Jeff Morris wrote:

"Nav" wrote in message
...


Peter S/Y Anicula wrote:


"Nav" wrote



Sigh. Look you can say what you like but it is the imbalance of
force between the centrifigal and gravitational forces that causes
the two tides.


That's the explanation that you advocate. That is one out of several
explanation models.


Among simple explanations it's the one that is most accurate. How's that?



If the moon stopped its rotation around the earth and was "falling"
toward the earth, there would still be two bulges.
Anyone who claims otherwise clearly haven't understood what is
happening.


Yes that's right but the bulges would be small. I think the problem
probably stems back to Newton who suggested that gravity could explain
the tides. There is no doubt that gravity can produce tidal forces but
we are talking about the real tides on Earth. These are produced by the
imbalance of gravity and centrifugal (inertial) forces. This model
predicts larger tides than are seen but that leads to greater insight
too. The tides are smaller than expected because of friction and land
masses. While your differential gravity explanation can produce a tide
"similar" to that observed it does not explain it -unless you assume the
land masses don't exist. Do you see my point of view now?



Are you really claiming that the "open ocean" tides are over 100 feet, but the
land masses reduce them to under 10 feet?

No, I'm not saying the tides are 100 foot. Where did you get that
idea/number from? What I'm saying is that the land masses and shallow
water impede water flow and reduce global tidal heights. This is a big
effect in oceanography.

The tides have been studied in
considerable detail for the last few hundred years, and the scientists have been
quite happy with the "differential" model. Do you really think that a different
model that gives a radically different answer could actually be correct?

Scientists who model the oceans use a model in which the tides are
produced by the difference in centrifugal and gravity forces. Their
equations explicity include the orbital period of the moon -it's neither
negligible comaprted to "differential gravity" nor does it just cancel
leaving only gravity terms in the equations (that is the result of
ignoring the higher order terms whose magnitudes are comparable to the
tidal effect itself). Look at the NOAA pages to see what causes the
tides Jeff! :-)

Cheers