> >> ----- Original Message ----- > > > From: Roger Bailey <[EMAIL PROTECTED]> > >> To: <[EMAIL PROTECTED]>; <[email protected]> > >> Sent: Saturday, September 11, 1999 6:50 PM > >> Subject: Re: Formula to calculate sunrise > > > >> The easy, elegant formulae that you can use to determine sun rise and set > >> phenomena are: > >> > >> Sunrise time t: Cos t = Tan L x Tan D > >> Sunrise location: Cos Z = Sin D / Cos L > >> Sunrise Path: Cos psi = Sin l / Cos D > > > >
To all, Some messages have been on this list about the formula to calculate sunrise and so on. The first one ( Cos t = Tan L x Tan D ) in fact calculates the length of half the day arc. But in that formula must be a negative sign, thus the formula is : Cos t = - Tan L x Tan D Best, Fer. -- Fer J. de Vries [EMAIL PROTECTED] http://www.iaehv.nl/users/ferdv/ lat. 51:30 N long. 5:30 E
