OK, I would also like to take a turn and ask a question to the mathematically inclined:
I have been trying to figure out how to plot the duration of daylight over the course of the year as a function of latitude. (I would generate a curve for each latitude I am interested in.) I believe the result should be a sine curve which looks comparatively flat at the equator, growing increasingly steeper until the polar circle, where it would turn into a binary step curve and the six month day turns to six month night -- leaving aside physical effects like refraction. I am particularly interested in the slope of the curve around the equinoxes at northern latitudes, when the transition from long summer days to short winter days is quite abrupt. Jack Aubert -----Original Message----- From: sundial [mailto:[email protected]] On Behalf Of John Goodman Sent: Sunday, February 01, 2015 12:37 PM To: Sundial List Subject: Re: A question for the mathematically inclined Thanks to everyone who replied with suggestions, both on and off the list. When I asked my question, I assumed there was a trivial solution that could be simply explained. I realize now that the calculations are not straightforward. Roger Bailey has given me an approach that I believe will work for me. I’m now trying to understand how the math represents the spatial geometry of the problem. The variety of solutions I received are an indication of the broad experience and wisdom embodied in this group. I'm always grateful for that asset. > On Jan 31, 2015, at 10:05 AM, John Goodman <[email protected]> wrote: > > Dear dialists, > > Does anyone know a formula for calculating the hour angle given the azimuth, > declination, and latitude? > > I’d like to know the time of day, throughout the year, when the sun will be > positioned at a particular angle. This will allow me to determine when > sunshine will stream squarely through a window on any (sunny) day. > > I’ve seen several formulae for calculating azimuth. I suspect that one of > them could be rewritten to solve for the hour angle given the azimuth instead > of the finding the azimuth using the hour angle (plus the declination and > latitude). Unfortunately, I don’t have the math skills for this conversion. > > Thanks for any suggestions. --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
