. The captain locked him in an inside room, and told him that if the fellow could determine when they crossed the equator, he could have free passage. And the guy did. All that was in the room was a sink, bunk and toilet. And he used exactly that means...kept filling the sink, and watching for the direction of spin of the exiting water...got his free passage.
(Toilets don't count, because they can be designed to flush in either direction by virtue of the shape of the bowl and inlet duct angles.)
I love the image of the stowaway, DzyMsLizzy. I hope he had a tap over the sink and wasn't forced to collect his water from the toilet!
I remember being taught that water flows down the drain in opposite directions when I was at school. It is maddening that I have lived in both the northern and southern hemispheres and never thought to actually pay enough attention to check for myself.
I am guilty of telling my kids when we lived in the UK that the water in Australia goes down the sink the opposite way. To be honest, I've always just pulled the plug and walked away, or been too busy cleaning the sink to watch the water's path down the drain. lol.
Yes - it's true, but as lobobrandon said, the Coriolis force isn't high enough. It works at ocean level, not at sink level.
Perhaps then we should also add "How high above sea level." (Anyone with a navman, garman, gps-of-some-description can probably press a button to find out their precise height above sea level.)
I know how high above sea level I live. I just need to wait for my next lot of washing up before I double-check my spin direction.
Ah - sorry. I should have chosen my words better. By 'ocean level' I didn't mean at sea level, I meant ocean SIZE. Apparently, it needs a huge ocean-sized body of water for the effect to be observed.
According to Wikipedia's 'coriolis' entry
" Because the Earth completes only one rotation per day, the Coriolis force is quite small, and its effects generally become noticeable only for motions occurring over large distances and long periods of time, such as large-scale movement of air in the atmosphere or water in the ocean."
"Water rotation in home bathrooms under normal circumstances is not related to the Coriolis effect or to the rotation of the earth, and no consistent difference in rotation direction between toilets in the Northern and Southern Hemispheres can be observed. The formation of a vortex over the plug hole may be explained by the conservation of angular momentum." (whatever that means).
Hmmm. Then why does water spin when it goes down a plug hole? If it is not the Coriolis effect, what is it? Can anyone explain what "the conservation of angular momentum" means?
I'd be surprised if anyone has ever surveyed as many people as we have the potential to reach. I'm still interested in collecting the data. Not sure what we'll learn from it, but there's no harm in exploring an interesting question like this.
I'm in the UK - ours goes clockwise down the drain - I'm curious now!
There's going to be an immediate water shortage all over the world and it's going to be our fault.
Beth, you never cease to amaze me with your brilliance!
I like that choice of words, it's much nicer than stupidity.
Which way does your water spin, Beth37?
I didn't do it yet. Ive let you down. Im pretty sure it goes clock-wise, but Ill let you know.
I'll bite my lip until it bleeds before I will complain about it ... but tonight my husband washed the dishes and let the water out when I wasn't looking!!!
For those who don't know, we live off-grid, harvest our own rainwater, and we're in the middle of really bad bushfires. Three reasons why I won't be filling the sink again tonight. In the interests of water conservation (despite my curiosity) I'll have to wait until tomorrow.
I saw a demonstration of it on TV in an African country that straddles the equator (I can't remember which country). It's set up for tourists right at the equator. What they do is have a bowl filled with water with a tiny hole at the bottom that lets the water leak out slowly. Then they float a matchstick on the surface and it begins to spin in a certain direction. Then while holding the bowl, they take a few steps across the equator and the match then begins to rotate in the opposite direction. It looks convincing but scientists say it's just a trick and nothing to do with moving from one hemisphere to the other.
LTM, I'm in the Southern Hemisphere and both the kitchen sink and bath water did appear to go down counter-clockwise. I always did lean to the left.
However, apparently even tiny imperfections in the stink can affect the direction, so...meh, not conclusive I suppose.
Thanks, Ella Quirk.
That's one counter-clockwise for the SH and Wacky Mummy's clockwise in the NH.
Water will go down a drain in either direction in either hemisphere because the direction of flow has nothing to do with Coriolis or rotation and everything to do with the shape of the basin or toilet.
Mine appears to go straight down without any real swing in either direction although that might have something to do with our strange off-grid plumbing. Tried it a couple of times now.
I'd seen this claim demonstrated in a BBC news video, and thought it was true myself.
Following that experiment, I tried using a toothpick in the bathroom sink, and it started turning when the water was almost gone. It turned clockwise. But I'm in the northern hemisphere. Hm.
So then I did some hunting.
Here's a page debunking "clockwise/anticlockwise down the drain" experiments. Astronomer Phil Plait also explains how the Coriolis effect works and why it works with hurricanes but NOT the water in your sink.
Also, Phil Plait took a look at a video similar to the one above and figured out the trick being used to "fake" the Coriolis effect in the equator demo.
In the BBC video I linked to above, I'm not sure whether the faker is using the trick Plait spotted, or whether it's the way the matchstick is placed, or whether it's the fact that the basins are tilted for the "northern/southern hemisphere" demos.
With large storms, the Coriolis effect IS visible:
Hurricane Isabel, northern hemisphere:
Cyclone Yasi, southern hemisphere:
Thanks for your research. It's worthy of a hub! lol.
And even at such large scale, the cyclones/typhoons/hurricanes will not form within 10 degrees south and 10 degrees north as the Coriolis force tends to approach zero the closer you get to the equator.
Interesting subject: however, I think there are too many variables on our sinks and basins. My kitchen sink drains clockwise, and my bathroom basin drains counter-clockwise. Doesn't the level or tilt of the sink influence the direction as well?
It doesn't spin...it doesn't do anything at all...just sits there...festering...with hair floating up from the drain...it's slowly taking possession of my home...I've had to close up the kitchen because of the ominous bubbles,belches,and smells...I suppose I'll have to close the living room next...I keep waiting for Alfred Hitchcock to come round the corner...it's getting dark now.........
I really wanted to participate in this forum when I saw it last night but since I do not have a kitchen sink I figured no one wanted to hear from me. Since I do live near the equator, however, I decided to participate and flushed my toilet. The water went straight down, neither clockwise or counterclockwise.
I do not know if that means anything. I am eagerly waiting other fascinating scientific experiments in which I can partcipate!!
Straight down! Crazy talk. That's not even an option.
We could try a scientific experiment assessing the results of alternative therapies on dogs with arthritis. Shall we start with NZ green-lipped mussels? Hmm ... you don't have a kitchen sink. I'm thinking many more won't have arthritic dogs.
Guess that elimates that idea. lol
This was "solved" quite a while ago...
http://www.scientificamerican.com/artic … nally-sett
Hi, relache. I'm not quite sure how that article 'solves' the mystery. I followed your link and now I'm back to square one.
Just when I was accepting the view that the Coriolis effect does not have any role in bathtubs or kitchen sinks, I've now learned that a staff geologist with the Louisiana Geological Survey says, "the rotation of the earth gives rise to an effect that tends to accelerate draining water in a clockwise direction in the Northern hemisphere and counterclockwise in the Southern."
Plus a physicist at George Mason University says ...
"If all extraneous influences (including air currents) can be reduced below a certain level, one apparently can observe that drains do consistently drain in different directions in the two hemispheres."
It seems that most people are in agreement that basin shape and other factors generally overpower the Coriolis effect, but the scientists quoted in the scientificamerican article still maintain there should be an opposite direction when draining water in the two hemispheres.
So ... I'm back at my original question, lol.
The article said this: If you had an ideal scientific situation free of other influences, and with a specially prepared bathtub, the water would drain clockwise in the northern hemisphere and anticlockwise in the southern hemisphere.
As for this question, the correct answer is either clockwise or anticlockwise regardless of whether you are in the southern hemisphere or northern hemisphere.
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