Dear John, At last! Congratulations! You go to the top of the class and put all those youngsters to shame!!
> ... a north-facing wall on the > Arctic Circle at the summer > solstice, or a south-facing wall > on the Antarctic circle at the > summer solstice down under. The analysis is easy... When sun is due east (or due west) its hour-angle H is given by: cos(H) = -tan(dec)/tan(latitude) Here H is hour-angle since midnight. [Some obvious constraints apply; the sun is rarely due east on the equator for example.] At the summer solstice on the arctic circle H = 100.83 degrees or 6.72 hr. Accordingly, the north side of the wall gets twice this, or 13.44 hours of sun, in a 24-hour period. No tricks or other sleights of hand are needed! You all still have four days left to go to the arctic circle to check this! Frank --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
