Antipodean Plug-Holes

[Oliver_...@amdahl.com]

Hello -
Can somebody please, once and for all, put my mind to rest over the subject of
water spiralling the opposite way in each hemishere. I have recently conducted
some experiments with the following conclusions: Water spirals clockwise in
Australia and anti-clockwise in my bathroom in London. Is this due to earth
rotation or am I imagining it or is it just chance. Come on eggheads, help a
thicky out!
Oliver

[Peter Ceresole]

In article <NEWTNews.861203487.825.ozt20@ozt20-pc1>,
Oliver_...@amdahl.com wrote:

>Can somebody please, once and for all, put my mind to rest over the subject of
>water spiralling the opposite way in each hemishere.

Okay.

It happens. The effect is *extremely* small, and in everyday life it will
be totally swamped by other effects, like which tap you used to fill the
basin and exactly in what direction the jet was pointed. The residual
effects of that, plus any disturbance you create when you pull out the
plug, will overwhelm the effect due to coriolis force. And clearly, your
basins in Oz and in London are differently arranged.

However, using large tanks of water and rigorous conditions of careful
filling, rigorously excluding draughts that might impinge on the surface or
create a temperature gradient (hence convection) in the vessel and allowing
the water to stand for days before carefully opening the drain, I believe
that the effect has been observed experimentally.

It's rather more easily observed in ocean currents and weather systems,
which are anyway more fun than bath tubs.

Mind at rest yet?

--
Peter

[The Bad Astronomer]

Oliver_...@amdahl.com wrote:

: Hello -
: Can somebody please, once and for all, put my mind to rest over

: the subject of water spiralling the opposite way in each

: hemishere. I have recently conducted some experiments with

: the following conclusions: Water spirals clockwise in
: Australia and anti-clockwise in my bathroom in London. Is

: this due to earth otation or am I imagining it or is it

: just chance. Come on eggheads, help a
: thicky out!
: Oliver

Hi Oliver. It's just chance. There is minimal correlation
between drain direction and hemisphere. I suggest you
take a look at my Bad Astronomy pages (URL in the .sig
below) and look at the "water draining" link. It has links
to other sites that explain this urban legend very well!

* * * * * * * * The Bad Astronomer * * * * * * * *

Phil Plait bada...@patriot.net
Bad Astronomy Web Page: http://patriot.net/~badastro/bad.html