Tsunamis, etc

[Jim Green <JMGreen@sisna.com>]

I think that I now know why some of my msgs are garbled -- it is due to my
reformatting of the quoted material.   There should be none in the original
material.   But this msg should NOT garbled, because I will not reformat
anything.  Please comment.  TX Jim

Now to the point of the current msg:

At 11:14 AM 4/1/98 -0600, Brian wrote:

> I did as Chuck suggested and reviewed Jim's web presentation - which is
> nicely done in my view.=20

I thank Brian and Chuck for their kind comments re the web page.

NB the following concerns the _water tides_ in the Earth's oceans.

Brian's observations (see below) expose a weak point in my various
statements:=20


Many/most/all oceanographers hold that a tidal "wave" can not run faster=
 than
sqrt(gd).  (ie 400-500mi/hr)  See the citations on the web page noted above
for
derivations and other confirmations of this relation.

BUT Brian's observations are quite valid -- although I have not checked the
data on the co-tidal map on the my web page.   David Bowman flatly decries=
 my
position.  He does agree, I think,  that in the case of a tsunami -- a=
 pulsed
wave -- this might well be valid, but for a _driven_ wave such as a=
 purported
"tidal bulge", it is not.  (His position is buried in his long post of
Tues). =20

I wish that I could resolve this mish mash.   Can anyone help????   Is there
someone who would review his comments and those below and report?  It might=
 be
helpful to consult an open minded (:-) geophysicist.  There ain't one here
-- I
mean any sort of geophysicist.  Everyone here is clearly open minded. (:-)=
=20

Last year David did respond to my request for help with the following
question:

Consider a long straight iron wire situated such that a magnet could be run
parallel to and close to the wire.  As the magnet moves what is the shape of
the wire -- with the following parameters: magnet moves 1) faster than the
natural wave velocity ) at this velocity and 3) slower.   (David, I have
studied but not yet taken the time completely sort through your analysis --=
 I
must plod along without the help of Matematica -- but I should not=
 contradict
you until I do. (:-))  I would be eternally grateful if someone were to take
interest here -- well maybe not _eternally_, but surely a whole bunch.

However, I think that there is sufficient confirmed data to show that tidal
motion is NOT correlated in any significant way to the Moon's transit.

And I will be consulting with the McDonald people and others to see if they
have come up with a better co-tidal map than what I have.

Jim green
JMGreen@sisna.com
   =20
> But I have taken the liberty of extracting a little
> of Jim's text for review here below. The world map to which he refers shows
> lines of isochronal tides. The map projection is not particularly helpful
> in one respect - if one would like to see where the ocean tide runs more or
> less parallel to the meridians as in the North Pacific, it is necessary to
> imagine their projected shape which is not a straight line of course.
> I direct you particularly to his second and third paragraph quoted below:
>
> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 [Jim Green]
> "The map shows that the speed of the tides is usually not at the speed of
> the Moon -- about 15deg/hr. This angular velocity at the equator would be
> about 1000mi/hr or about 1600km/hr and at 60 degrees north or south
> latitude would be about 800km/hr. [ 8 ] However, in the region between
> Japan and New Guinea, the map shows that the motion is westward at less
> than 300 km/hr."
>
> "In the previous example, the high water crest travels the 1000 miles from
Los
> Angeles to Seattle in the same one hour interval as it takes to travel the
> 100 miles from San Diego to Los Angeles."=20
>
> "Indeed the speed of the tides can not be as high as 1600 km/hr. For
> shallow water waves -- waves with wavelength much greater than the depth of
> the water basin like tidal crests -- the speed is given as sqrt(gd) with g
> =3D 9.81 m/s=B2 and d =3D the basin depth. [ 9 ] The ocean depth is about=
 3-5km
> so the maximum speed of an ocean wave is of the order of 600-800km/hr. So
> any so called "tidal bulge" motion could not keep up with the Moon except
> at a latitude greater than about 60 degrees. [ 9 ]
> [Cf. Appendix B for details of these calculations.] "
> --------------------------------------------------------------------------
>
>
>
> On the face of it, Jim appears to argue that the oceanic tide cannot run at
> 1600 km/hr (his third para)=A0=A0 but that the tide DOES in fact run at=
 1000
> miles/hr
> between LA and Seattle (his second para). The world chart appears to show
> quite a few places in the deep ocean where the tide in fact runs faster
> than 1600 km/hr so I am at a loss to justify his position on this.
>
> =A0 But his graphic world model (the numbers are apparently synthesized) is=
 a
> vivid illustration of Jim's main thrust, I suggest - the tidal progression
> is very, very untidy - very far from a stately progression of meridional
> change round the globe.
>
>
> Whatcott=A0=A0 Altus OK
> =20
Jim Green
JMGreen@sisna.com

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