The Coriolis effect.

[willie]

Calling you weather heads.
I've been doing my reading and cant get my head around how this works.

http://www.bom.gov.au/info/ftweather/page_14.shtml
The coriolis effect.

I convinced myself i understood it all, then after looking at this picture for a good hour i realised i was wrong.


Being in the southern hemisphere facing north, and the globe rotating clockwise for our point of view, If i were standing on X and throw a ball north, ofcourse, with the rotation of the globe, the ball would land to the west of the northern direction of that i threw, as showin in the picture in a anti clockwise rotation (reverse motion to the movement of the globe).
Though, if i was still at X and threw the ball towards the south pole, wouldn't the ball land towards the west to the direction south i threw it again?
Im confused as to why the line moves towards the east.

The site says - "Moving objects will appear to have been deflected to the left in the southern hemisphere and to the right in the northern hemisphere" - so does that mean it doesn't matter which direction your facing, either north or south?

Help needed as soon as possible, cheers.

[jose]

Dude, have you even tried throughing a ball that far? i dont think it possible, i think your bullshitting me.


but seriously interesting question, no answer, but you'd think it would go west both ways.

[2nd Reef]

The site says - "Moving objects will appear to have been deflected to the left in the southern hemisphere and to the right in the northern hemisphere" - so does that mean it doesn't matter which direction your facing, either north or south?

Help needed as soon as possible, cheers.

Doesn't matter if you're facing north, south, east or west.

The Coriolis Effect controls a lot of our weather phenomena. Think of something as simple as seabreezes - we get a NE'er on the east coast and in Perth they get a SE'er (the Fremantle Doctor). The breeze is caused by simple convection; air over the land heating and rising and the cooler air over the ocean rushing in to fill the void.

On the East Coast we have a (roughly) north-south running coast so therefore the wind should blow from east to west. But it doesn't. The Coriolis Effect kicks the wind to the left as it travels and we have a NE'er.

Jump over to Perth, which also has a north-south coast and instead of a westerly they have a SW'er.

[2nd Reef]

^^^Thats one way how I've tried to picture the CE but I've just looked at that graph for a while and I'm as confused as you Will!

Are you sure the red line is supposed to depict the path of a ball?

[wanto]

looks a little like the great circle theory, but that has nothing to do with coriolis, or does it?

"A Great Circle path is the shortest distance between two locations on a spherical object"

[Nick Carroll]

Can't see the difficulty here will...as long as you can get it that the planet is sort of ball-shaped, and the speed of the thrown object changes in relation to the circumference of the planet.

The Coriolis effect is made visible thanks to inertia -- the planet spins, but things (atmosphere, ocean, continents, magma etc etc) drag in the process. To take reef2's seabreeze image and sharpen it: a seabreeze in the southern hemisphere tends to bend so it blows from left to right looking seaward, and a seabreeze in the northern hemisphere tends to bend to blow right to left. Ie: Californian seabreezes blow from the northwest.

[Nick Carroll]

looks a little like the great circle theory, but that has nothing to do with coriolis, or does it?

Not directly -- only in the way that the Coriolis effect and the great circle theory both relate to the way the planet is shaped.

The great circle thing wouldn't even have come up had humans not obsessively tried to make flat-Earth maps, ie Mercator, that distort true planetary distances.

[chrisb]

The Coriolis effect is the reason that water spins out through a bathtub plughole in an anti-clockwise direction in the northern hemisphere and in a clockwise direction in the southern hemisphere.

Or is that the other way around

Has anyone ever had a bath while on the equator what happens when the water runs out

[wanto]

doing some stuff with mercator projection at work at the moment, have you ever seen a globe shaped computer screen? it's more a necessity then an obsession i think.

Has anyone ever had a bath while on the equator what happens when the water runs out

you towel off while admiring your adonis like features in the mirror?

[munch]

No idea how you visualise it the "other" way but the force is dependent on the bodies velocity in space so at X0 = 1200, at Xequator = 1670 and at Xpole=0, so;

X0-Xequator = -470 so a negative force
X0-Xpole = 1200 so a positive force

best I can do, hope it helps

[puurri]

Ask Shane Warne or Murali.

[bc]

The drawing is a bit misleading
-there's an optical illusion with the globe.

It can spin either way depending on whether you think you're above or below the rotation direction arrow.

It spins front towards the right yah?

[el gringo rattis]

try forget about north, south, east and west and just think about left and right till you get your head around it.....

in the northern hemisphere... displacement is to the right

in the southern hemisphere... displacement is to the left

intersting fact #1: the summer northerly winds blowing down our east coast shift a whole stack of warm surface waters southward.... but the effects of coriolis displace this surface water to the left (southern hemisphere) and therefore to the east and offshore....... this results in water from a depth moving in to replace the surface water (upwelling) and thats why you can get those crazy cold patches and days when the water is bloody freezing in the middle of summer.

[Beanpole]

Yet another example of why I should have listened in maths class instead of drawing waves in my exercise book

[doowdle]

el gringo is right, Its not east west, its left right.

The key to the coiolis effect is the changing diameter of the earth as you move north and south. Due to this difference, things move faster due to the planets rotation nearer the equator than they do nearer the poles - to zero of course, at the poles you just spin on the spot. do you get dizzy? not sure. speed due to earths spin at the equator iss around 1600km/h eastwards.

If you move a parcel of air or whatever north towards the equator, it will be moving slower than the air around it, (due to NC's inertia it won't instantly accelerate to the new latitudes speed) causing it to veer off to the left.

If you move a parcel of air to the south, away from the equator, it will be moving faster than the surrounding air so will veer to the left.

That was the easy bit, why veer to the left when moving east or west?

if you move the parcel eastwards, you increase its rotational speed , which increases the centrifugal force acting on it. which throws the parcel outwards (like water in a bucket tries to when you spin round) the parcel takes the easiest route to increase its radius of curvature - it moves to where the planets diameter is greater - yep, it turns left again. If you push the parcel west, its centrifugal force decreaces, it wants to spin round a smaller radius so it moves south, left again.

Thats why winds caused by low pressures and water caused by plug holes spin, the parcels try and rush towards the center and corilolis makes them turn constantly to the left.

[Freshie Boy]

its basically an object moves at a different speed depending on what latitude it is located at.

ie if you were in the Arctic circle, there is less distance to travel around the earth to make a full rotation, therefore the movement is faster, compared to an object stationed on the equator, being the widest part of the earth, it would take a little bit longer to complete a full rotation around the earth back to the point it was stationed at.

[MikeeR]

On a basic level I've always found the Coriolis force reasonably straight forward to understand - in that it forces moving bodies to the left in the southern hemisphere, to the right in the north. It's such a subtle but relentless force that can be seen from the scale of water down the drain to deflecting wind and water over huge distances.

What I find amazing is the level complexity in some of the results. For example it's effect on ocean currents and cold water upwellings that we feel here on the east coast. Check these:
http://www.swellnet.com.au/analysis/Col ... 290805.php
http://sparce.evac.ou.edu:80/q_and_a/oc ... ations.htm

[willie]

If you move a parcel of air or whatever north towards the equator, it will be moving slower than the air around it, (due to NC's inertia it won't instantly accelerate to the new latitudes speed) causing it to veer off to the left.

If you move a parcel of air to the south, away from the equator, it will be moving faster than the surrounding air so will veer to the left.

I asked the lecturer today (this presentation is due in 3 hours ) and he stated what doowdle has said. It drags to the left in the southern hemisphere when moving north, as the equator region rotates at a faster rate.
Moving south, the rotational speed at the pole is slower, though still drags to the left of its original destination.
Im not going to attempt to go into much depth on the subject, i think even the lecturer was a bit puzzled when i asked him.
i think in the presention ill just state
"southern hemisphere... drags left.
North... drags right..
DONE!"


*oh and ill also pray there are no questions *