What causes the Coriolis Effect ?

Answer 1

Coriolis force, named after the French scientist who first described it in 1835, affects all objects moving freely across the face of the earth. Essentially, things such as ocean currents and airplane flight paths, which would otherwise follow a straight line, end up tracing a curved path due to the earths rotation.

The best example is on a spinning merry go round. If you throw a ball it looks like the ball curves from the riders perspective however if you look at it from an outsiders standpoint it goes straight.

Answer 2

Let's start with a given object located at the equator, and stationary relative to the surface of the earth. At this location, it is going around the planet, about 40000 km in circumference, in 24 hours, or at a speed of 1670 km/hour. Now, we move this object off the equator (either north or south, it does not matter) to an area where going around the world, in a path parallel to the equator, is less, say we move to 30 degree. At that location, going around the planet is about 34600 km, and to go around still takes 24 hours, so the speed should be 1450 km/hr. But what happens to the extra 220 km/hour then? (An extreme case of this is moving from the equator all the way to the pole, where the tangential velocity has to be zero, leaving a 1670 km/hr -- that is about 460 m per second! -- unbalanced). Because of inertia, any object thus moving away from the equator will tend to overtake the earth's rotation. This, in turn, creates eddies and currents in the atmosphere, and that is where all those cyclone start, some of them can turn into hurricanes under the right conditions.

Answer 3

Excellent question. But permit me to answer it in the correct mathematical manner. When you study the "equations of motion" on a rotating earth you will find there to be four components of the coriolis force (or more properly acceleration since we use forces per unit mass). I will only given you two of these components. Due to the northward motion of the air there is an eastward component of the coriolis force given by 2 O v sin phi where O, Greek symbol is omega, is the angular rate of motion of the earth, v is the northward component of motion and phi is the latitude which you are considering. Due to the eastward motion of the air there is a northward component of the coriolis force given by -2O u sin phi, where u is the eastward component of motion and the other symbols remain the same. Since this component is negative it acts in the southward direction. The Coriolis forces involve only those components of the total motion measured relative to a rotating frame, which lie in a plane perpendicular to the axis of rotation (equatorial plane). They are directed to the right of these velocity components in an equatorial plane with magnitude = 2 Omega V where V is the part of the velocity which lies in an equatorial plane as I have shown above. Finally, because the Coriolis acceleration is always perpendicular to the velocity of the air it can never change the speed of a parcel of air, only its direction of motion. This is the reason it is sometimes referred to as as deflecting force. You can experience this if you have one of those rotating platforms on a school playground near you. If you stand on one side and a friend stands on the other and while the platform is rotating you try to toss a ball to your friend you will observe the Coriolis acceleration. The ball will curve to your right. Finally, to answer your question specifically. Because the sin phi term is positive in the northern hemisphere and negative in the southern hemisphere the Coriolis accelerations are in opposite directions in the two hemispheres. These Coriolis terms simply fall out in the mathematics when you work with the equations of motion, but can be explained by the rotation of a coordinate system on a sphere.

Answer 4

Simple answer:
Earth rotates underneath a moving parcel of air.

From Earth, it looks like the parecel is deflected. From a fixed point in space, the parcel moves straight while the Earth rotates under it.

Answer 5

The earth's atmosphere's rotation lags slightly behind the rotation of the surface tending to make the northern hemisphere's weather patterns move from east to west and the southern hemisphere's weather patterns to move west to east.

Answer 6

the rotation of the Earth

Answer 7

as above