Overview
The solar zenith angle is the zenith angle of the Sun, i.e., the angle between the sun’s rays and the vertical direction. It is the complement to the solar altitude or solar elevation, which is the altitude angle or elevation angle between the Sun’s rays and a horizontal plane. Near solar noon, the zenith angle is at a minimum and is equal to the absolute value of latitude minus solar declination angle. This is the basis by which ancient mariners navigated the oceans.