Oops, a typo: I meant to say that, at the North Pole, no sundial will tell time when the solar declination is south. But, of course, at the South Pole, it's when the solar declination is *north*, that there won't be sunshine and sundials won't tell time.
Michael Ossipoff On Mon, Nov 16, 2015 at 1:25 PM, Michael Ossipoff <email9648...@gmail.com> wrote: > People who have already replied have said pretty much everything that I'd > have said. > > As several people pointed out, yes the shadow-casting gnomon-edge should > be tipped 32 degrees above the horizonal, at latitude 32 south. > > But, because it's south latitude, the up-pointing end of the gnomon should > point southward, as was also pointed out. ...and the hour-marking should > be anti-clockwise instead of clockwise, because the sun goes around the sky > anti-clockwise in the Southern Hemisphere. > > Of course the reason why your analog clocks and watches have clockwise > dials is because the sun goes around clockwise in the Northern Hemisphere. > > Someone pointed out that an Equatorial Band Sundial works fine at or near > the equator. A Horizontal Flat Dial also works at the equator. But it takes > the form of a Polar Dial, and, because it's a Polar Dial, its range of > timetelling hour is limited. > > A Horizontal Flat Dial would work fine at the North Pole or South Pole. > There, it would be an Equatorial-Dial. But it wouldn't tell time in winter > (more accurately, any time when the declination is south). ...but there > wouldn't be sunlight there, when declination is south, anyway, and so no > sundial would tell time then. > > Michael Ossipoff > 26N, 80W > > On Sun, Nov 15, 2015 at 5:37 PM, Phil Dorman <p...@wattagan.com> wrote: > >> Hi Everyone, >> >> >> >> I joined this list because I have a specific question which I can’t find >> a definitive answer to. >> >> >> >> I want to install a sundial at Perth WA Australia which is pretty close >> to 32deg South latitude. >> >> From what I can determine that means the Gnomon should be 32deg above >> horizontal. >> >> Or is that just for the Northern Hemisphere ?? >> >> >> >> As I move North in Australia the Latitude number gets Smaller >> >> Eg Latitude of Brisbane QLD (further North) is 27.46deg >> >> So presumably the Latitude at the Equator would be Zero ! >> >> Which would mean a sundial Gnomon at the Equator would be Horizontal ie >> Flat on the Ground >> >> Which of course would not work. >> >> And at the South Pole it would be Vertical 90deg from Horizontal and also >> would not work since there would be no ground for the shadow to fall on. >> >> >> >> So. Am I correct to put it at 32deg from Horizontal for Perth WA or not ? >> >> >> >> Phil Dorman /:~)> >> >> [image: MAATES_Transparent_for_email] <http://www.maates.com/> >> >> >> *Machinery Appreciation & Transport Engineering Society*946 Wattagan Crk >> Rd >> Watagan NSW 2325 >> >> 0419 501285 >> >> >> >> >> >> --------------------------------------------------- >> https://lists.uni-koeln.de/mailman/listinfo/sundial >> >> >> >
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