Hey Stephan (and Sylvia),
First of all, be careful, the solar analemma is
anything but symmetric! It has a larger lobe in the
southern hemisphere and is not symmetric about the
celestial equator. It's shape is a mixed of two
signals; one defined by the Earth's tilt and one
defined by the Earth's eccentricity about the Sun. But
that said it's *shape* does not dictate *length of
day* per se, only how soon the sun will rise or set
with respect to a "mean sun" and the declination of
the sun. Great explanation at:
http://www.analemma.com
Does your definition of "daylight" include
different forms of twilight (civil, nautical, or
astronomical)? If so, than (without any mathematical
reasoning) I would argue that the Arctic Cirles get
the most light!
Regards,
Jeff Umbarger
Plano, TX USA
--- Stephan Szyman <szymanss@hotmail.com> wrote:
> hi there, sylvie,
>
> great question!
>
> at first, I was leaning toward answering that the
> further one goes from the
> tropics, the fewer minutes per year of daylight one
> will experience, but
> this proved false. in their summer each polar region
> stays in sunlight 24
> hours per day during the period near solstice (and
> conversely, in darkness
> during the winter.)
>
> if you look at an analemma (when centered on the
> equator) you will see that
> it is symmetrical, and visually represents the
> balance we are wondering
> about, the average amount of daylight hours for a
> given location on the
> earth's surface (disregarding, of course,
> topographical and other
> obstacles! it is important to remember the earth is
> far from being a perfect
> sphere.)
>
> I came to the conclusion that yes, for any given
> location on the earth's
> surface, the average hours of sunlight or daylight
> annualy would be
> "roughly" the same. just to be on the safe side, I
> called a retired
> physicist I know (the directory of the society's
> observatory;) even he
> seemed stumped for a few minutes, but he told me
> that he believed my
> analysis to be correct.
>
> I will forward this question to my greatest resource
> in these matters, the
> seesat-L emailing-list.
>
> cheers!
>
> -stephan
>
>
> >Hey Stephan,
> >
> >I have a question for you and I think you are
> probably the only person
> >that I know who can answer it.
> >
> >Last night I was talking to a friend and we were
> wondering whether the
> >average amount of daylight hours that any given
> location on the earth
> >gets over the course of the year would be the same.
> >
> >Any thoughts?
> >
> >Hope all is well,
> >Sylvie
>
>
>
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