Received: from hplms26.hpl.hp.com by opus.hpl.hp.com with SMTP (1.37.109.8/15.5+ECS 3.3+HPL1.1) id AA28412; Fri, 25 Aug 1995 14:58:07 -0700 Return-Path: <hoagland@sfgate.com-DeleteThis> Received: from sfgate.com (cyber.sfgate.com) by hplms26.hpl.hp.com with SMTP ($Revision: 1.36.108.11 $/15.5+ECS 3.3+HPL1.1S) id AA008817952; Fri, 25 Aug 1995 14:59:12 -0700 Received: from DaveH.sfgate.com by sfgate.com (smail 3.1.29.1) with SMTP id m0sm6as-00013cC; Fri, 25 Aug 95 14:47 PDT Date: Fri, 25 Aug 95 13:52:03 PDT From: Dave Hoagland <hoagland@sfgate.com-DeleteThis> Subject: Re: Re[2]: WIND_TALK digest 63 To: wind_talk@opus.hpl.hp.com-DeleteThis X-Mailer: Chameleon ARM_55, TCP/IP for Windows, NetManage Inc. Message-Id: <Chameleon.950825145133.hoagland@DaveH.sfgate.com-DeleteThis> Content-Type: TEXT/PLAIN; charset=US-ASCII
>Problem with this analogy, I believe, is that it is WRONG!
>Think a bit. 6 hrs from San Diego (or Hawaii or Equador) to get to the
>Gate and then it slows down enough to take 6 hours to only go a few
>miles? I don't think so. Why would it slow down? What absorbed the
>energy? Tides are explained well by Relativity.
>you can think of tides as a blanket over a bed where you, acting as
>gravity, pull on the center of the blanket and it rises towards you.
>The parts of the blanket all move just a bit towards you, but they don't
>really flow far. Relativity explains why we get two peaks and not
>just one (the way I understand it....).
It's a fact that the tide is approximately six hrs off from the gate to Rio.
This is obviously explained by the fact that all the water must pass
through a narrow channel (Golden Gate) to get into the Bay, then up
another channel (the river). This is a local phenomena. Also, Bob stated
that the trough (low tide) is six hours behind the crest (high tide) which
again is a fact. He did not say it takes six hours to get from Hawaii or
whatever to get here.
Whether this analogy is accurate however, beats the hell out of me.
I read an interesting piece on tides somewhere, I can't recall the
details but the gist of it was that the ocean tends to bulge towards
the moon (gravitational pull) tending to remain somewhat stationary
as the earth rotates under it. In other words the tides are caused by the
earth moving in relation to the water, not the water moving in relation
to the earth! To use those electrical terms again, the water leads and lags
the coastline due to the gravitational attraction of the moon which is
relatively stationary to the earth within a 24 hr period. If you diagram
this on paper you will see that the bulge of the ocean toward the moon
does act like a wave with 6 hrs (1/4 earth revolution) between the
trough and crest. I still don't understand the damn tide tables though.
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Name: Dave Hoagland
E-mail: hoagland@sfgate.com-DeleteThis
08/25/95 13:52:03
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