A general illuminance model for daylight availability

Noting the below observations, it appears possible to avail ourselves of much of the useful research done in the past to aid us in developing a generic model for daylight availability across North America. Much can be learned of a general nature by reviewing the sky illuminance measurement of others, but to make this wealth of information useful for our particular interest in North American skies, which is our objective here, extensive sky measurement must be initiated for several strategic sites in the United States and Canada. Those made In this country need to be updated and new measurements need to be made.