Ocean Tides

[Jim Green <JMGreen@SISNA.COM>]

>          A small footnote on CoTidal Maps,  Thomas Young of two slits and
> Hieroglyphics fame was the inventor of these. He and Laplace both work out
> what is the basis of modern tidal theory - beyond Newtons simple bulge
> model. Young likened tidal flow to a driven pendulum, where the driving
> force is the lunar-solar gravity and the natural frequency of the pendulum
> (oscillator) is determined by the fluid in the basin.
>          I hope this helps.

This does help.  I hope that others are listening.  But remember that there
are dozens of interacting basins. Map 13 iirc on my web page shows the
basins of the world.  The oceans are divided by various land masses and
ocean ridges -- each basin with its own natural frequency and with various
coupling coefficients to contiguous basins and with various driving forces
with various driving frequencies -- due to the Moon, Sun, and even some
planets -- as strange as that may seem.

From this it is never contemplated to _calculate_ the tides in any given
location.  What is done by NOAA is to measure water level v time in dozens
of locations over the Earth and use a Fourier-like analysis to do the
predictions.  The result is that usually (maybe almost never) does high
water match any of these periods.  In fact there are nodes where there is
never a "high tide."

Now can we get back to the movement of the Earth.

Currently the angle between the spin axis and the orbital plane is ~23o.

As the Earth precesses does that angle ever change????

Jim

Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen