Total radiant properties of materials at the earth’s surface are a function of the condition and type of atmosphere traversed by the sun’s energy. Therefore, the solar irradiation at the earth’s surface has been reexamined using the latest atmospheric data. Based on these calculations a new and expanded set of selected ordinates was calculated. These ordinates are used to evaluate the total solar transmittance, or other properties, for a wide variety of atmospheric conditions, from the spectral data.