Standard Date Periods with Declination Limits

Abstract

A SYSTEM of dividing the year into 16 periods, each denned by certain solar declination values having numerically equal positive and negative magnitudes, has been discussed by me in an earlier paper¹. Research has been continued on the selection of the most suitable declination values and the corresponding dates by examination of ephemerides for the Sun during 1952–64 (ref. 2), resulting in slight modifications of the original selections. Such a system would have many advantages in solar engineering research, where bright Sun conditions are of predominant importance, the computation of solar angles of incidence on variously inclined surfaces being greatly facilitated by the limitation to the five standard numerical declination values shown in the fourth column of Table 1.