Re: Re: VMs: Analysis of f67v2

[Greg Stachowski <greg@xxxxxxxxxxxxxxxxxxxxxx>]

Hello, Jan, Larry, Pamela!

On Sat, 22 Jan 2005, jan wrote:

> SE to SW is
> only 90  degrees in my book,

Hmm, not sure where my earlier mail to the list went, nobody seems to have 
noticed it ;)

Anyway, as Elmar has correctly pointed out, the sun rises and sets
symmetrically relative to _true_ north and a flat horizon. If the
positions are measured relative to _magnetic_ north then the symmetry will
not occur, as the direction of the magnetic pole is offset from true
north, in some places by as much as 25 degree.

Also, the angle between the positions at which the sun sets need not be
180 degrees, depending on latitude and season; in winter the angle will be
much less. For example, for Prague the minimum angle is only 103 degrees 
(in late December).

Theres a good explanation, tutorial and calculator at:

http://www.locationworks.com/sunrise/tutor.html
http://www.locationworks.com/sunrise/instruct/
http://www.locationworks.com/sunrise/ssr.html

Cheers,

Greg
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