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 AA25101; Wed, 14 Dec 1994 12:30:35 -0800 Return-Path: <westes@usc.com-DeleteThis> Received: from uucp4.netcom.com by hplms26.hpl.hp.com with SMTP (1.36.108.4/15.5+ECS 3.3+HPL1.1S) id AA10214; Wed, 14 Dec 1994 12:30:58 -0800 Received: from localhost by netcomsv.netcom.com with UUCP (8.6.4/SMI-4.1) id MAA22861; Wed, 14 Dec 1994 12:15:58 -0800 Received: by usc.com (NX5.67d/NX3.0M) id AA02272; Wed, 14 Dec 94 12:13:56 -0800 From: Will Estes <westes@usc.com-DeleteThis> Message-Id: <9412142013.AA02272@usc.com-DeleteThis> Subject: Re: Re[3]: Tide Data To: wind_talk@opus.hpl.hp.com-DeleteThis Date: Wed, 14 Dec 1994 12:13:55 -0800 (PST) In-Reply-To: <9412141943.AA13317@zonker.hpl.hp.com-DeleteThis> from "Ken Poulton" at Dec 14, 94 11:44:42 am X-Mailer: ELM [version 2.4 PL23] Content-Type: text Content-Length: 1165
'Ken Poulton says:'
> > What I would really like to know is a RULE OF THUMB which would allow
> > me to figure out the percentage of full current as a function of time
> > (relative to high/low tides).
>
> It's site dependent. For the GG, the lag from high/low tide to slack
> water is about two hours!
Wow.... Not being an EE, I didn't follow your analogy to transmission wire, but
maybe the layman's explanation is the following: The reason that slack water follows
high tide is that near shore the force of the water pushing back out equalizes with the
force pushing the water in much sooner than it does in the channel. This seems to
make sense since the channel is much deeper, and the water only has the resistance of more
water to push against in the channel, whereas close to shore there is less-and-less water
and more-and-more land.
If that's right, then the current *near-shore* *is* the first derivative (or slope) of the
high-low tide waveform. It's just the current in *the channel* that shows a lag from
this value.
-- Thanks, Will Estes Internet: westes@usc.com-DeleteThis U.S. Computer Saratoga, CA 95070
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