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Article #39Re: A question for the Meteo Data ???
From: Tim Gregg
Date: Sat, 09 Jun 2001 15:30
Date: Sat, 09 Jun 2001 15:30
56 lines
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3793 bytes
I was hoping to avoid this since it's far from a simple problem; therefor my comment about "exercise for the student". According to Kepplers Laws, a body in orbit about another traces out the same area per unit time; therefor when it is farther away, near apogee (not the correct word, apogee is specific to orbits about the earth, but I can't remember what the correct word is; some help anaybody?) the angle traced out per unit time is smaller than the average, or what it would be if the orbit were perfectly circular. Now, viewed from above in the totally politically incorrect northern hemishpere-centric view, both the earths rotation and its orbit about the sun are counter-clockwise. I will leave it to you to work out what that would do to the apparent position of the sun in the sky. Further complicating the problem, the plane of the earths rotation is set at an angle of 21� from the plane of the earths orbit, and we are standing on a sphere approximately halfway up from the equator. As I said, it's not a simple problem and would tax practically anybodys powers of visualization. Possibly for a little help, look for "the equation of time" and discussions of the corrections which need to be applied to sundials over the course of a year (that's right, for the same reason that sunrise and sunset times don't progress evenly, sundials run either fast or slow except for two days a year.) Good luck, Mr. Phelps! "Hugh Williams (London)" wrote: > Tim, > > Can you be more specific ? I'll hear from your answer. > > Thanks. > > Hugh > > "Tim Gregg" <timgregg@bestweb.net> ????? > news:3B21A409.85EF72F3@bestweb.net... > > > > > > "Hugh Williams (London)" wrote: > > > > > Jun 2001 LHR (London, UK) > > > Well, I don't understand why the SR times remaining at a certain period > > > (from 12/6 to 22/6 ) where it is occurred earlier than the SS times > > > indicated (from the period 18/6 to 29/6 ) in the above data. > > > > > > > It's due to the fact that the earths orbit about the sun is not perfectly > > circular; that apogee (aposol?? I forget) occurs in the northern > hemisphere > > summer, and therefor the earth is moving slower in its orbit than the > yearly > > average. I will leave working out the details as an exercise for the > student. > > > > Cheers, > > Tim > >
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X-Google-Language: ENGLISH,ASCII X-Google-Thread: 113943,1ce6d343c70357ac X-Google-Attributes: gid113943,public X-Google-Thread: 102698,1ce6d343c70357ac X-Google-Attributes: gid102698,public X-Google-Thread: 10f497,1ce6d343c70357ac X-Google-Attributes: gid10f497,public X-Google-Thread: fe1d0,1ce6d343c70357ac X-Google-Attributes: gidfe1d0,public X-Google-ArrivalTime: 2001-06-09 08:30:44 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!newsfeed.google.com!newsfeed.stanford.edu!newsfeed.berkeley.edu!news-hog.berkeley.edu!ucberkeley!uchinews!yellow.newsread.com!netaxs.com!newsread.com!POSTED.newshog.newsread.com!not-for-mail Message-ID: <3B224F2E.1985F84A@bestweb.net> From: Tim Gregg <timgregg@bestweb.net> Organization: GreggSys.com X-Mailer: Mozilla 4.5 [en] (WinNT; I) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: uk.sci.weather,ba.weather,chi.weather,alt.talk.weather Subject: Re: A question for the Meteo Data ??? References: <9fonnh$ru01@imsp212.netvigator.com> <3B21A409.85EF72F3@bestweb.net> <9fsipm$gr625@imsp212.netvigator.com> Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Lines: 57 Date: Sat, 09 Jun 2001 15:30:30 GMT NNTP-Posting-Host: 216.179.1.208 X-Complaints-To: Abuse Role <abuse@bestweb.net>, We Care <abuse@newsread.com> X-Trace: newshog.newsread.com 992100630 216.179.1.208 (Sat, 09 Jun 2001 11:30:30 EDT) NNTP-Posting-Date: Sat, 09 Jun 2001 11:30:30 EDT