Sky Distribution Equations 18 Dec, 2018

A number of people have asked me for more information about a comment I made in the CIE Sky app description about using the "latest" sky distribution equations. Basically, whilst trying to work out why the numbers I was getting from my implementation of the CIE Standard General Sky were slightly different to those from other popular daylight tools, I noticed that all of them appeared to be based on code that implemented the original Perez All-Weather Sky equations published in 1993, rather than the CIE Standard General Sky equations from 2003. The differences between the two are relatively small, but certainly enough to confound any direct numerical comparison.