Coriolis Effect?

Question

Which of these winds is not influenced very much by the Coriolis Effect?

A. Jet Stream
B. Northeast Trades
C. Mid Latitude Westerlies
D. Sea Breeze

Answer 1

This is a good question. The answer is the sea breeze, because of its short time and space scales. In order for the Coriolis accelerations to act they need longer time and space scales as exemplified in a, b, and c. 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. Finally, from the eqn's above you can see that both the u and v components of the motion of a sea breeze are so small and the distance over which they travel are so small that the deflection is not measurable. If you could keep that motion up for great distances then you would see some deflection due to Coriolis accelerations.

Answer 2

Technically they are all effected by the Coriolis effect, but the best answer here is 'D', Sea breeze. Your question asks which is not influenced very much by the coriolis effect, and the key words in the question are "very much".

The Jet Stream, Northeast Trades and Mid Latitude Westerlies are all large scale global circulations, highly effected by the Coriolis effect.

The Sea Breeze is a local effect, and though the Coriolis effect will effect it somewhat, it will not be influenced very much.

Back in my Synopic Meteorology classes, we had to calculate the influence the coriolis effect had upon a baseball as an outfielder throws to home plate. The calculations show the coriolis effects that as well, albeit it is only a few millimeters.

Answer 3

The sea breeze is influenced by Coriolis and I am amazed that other meteorologists should say it isn't. It is one of the great experiments that science classes near the coast can do to look at Coriolis in real life.

Sea breezes start normal to the coast, that is at 90° to the coastline. During the day, the wind will veer in the northern hemisphere and back in the southern hemisphere due to Coriolis.

In Sydney, the sea breeze starts as a southeasterly around 9am. By 3pm it is a northeasterly. Coriolis is caused by the Earth's rotation which is one revolution per day. In six hours, a quarter of a day, you would expect to see a change of 90°, a quarter of a circle - and that is precisely what you do see.

It doesn't happen on the equator as Coriolis is zero there but in higher latitudes you can observe it. If you don't believe me, do the experiment yourself next time you are on the beach.

Answer 4

I would say to be influenced by the Coriolis Effect a wind must be on a global scale hundred or thouthands of kilometers. Therefore sea breeze.

Answer 5

D Sea Breeze

Answer 6

The seabreezes are small scale boundary layer features that are more driven by heat rising over land areas - being replaced by the marine layer. No coriolis effect involved, at least not on a scale that matters.

Answer 7

I'd have to say D. Sea Breeze.