[Radiance-general] the disk of the sun

[Michael Martinez]

Hi All - 

I'm working on a project in which the brightness of the disk of the sun has become a discussion topic. 

Using gendaylit set for California's central valley, a view toward clear (smoggy-ish) sunny skies  at 8am on September 1 reveals a disk luminance of 987,365,074 cd/m2. 

This seems perfectly reasonable, although when I find myself commenting "oh yes, it's about a billion..." I can't help but pause. 

Does anyone know of a handy reference for disk luminance based on location and climate? Or better yet, anyone out there with greater math skills than I know how to derive disk luminance from direct normal radiation found in a weather file? 

Thanks! 

Mike