SEARCH FOR A NEW EMPIRICAL FORMULA FOR THE REPRESENTATION OF THE VARIATION OF THE INTENSITY OF SOLAR RADIATION WITH ZENITH ANGLE

摘要

The author states an empirical formula, relating solar intensity (or solar irradiance) to apparent solar zenith angle, for an observer at arbitrary altitude. The superiority of this formula, especially at large zenith angles, over 3 earlier formulas, is demonstrated by comparison with actual measurements. A procedure is given for quickly approximating the constants in the formula, for a single observer location, from 3 observations at widely different solar zenith angles. To facilitate this procedure, a table of optical air mass and related functions of zenith angle is provided.