Hour Angle

The hour angle (omega) is the angle through which the earth must rotate to bring the meridian of a point directly in line which the sun's rays.

           Since earth completes one rotation in 24 hours. Therefore, hour angle is equivalent to 15° per hour. When the sun's rays are un line which the local meridian, I.e. at solar noon the hour angle is zero. It us +ve in the afternoon and -ve in the forenoon.

         It can be calculated as,

   

    Omega= [Solar time―12:00] (in hours) ×                                      15 degrees