Talk:Coriolis force/archive3

message: Could someone write about how Coriolis effect can be used to produce artificial gravity on rotating space stations and how it works there? Kaol 3 July 2005 20:23 (UTC)
:Actually, creating artificial gravity by constructing a wheelshaped space-station, and have that space-station rotate is not an option.<BR>
:I have not performed the calculation myself but I found a source that mentioned that if you have a space wheel with radius of 100 meter then the rotation rate required to get an artificial gravity is one rotation every 20 seconds, and that would result in Coriolis forces that would be almost 4000 times stronger than on the Earth. Machinery with moving or rotating parts, like centrifuges and washing machines might break down. It whould be unconformatable for the crew, for in every motion they make they would experience unsettling coriolis effects.
:--Cleon Teunissen | Talk 3 July 2005 22:15 (UTC)
The coriolis effect is just an effect.  It cannot be used to produce artificial gravity.  And the effect is not relevant directly to the phenomemon of artificial gravity.  Spinning the space station creates centripetral forces the same as those which keeps the water in the rotated bucket or the motorcycle against the wall of death.  Inside a rotating space station one could think that gravity was pressing you to the wall.  "Artificial gravity" so created is, however, not gravity.  Paul Beardsell 11:59, 1 August 2005 (UTC)
thread_title:  Rotating space stations 

message: There is coriolis dynamics, but there is no such thing as an irreduceble 'Coriolis force'. In that specific sense there is no Coriolis force.
In physics it is quite common to refer to something special with the word 'effect'. Example: the Casimir effect. The Casimir effect is a manifestation of general quantum physics principles, so there is a Casimir effect, but there is no standalone Casimir force, it is a particular behavior that is elicited in that particular configuration. Occasionally the expression 'Casimir force' is used. Again, that does not mean that it is assumed that there is an irreduceble Casimir force, this "Casimir force" is an epiphenomenon, it can and should be accounted for in terms of fundamental principles.
The Casimir effect analogy, featuring ships in a strong swell, is striking. There is an effect, but not a single force. 
=== There is no coriolis force ===
The coriolis effect gets to have a name of its own because it occurs in certain recognizable circumstances. Like the Casimir effect, the Coriolis effect is an epiphenomenon, it can and should be accounted for in terms of fundamental principles. --Cleon Teunissen | Talk 7 July 2005 08:58 (UTC)
:Unlike physics, there are few absolute limits in language. It can be understood that the "Coriolis force" refers to an apparent force resulting from the Coriolis effect. If this wasn't the case, the term wouldn't pop up so often, I think. DavidH 06:06, July 29, 2005 (UTC)
::Yes, of course the expression coriolis force is useful physics shorthand,  and I support using it as such. Likewise, the expression 'centrifugal force' is useful physics shorthand, as in the name centrifugal governor. Unfortunately the expressions centrifugal force and coriolis force are often taken als literal. --Cleon Teunissen | Talk 07:59, 29 July 2005 (UTC)
thread_title:  Why the 'coriolis effect' is called 'coriolis effect' 

message: The coriolis effect gets to have a name of its own because it occurs in certain recognizable circumstances. Like the Casimir effect, the Coriolis effect is an epiphenomenon, it can and should be accounted for in terms of fundamental principles. --Cleon Teunissen | Talk 7 July 2005 08:58 (UTC)
:Unlike physics, there are few absolute limits in language. It can be understood that the "Coriolis force" refers to an apparent force resulting from the Coriolis effect. If this wasn't the case, the term wouldn't pop up so often, I think. DavidH 06:06, July 29, 2005 (UTC)
::Yes, of course the expression coriolis force is useful physics shorthand,  and I support using it as such. Likewise, the expression 'centrifugal force' is useful physics shorthand, as in the name centrifugal governor. Unfortunately the expressions centrifugal force and coriolis force are often taken als literal. --Cleon Teunissen | Talk 07:59, 29 July 2005 (UTC)
thread_title:  There is no coriolis force 

message: The example most often given in presenting the Physics of the Coriolis effect is the figure skater, spinning at a dazzling rate. A google search with the search terms "coriolis" and "figure skater" finds lots of them.
As I described earlier, in the 'two incarnations' posting, there are actually two phenomena, that only have the theme of rotation in common, that are both referred to as "the coriolis effect". 
I decided to deal exclusively with the version of 'the coriolis effet' that needs to be taken into account in engineering and meteorology. That is where the action is. --Cleon Teunissen | Talk 18:19, 10 July 2005 (UTC)
thread_title:  The figure skater, the ambassador of the coriolis effect. 

message: Everything I've read about Coriolis effect points out that small 'systems' like sink drains and toilets aren't affected, and that the direction of water flow has more to do with the shape of the basin and whatnot. If this is truly the case, then are we to assume that all toilets made in the United States are purposely shaped so the water drains counter-clockwise, while all Australian-made toilets are designed to drain clockwise? It's a conspiracy, I tells ya! --Birdhombre 17:41, 14 July 2005 (UTC)
thread_title:  Drains and toilets 

message: The edits by 158.147.141.49 contain a simplification that I think should not be made. I use extensive simplification myself, it is a judgement call wich ones to make.<BR>
158.147.141.49 wrote:
:The air flow that is initially moving in a direction from South to North is moving closer to the Earth's axis of rotation. The Eastward linear velocity of a point on Earth close to its axis of rotation is less than that of a point close to the equator. As the air flows towards the axis of rotation, its Eastward linear velocity remains constant as the Eastward linear velocity of the point of Earth is it above becomes less and less. This causes the angular velocity of the air flow to increase, and rather than continuing on a straight path towards the center of low pressure, the flow will curve its right, or East as shown in the images to the right.
158.147.141.49 is here invoking conservation of linear velocity. However, that underestimates the coriolis effect. <BR>
The first meteorologist to consider the influence of the fact that the Earth is rotating was Hadley, in 1735. Hadley only considered conservation of linear velocity, and thus his theoretical prediction of the strength of the trade winds came out half as strong as in reality, causing doubts about the validity of meteorological theories.
There is in fact a 'double action' which can be seen in the first animation: the weight only moves closer to the axis of rotation if a force is exerted, and that force increases the rotational energy. This is why there is a factor 2 in the formula: :\vec{F}_C=-2m \vec{\omega} \times  \vec{v} . It is that double action that is so characteristic of the coriolis effect, and it should be included.
158.147.141.49 as also added:
:Cyclones cannot form on, and rarely travel near, the equator because there is little to no Coriolis effect present to sustain them.
That is an important addition. I hadn't written that up yet. --Cleon Teunissen | Talk 20:39, 19 July 2005 (UTC)
thread_title:  The edits by 158.147.141.49 

message: I've been avoiding this article for a while, because I disagree with CT over much of the content and structure. But if its up for PR/FA I shall comment:
* Almost all the edits are by CT, and almost all the sections are unsourced, except by the general refs at the end. I find this unsatisfactory.
* In particular the section Imagine a planet with the exact shape of the Earth, but non-rotating (this is in fact physically impossible, the force of gravity contracts a non-rotating celestial body to a near-perfect sphere.) Imagine the planet has no liquid on the surface and the surface is smooth. Imagine you are at the north pole, and you give a frictionless puck a large velocity away from the pole. The puck would soon return to the pole, because in moving away from the pole it is moving uphill. seems dodgy (the corilois force is proportional to the speed, which is not true in this case. So... where did this text come from? Its unsourced. Is it just CTs own example, or what?
* Figureskating is almost always presented as simple conservation of angular momentum.
* Moving the formula down is dubious. I would like to see it right at the start.
* I don't at all understand In the case of the coriolis effects in the atmosphere the cyclonic flow arises because the direction of flow of air masses is strongly affected by the force of gravity. For example: air flowing from East to West is deflected because it is pulled towards the Earth's axis of rotation by the force of gravity.. AFAIK gravity plays no role at all. But this statement, like all others, is unsourced.
William M. Connolley 20:42:24, 2005-07-28 (UTC).
William I want to reply to two of your more minor points. 
*The fact that a spinning iceskater is usually explained in terms of conservation of angular momentum is neither hear not there. The only important point is whether it is valid to explain it in terms of conservation of energy as done here.
* You state that "moving the formula down is dubious" but you don't say why. How can anyone adress that concern? Theresa Knott  (a tenth stroke) 09:23, 30 July 2005 (UTC)
thread_title:  PR comments 

message: About sources: if for example an article states that the Earth rotates, and that it is orbiting the Sun, then that particular statement would not rquire specific reference; it is general knowledge, plain for all to see.
 
It is common practice in physics texts to use thought experiment with a clear outcome. In for example the article about planetary orbitthe image :Image:OrbitingCannonBalls.png is shown.  The function of that image is to make the reader see the logic, so that the reader does not have to take the article's word for it, the reader can verify for himself that it is correct, by thinking it through.
*If a planet would be perfectly spherical, and it would also rotate, then all the water would flow to the equator, for on the spherical planet the proper centripetal force on the water would not be provided by the planet's gravity. 
*Conversely, if a planet would be a ellipsiod, but non-rotating, then all the water would flow to the poles, for the poles would then be point of lowest gravitational potential.
Of course, both situations are strictly hypothetical, for celestial bodies that are rotating around their own center of mass are always in dynamic equilibrium, ellipsoid in shape, such that the water and air is equally thick all over the planet. 
However, the ellipsiod shape of the Earth creates an arena for physics taking place that is in simplified form modeled by a turntable with a parabolic surface. An object on a flat turntable would simply fly off. That is centrifugal effect, with just a smithering of Coriolis effect. The parabolic turntable sets up an environment where the centrifugal effect is cancelled, so that what remains is all Coriolis effect.<BR>
These are not ex cathedra statements, all of this is pretty elementary physics, readily verified by the reader.<BR>
I shall see if I can find appropriate quotes in the work of James F. Price, for reference.
--Cleon Teunissen | Talk 05:59, 29 July 2005 (UTC)
thread_title: Sources

message: One of the themes of the article is that the expression coriolis effect is to be understood as analogous to expressions like 'Doppler effect' and 'Casimir effect'. There is a Doppler effect, there is no "Doppler force", there is a Casimir effect, there is no "Casimir force".
A belief that there actually is a "Coriois force" is a metaphysical belief. --Cleon Teunissen | Talk 05:59, 29 July 2005 (UTC)
thread_title: The expression Coriolis effect is like the expression Doppler effect

message: About the ice skater and conservation of angular momentum.
Of course, conservation of ancgular momentum does apply in the case of the  ice skater, but conservation of momentum is relatively unsuited for explaining the dynamics of a situation.
For example, when a cannon is fired the projectile is hurled away and the barrel recoils, as there is conservation of momentum. It sounds rather odd to say 'the projectile flies away because the barrel recoils'. That is rather unsatisfactory. A dynamic explanation focuses on what happens to the energy: the gunpowder explodes, chemical potential is converted to heat, expanding gases accelerate the projectile through the barrel. The general practice in physics is to look to the energy and to the forces. Energy is more associated with causality, because energy is associated with how processes develop over time, while momentum is more associated with symmetry of space. 
In the Coriolis effect there is conversion of energy from one form to another. Potential-kinetic, kinetic-potential The general physics approach to understanding a phenomenon is to keep track of the energy conversions. --Cleon Teunissen | Talk 05:59, 29 July 2005 (UTC)
thread_title: The ice skater and keeping track of the causal chain

message: In the article it is stated: 
:[...]air flowing from East to West is deflected because it is pulled towards the Earth's axis of rotation by the force of gravity.
William M Connolley has written:<BR>
:AFAIK gravity plays no role at all. 
You are misinformed, everything that is resting on the surface of the Earths is affected by gravity the way that is modeled in the parabolic turntable demonstrations.<BR>
I shall see if I can find appropriate quotes in the work of James F. Price., for reference. --Cleon Teunissen | Talk 05:59, 29 July 2005 (UTC)
thread_title: The influence of gravity, redirected by the slope

message: In the bath tub example it is said that the system is small is the reason the coriolis effect is not seen.  In the ballistics example the reason given for seeing the effect is that the distance is large.  No, it is only partly dimension which is at issue:  The other is time.  If a very deep bath tub is drained through a small hole over a period of days the coriolis effect will make itself measurable.  Similarly with a missile:  Don't forget the time!  The faster the missile the less the correction required.  Paul Beardsell 09:21, 30 July 2005 (UTC)
thread_title:  Don't forget time! 

message: The goal of the following text is the question: if you have a planet that is non-rotating and that like Earth is an oblate spheroid, and you give a ball a push away from one of the poles, what will happen then, and what is the cause of what happens then. Click here to go straight to that part.
I'm putting it into a larger perspective, showing how it fits in with models of the coriolis effect in meteorology, giving the story in one go rather than drawn-out, fragmented discussion.
One of the problems is Babylonian confusion about the expression 'Coriolis effect'. There are two different phenomena, that are both called Coriolis effect. 
=== Definition ===
First a definition, I define as 'mechanical Coriolis effect' the effect that was described in the 1835 paper by Gaspard Gustave Coriolis. It is illustrated in the animation.<BR>
This can also be descibed as Angular Acceleration Accompanying Contraction, and of course its inverse: Angular Deceleration Accompanying Relaxation.
Berkeley Physics Course, second edition, Mechanics, Chapter 6, page 193, discusses Angular Acceleration Accompanying Contraction, and shows that when there is rotation then contraction of the rotational motion requires doing work. <BR>
There is conservation of angular momentum, but there is not conservation of kinetic energy, work must be done, by a surplus of centripetal force. The explanation in terms of conservation of angular momentum is less suitable in the field of meteorology, the explanation in terms of energy conversion fits the requirements better, this has been shown by the meteorologist Anders Persson. I shall return to that in a future posting to this Talk page, first the main issues should be adressed.
=== Motion of a Ball in a Bowl ===
To prepare for discussing motion on a an oblate spheroid, I will discuss motion of a dry ice puck on a parabolical surface such as is used in the 
Massachusetts Institute for Technology fluid dynamics education
==== Non-rotating motion ====
The animation shows a harmonic oscillation (simplified representation, neglecting factors that would slowly build up deviation from simple harmonic oscillation.) <BR> 
The animation represents the puck going back and forth across the parabolic surface. The restoring force is proportional to the distance to the center of oscillation. The restoring force is doing work all the time. It is doing work when it is accelerating the puck to the center of oscillation, it is doing negative work (conversion of kinetic energy to gravitational potential energy) when the puck is moving away from the center of oscillation.<BR>
The restoring force is the force of gravity, redirected by the slope of the parabolical surface.<BR>
There is of course no Coriolis force involved.
==== Orbiting motion ====
The animation shows an elliptical orbit of the puck on the parabolical surface. (The parabolical turntable is rotating now to reduce friction between the puck and the surface). In a real world demonstration the elliptical orbit of the puck on the rotating turntable would, because of friction, slowly be rounded into a concentric circular orbit, just as winds are slowed down by friction over the course of weeks.
Reference: General planetary spreadsheet Excel spreadsheet for calculating orbital dynamics By Micheal Fowler. Department of Physics, University of Virginia.<BR>
This spreadsheet allows a wide range of force laws, including a force that is proportional to the distance to the center of attraction, as well as the more familiar inverse square law. <BR> direct link to the Excel orbital motion spreadsheet  Try it! Start the proportional force simulation, and see how a difference in starting velocity leads to a difference in eccentricity of the elliptical orbit. It's fun!
An elliptical orbit can be seen as a superposition of two perpendicular harmonic oscillations. The restoring force in the case of the parabolic turntable is the force of gravity, redirected by the slope of the parabolical surface. In all there are two forces here: the force of gravity, and the force exerted by the surface perpendicular to the surface. The resultant force can be decomposed in a vertical component and a (horizontal) centripetal force, maintaining the elliptical orbit of the dry ice puck.
There is no Coriolis force involved.<BR>
I repeat, because exactly this is misunderstood by William M Connolley, in the animation 'Elliptical orbit' there is no Coriolis force involved
The motion that occurs can be accounted for by assessing the effects of the centripetal force, no further assumption is needed.
The changes in the angular velocity of the puck are related to the mechanical coriolis effect: Angular Acceleration Accompanying Contraction, and its inverse: Angular Deceleration Acompanying Relaxation. 
===Motion of a Ball on an oblate Spheroid ===
==== Non-rotating oblate spheroid ====
On the images the brown ellipse represent a planet, a bit rust-coloured, no water on it, an oblate spheroid in shape and non-rotating (Of course this is strictly hypothetical, for a real celestial body that is non-rotating is drawn to a near-perfect sphere by its self-gravitation.)
The first image shows this planet with on the North pole a large planar surface. Nothing is rotating here, in this section the non-rotating situation is discussed. If a ball is released somewhere on this planar surface, and friction is low enough, it will move towards the point of lowest gravitational potential. If the friction is very low, but not zero, then the ball will oscillate back and forth over the North pole for a while, and will eventually come to rest on the North pole, because that point is closest to the center of gravity. 
The second image shows this planet with on the North pole a convex bowl. It is effectively a bowl, because wherever a ball is placed, it will roll towards the pole. The pole is the point of lowest gravitational potential of the bowl, the point closest to the center of gravity.
The third image shows the the planet itself. Each hemisphere is effectively a bowl, because wherever a ball is placed, it will roll towards the nearest pole. The poles are points of of lowest gravitational potential of the bowl, the points closest to the center of gravity. 
On a non-rotating oblate spheroid, the motion of a ball that is placed on the surface is influenced only by gravity. (More precisely: the resultant force of the force of gravity and the upwards force from the surface that the ball is resting on.)
There is of course no Coriolis force involved. This situation has nothing to do with any Coriolis effect.
When a ball is pushed away from the North pole, then gravity will return it to the North pole. If the friction is very low, but not zero, then the ball will oscillate back and forth over the North pole for a while, and will eventually come to rest on the North pole, the point closest to the center of gravity. The oscillation will not be harmonic oscillation, for the restoring force is not proportional to the distance to the center of oscillation. The closer to the equator the weaker the force towards the pole.
==== Motion of a Ball, co-rotating on the surface of a Rotating oblate Spheroid ====
Imagine a planet with the same shape as the Earth, same gravity, same rotation rate, but perfectly smooth. At any latitude, the amount of centripetal force is the amount that is needed for objects at that latitude to remain in circular motion, circumnavigating the planet's axis of rotation. <BR>
A ball, laid down at any latitude of the rotating oblate spheroid, at rest with respect to the surface of the rotating oblate spheroid, will stay where it is laid down; at every latitude there is dynamic equilibrium.
On Earth, water does not tend to flow to the poles and it does not tend to flow to the equator because there is dynamic equilibrium at every latitude.
The situation of a rotating turntable with a parabolic surface and the rotating Earth are very similar, at all distances to the axis of rotation there is dynamic equilibrium. Thus, the atmospheric layer is equally thick at every latitude.<BR>
On the rotating turntable, there is not only concentric circular motion as a stable orbit, elliptical motion with respect to the turntable's axis of rotation is a stable orbit too. As seen from a co-rotating point of view the eccenticity of the elliptial orbit appears as oscillations with half the period of the overall rotation rate.
In oceanography these oscillations are known to occur widely, and they are called inertial oscillations, and they have a period of 12 hours, or longer, if it is further away from the poles. In meteorology these oscillations are called inertial wind.<BR>
Reference for the phenomenon of inertial oscillations: the references of the American Meteorological Society Glossary, the entry about inertial oscillations
The inertial oscillations of ocean water, and inertial wind, can be accounted for by assessing the effects of gravity; the oblate spheroid shape of the planet Earth allows fluids on the surface to follow elliptical orbits around the Earth's axis of rotation. (This is of course a simplified picture, I'm restricting the description to the bare essentials.) 
Inertial oscillation of ocean water is started by a period of wind. This starting of an inertial oscillation is a shift from concentric circular orbit around the Earth's axis to elliptical orbit.
Recognizing that the inertial oscillations are in fact the eccentricity of an elliptical orbit is not a new discovery, of course. They are called 'inertial oscillations' exactly because of the analogy with eccentricity in the context of orbital dynamics.
=== Any questions left? ===
To answer any additional questions, I need to know exactly what the difficulty is. Please try to explain as clear as possible what exactly you don't understand, so that I can try and figure out a way to explain.
=== Thorougness ===
Yes, I wrote a very loooooooooong text again. Of course, if I would have written a terse reply William M Connolley would have said I was being evasive, or shallow, or whatever. There's no pleasing some people.<BR>
--Cleon Teunissen | Talk 04:01, 31 July 2005 (UTC)
replies: text: It's not how long your reply is. It's whether is specifically addresses William's criticism, that matters. Plus you really shouldn't assume what William will say before he says it - (assume good faith and all that). Theresa Knott  (a tenth stroke) 13:02, 31 July 2005 (UTC)
thread_title:  Reply to the main question of William M Connolley 

message: Yes, I wrote a very loooooooooong text again. Of course, if I would have written a terse reply William M Connolley would have said I was being evasive, or shallow, or whatever. There's no pleasing some people.<BR>
--Cleon Teunissen | Talk 04:01, 31 July 2005 (UTC)
replies: text: It's not how long your reply is. It's whether is specifically addresses William's criticism, that matters. Plus you really shouldn't assume what William will say before he says it - (assume good faith and all that). Theresa Knott  (a tenth stroke) 13:02, 31 July 2005 (UTC)
thread_title:  Thorougness 

message: : The coiolis effect is *not physics*: it is kinematics. William M. Connolley 19:51:33, 2005-07-31 (UTC).
:: BTW, note that CT's favourite ref - Persson - supports this: http://www.ap.cityu.edu.hk/Ap8813/References/Coriolis/Coriolis.pdf.
William, this is sheer dishonesty.<BR>
* Anders Persson does not see coordinate transformation as relevant at all in discussing meteorology. 
* Is is not clear whether Anders Persson has the same thing in mind as you have when he uses the word 'kinematics'. I have tried finding a description of what 'kinematics' can mean. The descriptions are wide apart, there are multple, sometimes vastly different meanings of the word 'kinematics', so it can never be simply assumed that someone else has the same meaning in mind.
* As far as I can tell, Anders persson associates the word 'kinematics' with applying for example conservation laws to perform calculations. If you apply a conservation law then you do not look into the actual physical mechanism, you apply the knowledge that in the end certain quantities must be seen to have been conserved (such as angular momentum) Anders Persson contrasts that with what he refers to as dynamics, where the actual forces are traced. As far as I can tell, Anders Persson uses the word 'kinematics' in a very different way from your use of it.
*Anders Persson states that in meteorology, kinematic approach (in the meaning Anders Persson has in mind) and dynamic approach supplement each other.
*Anders Persson emphasizes that for understanding what physics is taking place kinematics is no good, to understand you must see what force acts when.
If you don't believe me, then by all means you should write an email to Anders Persson. (I'm reluctant to give his email adress here in public, I found his e-adres pretty quickly by googling). I challenge you to put your money where your mouth is. I propose to raise the stakes: if I am mistaken, I will withdraw from the coriolis article, If you are wrong, you will withdraw. Do you accept the challenge? Or do you back away from it?
--Cleon Teunissen | Talk 20:29, 1 August 2005 (UTC)
thread_title:  Coordinate transformation is irrelevant for meteorology 

message: If(!) the earth were a perfect sphere and(!) it had the same qty of air and water then there would still be coriolis effects.  In the band of air and water about the equator.  Point proven.  Let's move on.  Paul Beardsell 14:48, 31 July 2005 (UTC)
replies: text: Well, I don't think it's provable. The fluid parts would distribute in such a way that there would be, in a limited area/volume something identical to an oblate spheroid. And of, course, on an oblate spheriod there is an arena for coriolis effects. Nah, it's too hypothetical anyway to really have physical meaning, I think. --Cleon Teunissen | Talk 15:02, 31 July 2005 (UTC)
thread_title: Coriolis effects on a perfect sphere

message: The Coriolis force appearing in the equation is just a way to explain the physics.Woodstone 22:02, July 31, 2005 (UTC)
:You cannot be serious: it has been emphasized that a coordinate transformation does not alter the physics taking place (obviously). A coordinate transformation has no explanatory power. A coordinate transformation does not reveal something that you didn't know before. 
:The word explain says it nicely: to explain is to unfold, to reveal what was hidden. Only when your understanding is moved to a deeper level is it an explanation. --Cleon Teunissen | Talk 22:27, 31 July 2005 (UTC)
thread_title:  Looking for an explanation 

message: William M Connolley has suggested that I did not provide refernces because the ideas presente were inventions of my own inventions. Here are references, I have been reporting published work.
My main sources of information have been the articles by the meteorogist Anders Persson.
Anders Persson is a widely published meteorologist.
In 2000 the Royal Meteorological Society published a series of three articles about the coriolis effect.
The article-titles of the issues of the year 2000
This article by Anders Persson, (PDF-file, 826 KB) On page 10 Anders Persson writes.<BR>
"For a stationary object on a rotating planet or a rotating parabolic surface the horizontal components of the centrifugal force is balanced by the horizontal component of the gravitational force of the planet and, on the turntable, the orizontal component of the weight of the body. In both cases the component of gravitation and gravity, perpendicular to the rotational axis, equals the centrifugal force."<BR>
[end quote]
This article by Anders Persson (PDF-file, 374 KB), published in the Bulletin of the American Meteorological Society describes the mechanism for the deflection of eastward movement and for westward movement:<BR>
Anders Persson writes:<BR>
Due to its ellipsoid shape, the gravitational forces balance the centrifugal force on any body, as long as it does not move When it moves, the balance is altered. For an eastward movement the centrifugal force is increased and the body is deflected toward the equator, to the right of the movement. For a westward movement the centrifugal force is weakened and can no longer balance the gravitational force, which is the  physical force that moves the body in the poleward direction to the right of the movement (Durran 1993; Durran and Domonkos 1996).
Durran, D. R., 1993: Is the Coriolis force really responsible for
the inertial oscillation? Bull. Amer. Meteor. Soc., 74, 2179–
2184; Corrigenda. Bull. Amer. Meteor. Soc., 75, 261<BR>
——, and S. K. Domonkos, 1996: An apparatus for demonstrating
the inertial oscillation. Bull. Amer. Meteor. Soc., 77, 557–559.
Massachusetts instutute of technology <BR>
Physics of Atmospheres and Oceans <BR>
Inertial circles - visualizing the Coriolis force: GFD VI  By John Marshall
Inertial circles - visualizing the Coriolis force: GFD VI <BR>
Professor John Marshall, Dept. of Earth, Atmospheric, and Planetary Sciences has included experimenting with ar rotating parabolical turntable in the atmospheric sciences education, to provide understanding of what is taking place.<BR>
Professor John Marshall writes:<BR>
The circular trajectories – which are called ‘inertial circles’ – are commonly observed in the atmosphere and ocean.<BR>
Dr. D.I. Benn of the University of Saint Andrews in Scotland writes:
Source of the quote from Dr D. I. Benn <BR>
Of all aspects of meteorology, the Coriolis effect is perhaps the most misunderstood, and generations of students have struggled with it. This is not because it is any harder than other aspects, but mainly because the explanations in many textbooks are misleading, if not downright wrong. For example, some books attempt to explain the Coriolis 'force' in terms of balls rolling over rotating turntables or similar analogies, but such explanations do not help, as the physics involved is completely 
different.<BR>
[...]<BR>
The best discussion of the Coriolis effect is in three recent articles by Anders Persson in the journal Weather . Understanding these still requires focused thought, but at least the explanations make sense (so it is a lot easier than trying to understand something that doesn't make sense!). The following discussion follows Persson. Ignore the stuff about rotating turntables and wandering polar bears in the textbooks. An excellent discussion (incorporating Persson's ideas) is given by Stull'  in Meteorology for Scientists and Engineers.
[end quote]
This concludes for now the list of my references.<BR>
--Cleon Teunissen | Talk 08:05, 1 August 2005 (UTC)
thread_title:  References  

message: :Of course, the physics on a rotating planet is different from the atmospheric physics on a non-rotating planet. But the physics (understood as the relative motion of parcels of air) on a rotating planet is the *same* whether you view that from the rotating system itself, or from outside the rotating system. William M. Connolley 21:33:43, 2005-07-31 (UTC).
So, what is the difference between the physical mechanisms on a rotating planet and the physical mechanisms on a non-rotating planet?
I checked the what links here page. There are over 50 links to the coriolis effect article, many about meteorological articles, and they link to the coriolis effect article in the expectation that the coriolis effect article wil explain the physical mechanisms that are involved.
William, in your opinion the expression 'Coriolis effect' should be associated exclusively with coordinate transformation. Coordinate transformation is unrelated to the physical mechanism of what is taking place, the coordinate transformation is part of the mathematical toolbox, like a computer is part of the toolbox of meteorologists.
Following your logic, the article about the 'Coriolis effect' should be about coordinate transformation only, without going into any physics.
{User:Woodstone has added the remark:
:Note that the Coriolis force is an apparent force, experienced in a rotating frame of coordinates.
Why would you want to write about meteorology in an article that is only about coordinate transformation? <BR>
Why would you wnat to write about the Coriolis flow meters in an article that is only about coordinate transformation?<BR> 
You do write about meteorology, and you name 'coriolis force' as a factor that is physically influencing the direction of the wind.
You are contradicting yourself, and you are not facing up to it. <BR>
--Cleon Teunissen | Talk 09:48, 1 August 2005 (UTC)
thread_title:  A challenge to face up to selfcontradictions 

message: What's the issue here?  Cleon provides a quote asserting that inertial circles exist.  Who says differently?  Paul Beardsell 10:44, 1 August 2005 (UTC)
thread_title:  Inertial circles 

message: How much of the previous discussion was merely Babylonian confusion?
  
Apart from what name we use for the dynamics depicted in the image, it appears we do agree about what is happening in that picture. Pull on the string and the rotation rate of the other ball goes up.
Angular Acceleration Accompanying Contraction is the dynamics that Gaspard Gustave Coriolis described in his 1835 paper. Gaspard Gustave Coriolis was dealing with machines. That is the historical origin.
Anyway, it would of course be ridiculous to try and explain the dynamics of Angular Acceleration Accompanying Contraction in terms of coordinate transform. 
Of course, in coordinate transformation to a rotating coordinate system only one coriolis term appears. There is only way to transform to a rotating coordinate system.
This is the history section of the coriolis effect article. Do you agree with it? It is well referenced.
If you think the history section is wrong, please say so.
--Cleon Teunissen | Talk 15:34, 1 August 2005 (UTC)
replies: text: Gaspard described a number of things.  All the things he described are not together the Coriolis effect.  As I understand it the Coriolis effect is that now described by the 1st paragraph of the article.  Paul Beardsell 16:00, 1 August 2005 (UTC)
thread_title:  Babylonian confusion 

message: William, I understand what you're doing.  The deflection is real from the rotating frame of reference.  And no frame of reference is any better than any other.  But the observed deflection is only "apparent" from that frame of reference.  A re-wording, just placing "apparent" elsewhere in the sentence should satisfy us both.  What say you?  Paul Beardsell 15:57, 1 August 2005 (UTC)
thread_title:  apparent 

message: Suppose that there is a huge gun, big enough to shoot something that shines so bright it can be seen from the Moon. This big gun is fired, a shot from the equator towards the north. The astronauts on the Moon see the projectile fly in a straight line. There is a whole battery of those guns, they are shooting a grid pattern. The astronauts see the entire grid of luminescent ammo travel along, in straigh line motion.
So: as far as ballistics is concerned there is a difference between seeing it from the Moon or seeing it from fixed-to-the-Earth. The astronauts on the Moon, rotation rate once per 28 days which is pretty close to zero, they do see the projectiles travel in straight lines, while an observer stationary with respect to the  Earth sees a curvilinear trajectory. Interestingly, the observer on Earth sees curvilinear trajectories, but the arrangement, the grid of projectiles has the same form, no distortion of the grid. And of course: coordinate transformation is global, the whole picture is rotated.
--Cleon Teunissen | Talk 21:47, 1 August 2005 (UTC)
thread_title:  What do you see from the Moon? 

message: In the current article, Woodstone has written about the meaning of the red arrows in the diagram, as seen from a non-rotating point of view.
I would like to formulate it as follows: As seen from the non-rotating point of view, the small red arrow on the flow from south to north (pointing sideways) can be interpreted in terms of conservation of angular momentum. The radius of circular motion decreases, so that will be accompanied by an increase of angular velocity, showing up as increase of  velocity with respect to the Earth.
In the case of the flow from west to east there is a situation that looks a bit like cars going round on a banked circuit. How high up the bank the car will go depends on the speed of the car, (the driver, once he has steered into the banked curve, pretty much has to follow where his momentum leads him, otherwise he'll likely lose grip).
There may be a lane that is cleaner, and if the driver is going faster than the fastest possible speed for that clean lane, he will drift outside, not having enough grip.
Air that is flowing with respect to the Earth in west-to-east direction is in that kind of situation; it's speeding.
That is what the two diagrams on the right stand for.<BR>
The whole line of thinking that is looking at the overall angular momentum does not need to consider the coordinate transformation, for that line of thinking is looking at it from a non-rotating point of view in the first place. --Cleon Teunissen | Talk 12:25, 2 August 2005 (UTC)
thread_title:  The meaning of the red arrows 

message: I was interested in the article as it covers most of the issues related to the Coriolis force issue and shows animated pictures that ought to help the reader understand things in an innovative way.
I come from the country of Coriolis and Foucault and there may be some cultural difference between what we call the Coriolis force here nowadays and what they call it in the States. We actually prefer to speak about Coriolis acceleration. 
I am puzzled by a number of things, though.
1. the first sentence leaves me unsatisfied, as an effect cannot be a force: these are different categories of things and they may be (they are indeed!) related, but please, explain how. I have seen in the discussion that the 'reality' of the Coriolis force is being questioned, which may be why the author feels more comfortable to talk about effect?  But this business of whether the Coriolis force is real or not is an old debate, which has been around in high school physics classes for ever, comes up as well for the centrifugal force and can be raised also for gravity, if one think of it in the framework of general relativity ! This is actually non-issue, as forces are not universals, but rather "things" that are felt or measured within a special reference frame. If you are sitting on a merry-go-round, it is easy to feel the centrifugal force and you won't question its existence for long! If you are watching the merry-go-round from the outside, then you may question the force and consider it as a trick for engineers to balance the set of forces that is applied to the arm that hold the gondola to the rotating axis. But, this is not a very deep discussion any more!
2. the first definition of the Coriolis force given in the article is what we call here conservation of momentum: if a ice-skater stretches her arms or pulls them to her body while rotating on herself, her speed will change. Kinetic energy and momentum will be conserved. We don't connect this here to a Coriolis effect.
3. the only Coriolis effect that we speak about here is the effect related to the Coriolis force that arises when you analyze the forces that are applied to a mobile, when you use a non-uniformly moving reference frame. The sets of motion equations becomes a bit more complicated than in a Galilean frame (one that moves in straight line at constant speed) and a small term related to the vectorial velocity with respect to the frame comes up, which is the Coriolis force. This definition should somehow be given explicitly in the text, even if Wikipedia is not meant for pHDs, as this is taught to seniors in high schools now or to 1st year university students.  Then every
thing follows: there is no Coriolis force in a Galilean reference frame, it only shows up if the frame is accelerated.  And you can develop all the nice and puzzling features that are shown in the article.
--Ifsteelman 06:57, 11 August 2005 (UTC)
thread_title:  Comments from Coriolis' country... 

message: :there is no Coriolis force in a Galilean reference frame, it only shows up if the frame is accelerated.  --Ifsteelman 06:57, 11 August 2005 (UTC)
replies: text: Rotation (at constant angular velocity) is an acceleration.  In physics.  (And it is physics we are dealing with here - the words have precise meanings and the common sensical use of the words is often unhelpful - try telling a man holding a brick at arm's length that he is doing no work).  The Coriolis effect is only to do with rotation.  Any apparent deflection  owing to other accelerations is NOT called the Coriolis effect!  Please refer to the first paragraph of the article.  Paul Beardsell 09:59, 20 August 2005 (UTC)
thread_title:  What do you mean by 'showing up'? 

message: :This is actually non-issue, [...] If you are sitting on a merry-go-round, it is easy to feel the centrifugal force and you won't question its existence for long! --Ifsteelman 06:57, 11 August 2005 (UTC)
thread_title:  It is indeed a non-issue 

message: The extensive rewrite I did is based on the content of the following references, as listed at the bottom of the current coriolis effet article.
The authors of the articles are prominent meteorologists. --Cleon Teunissen | Talk 19:41, 18 August 2005 (UTC)
thread_title:  Extensive rewrite August 18th, the references  

message: David McIntyre has made number of animations that show how object would move (and appear to move) in the case of the approximation of the Earth as a perfeft sphere. David McIntyre's animations
David McIntyre animations show that under the assumption of a perfectly spherical Earth the pattern of motion called 'inertial oscillation' cannot possibly occur.
The animation on the right shows the pattern of motion of inertial oscillation, as seen from a non-rotating point of view. That is: that animation represents what you get if you transform the pattern of motion of atmospheric inertial oscillation from a co-rotating point of view to a non-rotating point of view. 
All air mass on the Earth is subject to a poleward pull of a component of gravitation, each hemisphere to its own pole. In meterology that poleward pull must be taken into account, and of course it is taken into account in settting up the equations of motion, otherwise the computermodels wouldn't work at all. 
If the equation of motion would be set up for a non-rotating coordinate system, it would contain a term of the form: <BR>
 2m(\omega \times v) * sin(latitude) because of the rotational dynamcis that is at play. <BR>
--Cleon Teunissen | Talk 20:14, 18 August 2005 (UTC)
replies: text: Yeah, but this has nothing to do with the Coriolis effect in the atmosphere.  The shape of the surface is only important for sliding pucks.  the atmosphere is a fluid and finds its own level.  If the earth were a cube there would still be the Coriolis effect.  There would still be cyclonic weather systems.  Paul Beardsell 09:52, 20 August 2005 (UTC)
thread_title:  The animations by David H. McIntyre 

message: For the nth time:  Gravity and the coriolis effect are unrelated!  All of these pucks sliding on specially shaped surfaces are to demonstrate the coriolis force by eliminating the predominant forces (by balancing the force of gravity and the centrifugal "force") on the puck so as to allow the coriolis effect to be seen.  This needs to be made plain in the article.  In the atmosphere, with everything floating in everything else, those forces do not need to be balanced for the coriolis effect to be noticed.  That's the nature of a fluid.  And that is what the atmosphere is!  Paul Beardsell 09:47, 20 August 2005 (UTC)
thread_title:  Gravity and the Coriolis effect! 

message: Also (and this follows simply from the previous section) the shape of the earth is unimportant when describing the Coriolis effect in the atmosphere.  Were the Earth a cube cyclonic weather patterns would still occur:  One way in the north, the other in the south BECAUSE the atmosphere is a fluid and, in a fluid, the shape of the container is immaterial.  All of Cleon's arguments as to the sideways component of gravity owing to the particular shape of the Earth would still be irrelevant when discussing the Coriolis effect in the atmosphere.  Sliding pucks?  OK.  Cyclones?  No.  Paul Beardsell 10:16, 20 August 2005 (UTC)
thread_title:  Shape of the Earth and the Coriolis effect in the atmosphere! 

message: Special relativity:  Unlike linear velocity, angular velocity is not relative.  Two people moving linearly relative to one another can not say who is at rest.  But two people rotating relative to each other can soon determine which is the one who is really rotating.  Throw a ball from one to the other and the rotating one will observe the Coriolis effect.  Therefore the deflection observed is not *real*.  Paul Beardsell 18:06, 21 August 2005 (UTC)
thread_title:  Rotation is absolute not relative, deviation of free moving object is not real 

message: I did a count of articles in the 
what links here pages of the coriolis effect article. About thirty of them are about meterological subjects; all those articles expect the coriolis effect article to deliver the goods.
There has been a suggestion for a split into two articles. One article would concentrate on the the meaning of the expression 'coriolis effect' in ballistics, as displayed in the illustration. A second article would be about what happens in the atmosphere. 
I support organizing such a split.
I retrospect it would have been helpful if the rotational dynamics that is taken into account in meteorology would be called 'Ferrel effect' since he was the first to correctly described it. 
I don't particularly mind what name is used for this or that, as long as the physics is described correctly. --Cleon Teunissen | Talk 18:12, 21 August 2005 (UTC)
thread_title:  Thirty articles about meteorolical subjects link to the coriolis effect articel 

message: I have inserted my proposed new version (with the sole change of removing "fictitious", but I won't care if someone re-adds it) as discussed above.
Is it time to archive all the talk on this page?
William M. Connolley 11:09:41, 2005-08-22 
(UTC).
:Yes the Talk page is humongous. It badly needs to be archived. --Cleon Teunissen | Talk 11:19, 22 August 2005 (UTC)
thread_title:  New version inserted 

message: I really like this new version.  Great improvement.  Long live the one Coriolis effect.  Paul Beardsell 02:48, 23 August 2005 (UTC)
thread_title:  Hey! 

message: Satellite orbits and ballistic trajectories are part of one and the same group of trajectories.
Satellite orbits can be circular or elliptical, if the satellite orbit is elliptical then the Earth is at one focus of the ellipse.
The parabolic trajectory of the vomit comet during weightlessness creating flight is in actual fact an elliptical trajectory with the Earth at one focus of the ellipse. In the case of the vomit comet the elliptical trajectory is smaller than the radius of the Earth, so the duration of weighlessness is limited, but during the period of weightlessness the mechanics for the people inside the airplane is the same as for astronauts on a space station: the orbital mechanics of satellite orbit. 
A satellite orbit is always planar, and the center of gravitation of the Earth is in the plane of the orbit. If you intersect the plane of the satellite orbit with the surface of the Earth you get a great circle.
If you have a circular satellite orbit, tilted with respect to the Earth's equator, then as seen by an observer who is stationary with respect to the Earth, the satellite is oscillating, with the equator as the midpoint. As seen from Earth the satellite is from time to time moving parallel to a latitude line. Motion parallel to a latitude line, either east-to-west or west-to-east, is always followed by moving towards the equator, to the other hemisphere. Any ballistic trajectory has the property that when it is projected on the surface of the Earth, the projected line is a section of a great circle --Cleon Teunissen | Talk 06:34, 23 August 2005 (UTC)
thread_title:  Ballistic trajectories and great circles