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Sorry to be late in replying on this topic. I was travelling for much of August.

Gary L, you wrote:
"Note, I am not saying that the use of a "fiction" might not be useful in 
making an explanation for what an observer is seeing just like you telling 
your young child that the stork brought the new baby."

If you really believe that that's a legitimate comparison, then you have been 
seriously misled. The replies you got from Peter H. were excellent and right 
on the money, so I will only add a little more for now...

I do understand (I think) why you have some misgivings about the use of 
Coriolis force in describing various phenomena since it has been grossly 
abused in some explanations of simple things --the notorious tall tales about 
the swirling of common sink drains in the northern and southern hemispheres 
being the worst abuse. But I can assure you that there are many phenomena in 
physics which benefit greatly from the use of a rotating frame of reference 
--which necessarily includes centrifugal acceleration and Coriolis 
acceleration. Some among these that come to mind off the top of my head are 
the ocean tides, ocean circulation generally, most of meteorology, 
gravitational phenomena like the stability of the Lagrangian points, common 
laboratory centrifuges, spacecraft centrifuges (remember the one imagined in 
the movie 2001 over forty years ago?), and a great many other circumstances. 
Any time you have a large number of objects participating in a common 
rotation, especially when fluids are involved, you will generally find that 
physics is much easier to work in a rotating frame of reference. And these 
frames of reference are not used merely to teach 'young children' as you've 
suggested above. They're used by professional physicists without the 
slightest misgivings. The Coriolis and centrifugal accelerations are rigorous 
physics.

The NavList posts which previously claimed that it was incorrect to understand 
the behavior of a gyrocompass by reference to Coriolis force were WRONG. You 
don't necessarily have to work in a rotating frame of reference, if such 
things confuse you, but it is legitimate to do so. Whether it is enlightening 
or not depends significantly on the background of the student.

Somewhere else, you asked about the behavior of a gyrocompass near the equator 
since the equation you know for Coriolis has a factor of sin(Latitude) in it. 
That equation does not properly describe the Coriolis acceleration. It is a 
shortened version given to pilots and others who need only a basic 
understanding of the phenomenon. The Coriolis acceleration is not zero at the 
equator (as the equation you learned implies). Rather, something unusual 
happens to it in low latitudes. If a plane is flying east above the equator, 
in what direction does the Coriolis acceleration point?? I will leave that as 
something for you to explore on your own...

-FER




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