This paper presents various correlations of the hourly clearness index K-t with the hourly diffuse fraction K-d on a horizontal surface for Amman/Jordan. The first correlation is based on Orgill and Hollands method, but using weighted averages. The second correlation is based on hourly integrated values of K-t＇s and K-d＇s without any grouping. A refinement of the latter correlation is attempted by including a random shock.