Is centrifugal force caused tide?

D H

They do attribute the tides to the Sun and Moon, but they do so badly. Very badly. At least in my opinion. You be the judge. Here's just a tiny sampling of what you get if you go to books.google.com and search for "tides centrifugal force":

http://books.google.com/books?id=eAq...page&q&f=false

http://books.google.com/books?id=0Jk...page&q&f=false

http://books.google.com/books?id=h2-...page&q&f=false

http://books.google.com/books?id=uuf...page&q&f=false

The U.S. government's National Oceanographic and Atmospheric Administration (NOAA) starts out right here, but get it wrong on the following page. NOAA not only gets it wrong again here and here, they display a fundamental misunderstanding of the concepts of orbits, too. Centrifugal force is not needed to explain the tides, and it is not needed to explain orbits. (Misunderstanding orbits is apparently widespread amongst oceanographers).

The problem is our teachers. Students don't know the correct answer to what causes the tides (gravity gradient) because most teachers don't know -- even subject matter experts. See Jouni Viiri, Students’ understanding of tides, Phys. Educ. 35(2) March 2000.

olivermsun

In your links above, I noticed that the books were written by a geologist, a marine biologist, a geophysicist, and an expert in marine biomechanics. The NOAA website meanwhile references a textbook written by another geologist.

Also, the explanation in the geophysicist's book actually looks similar to that (briefly) given in a lecture by Feynman.

I know that all these people may all look like "oceanographers" to the layman, but I wouldn't necessarily want to extrapolate from this sample to infer a "widespread" misunderstanding of tides among (physical) oceanographers (who study the tides, among other things).

D H

First off, I challenge you to find an oceanography textbook that properly explain the tidal driving forces. There are a few that get it right, but there are far more that get the explanation fundamentally wrong.

Secondly, by a happy set of circumstances, sometimes three wrongs do make a right. Even though that centrifugal force explanation is wrong, wrong, wrong, the end result is correct.

Thirdly, that two bulge theory of the tides is itself fundamentally flawed. While that is how tides would behave on a water world planet, that is not how the tides behave on our planet, with only 70% of the surface covered by water. That 30% percent of the surface that is land has a profound effect on the tides. The two bulge theory of the tides (Newton's equilibrium theory) cannot even come close to explaining why, for example, that no matter what time of day it is, you can always find some spot in the North Sea at high tide. There aren't two tidal bulges in the oceans. There are instead a number of amphidromic systems.

What's needed to explain the tides on our planet is a dynamical theory of the tides. Laplace started developing this theory. George Darwin (Charles Darwin's son) and A.T. Doodson pretty much put the finishing touches on the theory. Modern oceanography science extends this work by better modeling and observations of those amphidromic systems.

The theory outlines how tides behave in terms of frequency domain analysis. Those driving frequencies have different magnitudes and different lags at different points on the surface of the Earth. The dynamic theory of the tides explains what those driving frequencies are and provides a big picture view of those amphidromic circulations. However, modeling the magnitudes and phase lags of those tidal forcing functions at any specific point on the surface is very ad hoc.

olivermsun

I referred to one earlier, the Introduction to Physical Oceanography, by Robert H. Stewart and available online at http://oceanworld.tamu.edu. Also, after I saw your reply, I borrowed the first introductory textbook that I could find on a nearby colleague's bookshelf: Descriptive Physical Oceanography, by Lynn Talley and others. Both of these works were written by physical oceanographers and, upon casual inspection, appear to contain correct descriptions of the tide generating potential.

Interesting, that.

Also, I believe I did make a comment on the importance of basins to the actual tides in the earlier post that you replied to.