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-----Original Message-----
From: Jim Green [mailto:JMGreen@SISNA.COM]
Sent: Sunday, October 21, 2001 7:15 PM
To: PHYS-L@lists.nau.edu
Subject: Re: Tide article
Our tide clock was purchased in Los Angeles; it was not made "for"
any particular location. Indeed, as I pointed out, the hand
completes two cycles each "mean lunar day" which is not a function
of location. Also as I mentioned, the clock keeps excellent *long
term* track of the tides. To expand on what I said before, there
are seasonal as well as biweekly variations that drive the tidal
extremes temporarily away from the specific times predicted by the
clock. But if the clock is, for instance, set to properly predict
spring tides in July, it will be found to properly predict spring
tides *every* July for years on end (as long as the timing
mechanism functions properly and the batteries don't die.)
John, I will not "debate" you re this -- I have stated my
understanding
from study and research -- well my student's research -- down
the road from
John Denker. The list -- as Sam Donaldson says -- can take
it for what
they think it is worth. I think that no one gives much of
a damn about
this anyway.
NOAA gave us their raw strip chart recordings of the tidal data at the
Atlantic City Pier. (Come to think about it, I think that I
may still have
the rolls, if anyone wants them. They were recorded by people at the
nearby FAA Tech Center (Fat City -- my how they hate that) ie
Atlantic City
Airport). We purchased further data from NOAA (not
necessary any longer
-- it is on the web for many many locations world wide) The students
derived an equation for the vertical force v time at those
locations (I
think -- maybe it was the potential) due to the Sun and Moon.
And plotted
both the tide and the force jointly on one strip chart. (Some of the
details are now foggy as this was >ten yr ago)
Both our results and NOAA's calculations showed no
correlation of high
water or Spring Tide to anything: Moon or Sun position, Moon or Sun
period, etc etc. for any location (except for amphidromic points)
The cobbled force equation included contributions from the following:
M2......12.42hr..Principal Lunar -- The period used by
the NewZeland
site
S2.......12.00.....Principal Solar..........
N2.......12.66.....Lunar Elliptic...........
K2........11.97....Luni-Solar Semi-Diurnal..
K1........23.93....Luni-Solar Diurnal.......
O1........25.82....Principal Lunar Diurnal -- I assume
= John's Mean
Lunar Day
P1.........24.07....Principal Solar Diurnal..
The above together with even the 19 yr Moon cycle -- mostly
because the
students got carried away by the idea of accuracy
Now the variation John observes within one month or season is
expected and
may just be due to the variation of the period of the total
force due to
the combination of the several periods of the Sun and the
several periods
of the Moon. If the claim is that the period between successive high
waters is constant over infinity, Puget Sound would seem to
be a very
special place. I did hear that someone sighted a sea
"thing" with a very
long neck there. (Come to think about it, it is conceivable that the
Sound resonates at one of the myriad of driving frequencies
--Humm -- but
then the tides there would be very high -- I donno) But, if the 19yr
cycle is considered, I would be very surprised if even the
sea thing could
keep his tide clock accurate over THIS time period even
with Eveready
Batteries.
Jim