re sunrise sunset times in article apr cbis ece drexel edu jpw cbis ece drexel edu joseph wetstein writes hello i am looking for a program or algorithm that can be used to compute sunrise and sunset times here is a computation i did a long time ago that computes the length of the daylight you should be able to convert the information here to sunrise and sunset times rouben rostamian telephone department of mathematics and statistics e mail university of maryland baltimore county bitnet rostamian umbc bitnet baltimore md usa internet rouben math umbc edu definitions z the tilt of the axis of the planet away from the normal to its orbital plane in case of the earth z is about degrees i think i do not recall the exact value in case of uranus z is almost degrees u latitude of the location where the length of the day is measured paris is at about degrees north pole is at a angular position of the planet around the sun as a goes from to degrees the planet makes a full circle around the sun the spring equinox occurs at a l daylight fraction duration of daylight duration of a full day on the equator u l is always near the north pole u degrees l is sometimes one and sometimes zero depending on the time of the year computation define the auxiliary angles p and q by sin p sin a sin z cos q h tan u tan p q degrees conclusion l q if q is measured in degrees l q pi if q is measured in radians wait but what is h the cutoff function h is defined as follows h s s if s if s if s as an interesting exercise plot l versus a the graph will shows how the length of the daylight varies with the time of the year experiment with various choices of latitudes and tilt angles compare the behavior of the function at locations above and below the arctic circle rouben rostamian telephone department of mathematics and statistics e mail university of maryland baltimore county bitnet rostamian umbc bitnet baltimore md usa internet rouben math umbc edu
