The azimuth angle is the compass direction from which the sunlight is coming. At solar noon, the sun is always directly south in the northern hemisphere and directly north in the southern hemisphere. The azimuth angle varies throughout the day as shown in the animation below. At the equinoxes, the sun rises directly east and sets directly west regardless of the latitude, thus making the azimuth angles 90° at sunrise and 270° at sunset. In general however, the azimuth angle varies with the latitude and time of year and the full equations to calculate the sun's position throughout the day are given on the following page.
The azimuth angle is like a compass direction with North = 0° and South = 180°. Other authors use a variety of slightly different definitions (i.e., angles of ± 180° and South = 0°).
The azimuth is calculated from the above parameters:
where α is the elevation
The above equation only gives the correct azimuth in the solar morning so that:
Azimuth = Azi, for LST <12 or HRA < 0
Azimuth = 360° - Azi, for LST > 12 or HRA >0