Re: Moon's synchronism

[Jim Green <JMGreen@sisna.com>]

At 06:52 AM 3/31/98 -0600, Brian wrote:

> This is a very clear position statement. I suspect Jim has in mind bulk
> transport rather than local elliptical motion over a rather modest vertical
> (deep ocean) extent - but I expect Jim has some more sophisticated basis
> for this position.
> I would like to hear the basis for his position.

Neither, Brian.=A0 I am referring to the velocity of=A0 a surface, gravity,=
 water
wave -- not to ocean "currents" or to the water molecule motion.=A0 Remember
that
in wave motion there is no net matter motion.=A0 The wave velocity depends o=
n
the
basin depth.=A0 In the case of the oceans the depth is shallow compared to=
 the
supposed wavelength -- about half the Earth's circumference.=A0=A0 But that
circumference depends on latitude.=A0=A0 At the equator a "tidal bulge"=
 would have
to travel at ~1000 mi/hr =3D ~1600km/hr.=A0 The wave velocity for these=
 "shallow"
waves is about sqrt(gd), where g=3D~10m/s/s and d=3D~4000m or so, thus
v=3D~450mi/hr.=A0 Now depending on the latitude and the current position of=
 the
Moon, this means that a tidal bulge/wave could not keep up with the Moon's
transit -- below something like 60o latitude. QED.=A0 This calculation is
covered
on my WWW page and references given there.

Jim Green
JMGreen@sisna.com

http://www.sisna.com/users/jmgreen