Solar zenith angle
Solar zenith angle From Wikipedia, the free encyclopedia: [https://en.wikipedia.org/wiki/Solar_zenith_angle] The solar zenith angle is the angle between the zenith and the centre of the sun's disc. The solar elevation angle is the altitude of the sun, the angle between the horizon and the centre of the sun's disc. Since these two angles are complementary, the cosine of either one of them equals the sine of the other. They can both be calculated with the same formula, using results from spherical trigonometry.