Hi, I goofed.
Message text written by Chuck O'Connell > (I think my math is correct, but...) I use : Solar Hour Angle = 18 degrees /sin(23.5) (45.14 degrees HA - 3 hours) and : Solar Hour Angle = 26 degrees /sin(23.5) (65.2 degrees HA - 4:20 ) < The above formulae are clearly wrong. I don't know what I was thinking. Try this instead: HA = 18/sin(90 - yourLatitude + solarDeclination) HA = 26/sin(90 - yourLatitude + solarDeclination) Please let me know if this is correct. <I hate foolish mistakes.> The first gives the hour angle from sunrise (or sunset) when the sun is 18 degrees above the horizon. The second is the hour angle for 26 degrees. When Sol is between these you may see a circumzenithal arc if there are high thin ice clouds. Chuck.
