Corona sky parameters

hi everyone,
someone can tell me how works the parameter of rawa-fake corona sky? is there any guide or tutorial on the internet?
i search everywhere but i found nothing

thanks to all

I would suggest just using Hosek&Wilkie model. It is the most realistic and reliable one.
The others can be just tuned by changing the available parameters. You can use IR for this to get good feedback.

thank you!! i already think this and you conferm!!