Sun declination and distribution of solar resources on Earth

Abstract

Abstract The daily path of the Sun across longitude yields night and day, but the Sun also travels across latitude, on a belt 47° wide. The budget of solar resources that the sunrays supply to a location depends on the angle at which they land. The sun meridian declination, along with its velocity and acceleration, as well as the latitudinal distribution of the solar resources, were assessed in terms of beam radiation. The analysis is founded on the geometric model of solar declination. The functions describing the declination, velocity, and acceleration of the apparent Sun resemble one another when plotted against time. Whereas, the functions of declination vs velocity and velocity vs acceleration approach a circle. One third of the beam radiation that the Sun delivers to the Earth along the year, halves between two latitudinal belts 3.5° wide, next to the tropics of Cancer and Capricorn. Surprisingly, the belt 0 to 20° harvests a budget similar to that of two belts 20 to 23.5° (33%). The distribution of beam radiation follows the same pattern in either hemisphere. All sites whose latitude converge, whether within or between hemispheres, accumulate an equivalent budget of solar heat and light from beam radiation.