I'm afraid Dan Uza's proposal is a non-starter. The colour temperature of daylight fluctuates, depending on the weather. Even on a cloudless day it is obvious that the colour of the sky varies from point to point. The colour temperature is low near the horizon and highest in the direction facing away from the sun and at an altitude roughly equal to (90 degrees minus the solar altitude). These patterns are clearly visible to the naked eye. John Lynes
On 29 August 2016 at 13:37, Dan-George Uza <[email protected]> wrote: > Hello! > > I've recently become interested in film photography. I think it has some > similarities to sundials. For example, it is said that black and white film > photography is about taking pictures not of actual subjects, but of light > and shadows. I find it fascinating how light actually darkens the salts on > the photographic material, like a gnomon does to the surface of a sundial. > Not to mention the meridian lines in churches that also act like giant > camera obscuras, projecting the solar disc image onto the pavement. > > Now I've read that daylight color temperature fluctuates by the hour of > the day: light in the early morning and late evening has under 5000 K, > while around noon it reaches 6000 K and beyond . But can you actually use > this intrinsic light quality for time telling i.e. design a color > temperature sundial? > > Dan Uza > Romania > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > >
--------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
