The Coriolis effect ?

Question

Why does The Coriolis effect deflects objects moving along the surface of the Earth to the right in the Northern hemisphere and to the left in the Southern hemisphere?
Please Explain it with a suitable experiment

Answer 1

The Coriolis effect works due to the fact that the earth (different from what is commonly taught in school) is NOT an inertial frame, because of the rotation the earth has; inertial frames are created when an object is moving at constant velocity, and the earth has no lineal movement, the tangential velocity (as vector) is ever changing although it's magnitude is always kept (like in any other rotating frame), then this velocity is not constant it has an acceleration (known as centripetal acceleration) and as a result pseudo forces (like Coriolis force) are created (like when you're in a car and you accelerate, this is called the inertial force).
The Coriolis force term can be obtained theoretically (If you want to profoundest I recommend you the book named "Classical dynamics of particles and systems" by Stephen T. Thornton & Jerry B. Marion), and, as seen in wikipedia, this force depends on the velocity mainly (as vector) and the angular velocity (whose cross product changes sign depending on you're on the Northern hemisphere or the Southern hemisphere, and it's cero on the Ecuador, so that this force is equal in magnitude but different in direction in the Northern and the Southern hemispheres at the Tropic of Cancer and the Tropic of Capricorn, for example)
I did an experiment about the Coriolis effect in my mechanics lab. You can use or build an scaled Foucault pendulum (because an usual Foucault pendulum is just impractical, by the time you need for the effect to be noted and by the size predicted by some theory you need the pendulum to be) and observe how are felt the fictitious forces. As you may see in the theory given by some books, online articles or even the wikipedia for the effect to be seen (precession of the pendulum) it is needed some parameters to have certain values (Rossby number) and by creating and small rotating frame with a relative high angular velocity (for example 34 rpm) you can see, according to the rotating frame, the precession that shows the Coriolis effect.

Edited:

If you know spanish you can get more detailed information on the Coriolis effect and non intertial frames in http://www.sc.ehu.es/sbweb/fisica/cinematica/coriolis/coriolis.htm

Otherwise, you can even use a translator, this site is worth and for many spanish speaking students in physics from high school to university it's been a good resource...

Answer 2

This is a basic explanation:

The equator is furthest from the axis of rotation of the earth, so objects nearer the equator must be moving faster than objects more northward, since the whole system moves at the same angular velocity. When a hurricane is forming, the center is low pressure. The air outside it will naturally go towards it. But air has different levels of east-west velocity depending on where it started from, on how near it was to the equator. So air starting from the equator will head to the east as it approaches the low pressure center, and that from the north will lag behind the air it approaches, so will move to the west. So we now have forces that can cause the whole system to rotate. I assume once it gets to rotating it just keeps its momentum. In the northern hemisphere, this will make a storm rotate counterclockwise if viewed from above, and those in southern hemisphere will rotate clockwise.

This force is called the Coriolis force.

When the military launches projectiles from long-range guns, and the direction is near north or south, this must be taken into account. I think this happened in the civil war, that cannons would miss because of this.

Answer 3

Imagine squashing the earth flat so that its a thin disk. The outer edge will be moving faster than the very centre where there will be almost no movement at all. So an object which moves from the outer edge towards the centre will appear to move to the right as the disk is rotating anticlockwise. In the Southern hemisphere rotation appears clockwise
To experience this, stand on the outer edge of a moving merry-go-round and roll a ball slowly towards the centre and watch what happens. Try the test with the merry-go-round rotating the other way.

Answer 4

"The Coriolis effect caused by the rotation of the Earth is responsible for the precession of a Foucault pendulum and for the direction of rotation of cyclones. In general, the effect deflects objects moving along the surface of the Earth to the right in the Northern hemisphere and to the left in the Southern hemisphere. As a consequence, winds around the center of a cyclone rotate counterclockwise on the northern hemisphere and clockwise on the southern hemisphere. However, contrary to popular belief, the Coriolis effect is not a determining factor in the rotation of water in toilets or bathtubs (see the Draining bathtubs/toilets section below)"

This, and more, on the Coriolis effect is at Wikipedia, the free, online encyclopedia:
http://en.wikipedia.org/wiki/Coriolis_effect

The classic experiment to prove the Coriolis effect is the
Foucault pendulum. In Wikipedia at:
http://en.wikipedia.org/wiki/Foucault_pendulum

Hope this helps!

Answer 5

Coriolis effect comes about due to rotation of Earth. It is good to bear in mind that the force due to Coriolis is indeed very small, IE due to one rotation of Earth per day. It will certainly effect intercontinental ballistic missiles. hurricanes, tempests and the like. It is important to remove a misconception that water draining in a sink in a clockwise or anti-clockwise is due to Coriolis. It is not. It primarily depends on how water was ejected out of the outlet faucet. It depends on the geometry of construction of sink not on Coriolis. The direction of Coriolis effect follows the direction of Earth's rotation anti-clockwise in Northern Hemisphere and opposite to that in Southern Hemisphere.

Answer 6

The answers given so far remind me of newtons concept of gravity. He describes what it does, not does not give the reason for the force itself - it is c2 = E/m.

The Coriolis force DOES exist due to the spin of our planet, but the reason for the existence of this force is due to the energy of rotation increasing as one moves from either pole toward the plane of the equator. Were you to divide a styrofoam sphere in half, and mark the face of each with arrows to indicate the direction of mass rotation, you would find that one hemisphere cannot directly take the place of the other - the arrows indicate mass movement in opposite directions were one hemisphere to directly take the place of the other (hold the hemispheres so that the face of each is seen at the same time). It is much like a person looking in a mirror and pointing with their right hand to their left side. The image in the mirror points in the opposite direction.

As the force of hemisphere rotation meets at the equator, in order to move in the same direction, the force moves opposite each other. This is evidenced in the mass of our planet in that there is a 25' rise in mass in the southern hemisphere at the equator that does not exist in the northern one (found by Vanguard I). This rise in mass is due to the resistance that the mass rotation offers the hemispherical energy of rotation. In the northern hemisphere mass and energy of rotation move in the same direction, so the rise in mass does not occur at the equator.

Lastly, this same form of energy forms our planet's magnetic field. This is seen by this force causing a shearing action through the planet of earth's equator. When there is a strong shearing action through a plasma, an electric field is formed, then at right angles a magnetic field develops - which is the reason that we have directly opposing magnetic fields.

Answer 7

The simpsons Episode "Bart Verses Australia" explains the Coriolis effect very well!
Now only if I could acutally get into the Australian Embassy to see if the Toilet flow goes right (with the assistance of pumps!)

Answer 8

Same reason water goes down the sink one direction in the northern and the other in the southern - gravity and planet rotation; the earths gravitation field extends deep into space, much farther on the side of the sun than the opposite back side, if mars is passing on the back of it the earth, on the suns side the field extends almost the same distance towards the sun as the distance from earth to mars. It is about one tenth the distance in the mars direction. Use Newtons gravitational laws for planets for the easiest ways to understand this concept

Answer 9

The easiest way to demonstrate this is to go to the playground with your friend and get on the merry-go-round. Get the thing spinning with you and your friend on opposite ends holding a bunch of tennis balls. Start throwing the tennis balls at each other and see where the balls go.