Re: Precession

From: Carsten Troelsgaard (carsten.troelsgaard_at_mail.dk)
Date: 10/31/04 

Date: Sun, 31 Oct 2004 15:58:12 +0100

"don findlay" <don@tower.net.au> skrev i en meddelelse
news:5f164087.0410301429.54ad1b2c@posting.google.com...
> bobg@radix.net (Robert Grumbine) wrote in message news:<cljl8g$a8r$1@news1.radix.net>...
> > In article <417c330a$0$65542$edfadb0f@dread15.news.tele.dk>,
> > Carsten Troelsgaard <carsten.troelsgaard@mail.dk> wrote:
> > >
> > [snip others, and rewrap Carsten's lines to ca. 70 characters,
> > versus the alternating 70/30 he's got]
> >
> > >To be frank, I never gave 'black holes' or other astronomical
> > >considerations much attention... except for handier problems like
> > >precession. Precession seems to be 'within my reach' though my book
> > >of physics says, that the Earth precesses a whole revolution in
> > >26.000 years - I find it somewhat difficult to believe that the
> > >Earth's spin-axis at part of this time is lying in the plane of the
> > >Sun-Earth rotational plane and thus effectively give no intermediate
> > >seasons through the year (or rather half a year day/night for pole
> > >positions). I probably better get used to the idea - unless someone
> > >can correct my physics. Intuitively this must have a measurable effect
> > >on global circulation and weatherpatterns. Having revealed my ignorance
> > >this way, I figure that I shouldn't apply for a job on calculations
> > >of global warming.
> >
> > Stuart (Bigdakine) already addressed part of this.
> >
> > The torque calculations aren't that difficult to do. Just
> > take the earth as an oblate spheroid with flattening of ca. 1/300.
> > (It's a bit larger than that, but close enough for hand work.)
> > You know the size and moment of inertia of the earth, then apply
> > the torques for the 5 degree off-equatorial motion of the moon, and
> > the 23.5 degrees offset between the earth's equator and its
> > orbital plane around the sun. See also, for instance,
> > Milankovitch's 1941 book on the ice ages, or recent (last
> > 25 years series) papers by Andre Berger.
> >
> > The precession is indeed considered to affect climate, on its
> > time scale. The precession alters the relation between the timing
> > of perihelion and of northern hemisphere winter. Right now,
> > NH winter (Dec 21) is near perihelion (Jan 3).
>
> Yeah, Carsten, ...look whose torquing, ... Bill and Ben, ..the two
> gyrating- twisting, johnny-come-lately flowerpot men, ...the ones
> intent on mussin' up my petunia patch, by denying the importance of
> the Earth's rotation - sorry, ..the Earth's *variable* rotation

No, noone are denying/defending the ability of the spinning Earth to leave an imprint, but since you
appear to be oblivious to the fact that you rest some argumentation on it's presence, it's
surpricing that you oppose a discussion of an achtual calculation of it. You have neither delivered
the calculation nor conveyed a belief that you even understand a connection between spin and
structure. It has nothing to do with an expanding earth, but if you want to take it into account you
could do the credability of your general idea a favour by presenting the physics yourself or a
reference to someone that can. I obviously missed it as a general and accepted state of affairs.

> (says
> Oriel) - in its geological history. So you reckon it shows up in the
> fine detail of the growth in the record of the weather in the
> stratigraphic sequence, but not in the growth of the ocean floors that
> accompany it? You're betting a feather against the gargantuan
> blunderbuss of a juggernaut, and that pair are diddling their smelly
> little arithmetic to 'prove' it (...cribbing from their swindlesheets
> insteading of looking in the Good News Book:-
> <http://users.indigo.net.au/don> Touting 'ccreation instead of
> creation? Hah, -. What a laugh. Who's listening to them? You?
> What have *You* got to say, ... (fronting up here in your good suit)?