Cldfra and Swdown relationship

[Capivarus]

Hello everybody!!!

The subject, where I can find the relationship between Cldfrac and Swdown wrf variables??? Physically is clearly, but the apparently qualitative nature of cldfra and it's impact on swdwn is something I want to know!!! Any idea?? Thank you!!!

 

[jimenez]

you can think as if the final GHI is a weighted mean of the clear sky and cloudy sky GHI where the weight is the cloud fraction.

 

[shaildph]

you can think as if the final GHI is a weighted mean of the clear sky and cloudy sky GHI where the weight is the cloud fraction.

Can you clarify it a little bit, as cloud fraction is one, and there should be more weights? I would really appreciate if you may please answer it detail. This would be very helpful. Thank you in advance!