For this, you need the Local Hour Angle
(LHA), which is simply the GHA minus your longitude (for the Western Hemisphere).
and the geometric mean sunrise hour angle
on a horizontal surface, or theoretical sunrise/ sunset [w.
In Figure 10, angle T is the hour angle
measured from the north-south line around the equatorial dial.
The direct radiation is empirical established depending on the extraterrestrial radiation, the medium solar constant, the day number during a year, the distortion factor, the solar altitude angle, the solar declination, the latitude angle, the solar hour angle
, and the local solar time.
The hour angle
h of the moon may be computed from an observed altitude, the known latitude [phi] and an approximate value for the declination "[delta]
To understand these solutions one is required to know basic astronomical nomenclature such as declination, hour angle
, zenith angle, etc.
In reality, Local Mean Time is defined as the hour angle
of the mean Sun, referred to one's local meridian, plus 12 hours.