On the characteristic distribution of hourly diffuse and global solar radiation at Ibadan

✍ Scribed by F.J.K. Ideriah

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 498 KB
• Volume: 2
• Category: Article
• ISSN: 0960-1481
• DOI: 10.1016/0960-1481(92)90081-d

✦ Synopsis

The potential of a previous model for calculating direct and diffuse solar radiation is further explored by employing the model to study the characteristic distribution of hourly insolation for six years (1980)(1981)(1982)(1983)(1984)(1985) at lbadan. The study covers "clear" and "moderately clear" sky conditions for which the turbidity ~ < 0.175, and for which the range of fl, the probability of occurrence in the year is 60.63%. The computed results yield correlations of the hourly daily insolation ratios rh and r~ with the sunset hour angle 0~ which are in satisfactory agreement with, and therefore confirm, the work of Liu and Jordan as well as Collares-Pereira and Rabl. The present results also show that the hourly diffuse ratio k~ is a function of both the hourly clearness index kx and time t from solar noon : this explains why the previous plot of Orgill and Hollands of k~ vs kx without accounting for time effect gives an unacceptably wide scatter. Further, the present correlation of the hourly diffuse coefficient kd with kT yields similar trends to those found in the previous work of Iqbal.