Date: Sat, 23 Mar 1996 06:22:15 -0600
To: noon@lynx.ed.uiuc.edu
From: "Judith Bennett" <elanora@zip.com.au> (by way of Jim Levin)
Subject: Differences between the Northern & Southern Hemisphere: another
 extension to the Noon Project

Dear Jim,

>Generally you would be right, that the shadow length in the northern
>hemisphere would be different from that you get down there.  However, since
>this is near the first day of spring, the sun is right over the equator,
>and so shadows at equal latitudes will have equal lengths (but different
>directions - your shortest shadow pointed south, right?

Thanks and yes, who ever heard of a shadow lying to the North!
(Just joking - I lived in Massachusetts for 2 yrs at one stage)

North facing rooms in Sydney get fairly hot in Summer.
Most of our storms come in from the South.

The water swirls around when going down our plugholes in the opposite 
direction to the way yours does.
Vines that twist around the trunks of trees grow around the tree in 
the opposite direction to yours.

Or so I believe - maybe your kids could check me out somehow.

Melbournians from Victoria try to holiday to the North in Winter to 
get warm!  = you lot racing off South to Florida.

Thanks for your information,
Cheers,
Judith
------

>From Jim: I wrote to Judith and got her permission to send this on to
the rest of you.  Here's her response - any of you want to take up her challenge
of having your students observe the direction that water swirls down a
drain/plughole?  How about testing out other differences, like the
directions vines go around trees?  Are there other such differences?
Can they be reliably observed by your students?

>Comments: Authenticated sender is <elanora@mail.zip.com.au>
>From: "Judith Bennett" <elanora@zip.com.au>
>Organization: Elanora Heights Public School
>To: Jim Levin <jim-levin@uiuc.edu>
>Date: Sat, 23 Mar 1996 15:19:40 +0000
>Subject: Re: Sydney - sunny again!
>
>Dear Jim,
>
>> Many thanks Judith.  Do you mind if I forward your message on to the whole
>> noon group?  I think they'd be interested in your observations of
>> differences between the hemispheres.
>
>Please do because I have just written of to Linda in Atlanta who is 
>at latitude 33:39 and got a length of 66 (we are at 33:43 and got 
>65cm) and asked her to get her kids to watch the whirlpool as they 
>pull the plug out of the bath and see if it is clockwise or 
>anticlockwise.
>
>I really want to know now.  I know which way it goes here and I want 
>to know if my information was correct about which way your bathwater 
>goes.  I suggested they put a little bit of plastic in the water and 
>watch which way it spins.
>
>Thanks,
>Judith
>
>Have you ever seen that list of suggestions about "How to make an 
>impact when you meet someone at a party"?
>One suggestion is, instead of saying "Where do you come from?" or 
>something equally inane, you ask "And which end of the bath do you 
>sit?"
>Well I am providing a new impact question "Now which way does your 
>bathwater go down the plughole?"  If you are not hustled out the door 
>immediately, you may get to make interesting friends.



Date: Sun, 24 Mar 1996 07:27:27 +1000
From: Rex Boggs <rex@cq-pan.cqu.edu.au>
Organization: Glenmore High School
To: noon@lynx.ed.uiuc.edu
Subject: Re: Differences between the Northern & Southern Hemisphere

Hi all

> The water swirls around when going down our plugholes in the opposite
> direction to the way yours does.
> Vines that twist around the trunks of trees grow around the tree in
> the opposite direction to yours.

> Here's her response - any of you want to take up her challenge
> of having your students observe the direction that water swirls down a
> drain/plughole?  How about testing out other differences, like the
> directions vines go around trees?  Are there other such differences?
> Can they be reliably observed by your students?

The fact that water swirls down the plughole in the opposite direction in 
the Southern hemisphere is a myth.   In theory, it could, due to the Coriolis 
effect.  (This is the effect one sees if they are standing at the centre of a 
merry-go-round and tosses a ball to the circumference - it appears to travel 
in a curved path.  What actually happens is the ball goes straight but the 
motion of the observer makes the path look curved.)   But the force is very 
small, and other variables come into play that have more effect - the motion 
of actually removing the plug being the most important one, I suspect, but 
also the shape of the bowl, slight imperfections in its construction and so 
on.

But the vines are an entirely different matter!  As they grow around a pole, 
they follow the sun, from east to west.  The sun will pass to the north of 
the pole in the southern hemisphere and to the south in the northern 
hemisphere.  This difference would certainly be worth testing.  If my theory 
is correct, vines should grow in a counter-clockwise direction in the 
southern hemisphere and in a clockwise direction in the northern hemisphere.
As viewed from above.