h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I've always wondered who might have been the first person to notice that bathtubs and toilet bowls drain in an anti-clockwise rotation in the southern hemisphere.

It must have been very distressing. And did he have to go north of the equator again to be sure he wasn't just going crazy?

But by reminding you of this rather famous fact of Life on earth it does lead to the larger (much larger) question about weather systems.

Do High and Low pressure weather systems in the great "down under" rotate 'backwards' to what we have in the north? Or does a Low simply become a High and vice versa? Do South Pacific cyclones rotate the opposite way from North American tornadoes? And if not why not?


~jwf~

http://www.weatheronline.co.uk/feature/bb190202.htm

Low and high pressure are low and high pressure regardless of which hemisphere you're in.
A cyclone is like hurricane not a tornado. And cyclone can spin the same way as a hurricane, they've different names because of the Ocean they form over not way they spin.
Tornados can spin either way as they are formed by the collision of hot and cold air.

Yes they do. It's the Coriolis effect.

http://www.ems.psu.edu/~fraser/Bad/BadCoriolis.html

This website also shows that the drainage of sinks/toilets is affected more by their dimensions and how they're filled than by which hemisphere they're in.

RF

RF

Oh, and there's this as well: A593273

RF

i must admit i have been to a good few places abroad i have never looked to see what way the toilet flushes if it works it will do for me

normally get the key dump bags find the bar and if im in any fit state after find the pool

>normally get the key dump bags find the bar and if im in any fit state after find the pool<

...and then go to the toilet there?

i never get in that bad a state

Great quote at the top of http://www.ems.psu.edu/~fraser/Bad/BadCoriolis.html :

Be very, very careful what you put into that head,
because you will never, ever get it out.
Thomas Cardinal Wolsey (1471-1530)

Further down, I was interested to read that Michael Palin perpetuated the myth in his (BBC sponsored???) 'Pole-to-Pole' series... although one correspondent claims he debunked it as a scam, he says nothing of the sort on his own site: http://www.palinstravels.co.uk/book-1164

<>

In the ruins of what was once the Silverbeck Hotel, which straddled the Equator and offered punters the prospect of buying a beer in the Northern Hemisphere and drinking it in the Southern, a young African called Peter demonstrates the Coriolis effect by which energy in the Northern Hemisphere appears to be directed to the right, and in the Southern to the left. Peter drains a bowl of water in the North, and, by means of a floating stick, we observe that the water drains away in a clockwise direction. Then we (myself and a group of American tourists) wander with Peter, his stick and his plastic bucket into the Southern Hemisphere, where we observe that in exactly the same operation the stick turns anti-clockwise. On the Equator line itself, the stick doesn't turn at all.

</>

So if you're drunk in the southern hemisphere does the room spin the opposite way?

The above post has been nominated for an H2G2 Wilde Award



Voting open to all Researchers: F86994?thread=416544
The H2G2 Wilde Awards: A722053

Oh wow! Even Michael Palin doesn't know.

I know I don't quite get it yet.

Thanks six7s for that link:
http://www.ems.psu.edu/~fraser/Bad/BadCoriolis.html
which, if I understand it correctly, says that it ( the Coriolis effect ) is actually true for large weather systems but is merely a myth in sinks, tubs and toilets.

It says in part:
"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)".

Two points:

1. A hurricane is the lowest of low pressure systems and the linked site says that north and south of the equator the rotation is reversed.

2. I am also left wondering how it would be possible for the southern hemisphere of the "earth itself" to rotate in the opposite direction. It kinda leaves all the rest of the page in question.

What this question needs is a sailor who has been there and managed to get back.


~jwf~

>> 2. I am also left wondering how it would be possible for
>> the southern hemisphere of the "earth itself" to rotate in
>> the opposite direction.

I'm not entirely sure what you mean... but I have a hunch the following link might be of help

http://www.abc.net.au/science/louts/coriolis.htm









In Hertford, Hereford and Hampshire, hurricanes hardly hever happen

Down here, south of the border, they NEVER happen - we have cyclones instead

Apparently, neither hoccur hanywhere happroaching the hequator heither

http://www.smh.com.au/news/big-questions/if-a-hurricane-rotates-in-one-direction-and-a-cyclone-rotates-inthe-other-what-happens-if-they-cross-the-equator/2005/09/15/1126750065686.html

Like

>> how it would be possible for
>> the southern hemisphere of the "earth itself" to rotate in
>> the opposite direction.

> I'm not entirely sure what you mean...

That's my point exactly! I was quoting from the original linked page which says,

"...a hurricane spins counter-clockwise in the northern hemisphere, and clockwise in the southern hemisphere (as does the Earth, itself)"

which suggests that 'the earth itself' is rotating in two directions at once, with the top bit going counter-clockwise and the lower bits spinning clockwise, like some sort of planet-sized Rubic's Globe,

Probably not what the author intended, but it throws his whole page into doubt. So thanks for the later link.

And what about a compass needle? As it crosses the equator it must point east or west for a minute or two then flop toward the nearer magnetic pole.

I guess that's why nautical tradition has a ceremony in which the lowest ranking crewmember becomes Captain and the skipper has to perform the lowliest tasks on the day they cross the equatorial line, a moment of contraries and reversals.

peace
~jwf~

<< And what about a compass needle? As it crosses the equator it must point east or west for a minute or two then flop toward the nearer magnetic pole. >>

Bearing in mind the adage that a little knowledge is a dangerous thing, I won't try to answer your q. Instead, I'll point you towards


http://www.ngdc.noaa.gov/seg/geomag/faqgeom.shtml#q4
4. Where are the magnetic poles?

4a. What is a magnetic pole?

4b. Where are they?

4c. What is the magnetic equator?


http://www.ngdc.noaa.gov/seg/geomag/faqgeom.shtml#q5
5. How does a compass work?

5a. Does the compass needle point toward the magnetic pole?

5b. What happens to my compass at the magnetic pole?

5c. What happens to my compass in the southern hemisphere?

5d. How do I correct my compass bearing to true bearing?

5e. What influences the magnetic field measured by my compass?

A Wilde award, cool.

As I understand the Coriolis effect also works on the water in your bathtub, it is just that the flow of water can easily be affected by other factors. Dirt in the water, the form of the bathtub and such. Someone showed that water does indeed spin opposite ways when running out in the hemispheres, but only after having used very pure water and letting it stand for two weeks to release any gases first.

Thanks six7s for that link:
http://www.ems.psu.edu/~fraser/Bad/BadCoriolis.html



RF

>> As I understand the Coriolis effect also works on the water in your bathtub, it is just that the flow of water can easily be affected by other factors. Dirt in the water, the form of the bathtub and such. <<



RF

Yes and probably also ghosts.

Just pointing out that *I* posted the link, and also mentioned about the size of the receptacle being more important than the hemisphere...am I a ? Do people not see my posts?

RF

Whoah, my table just started moving. And what are those knocking sounds?