Set the fraction of the horizontal sky area which is covered by clouds.
ic_cloudcover value
When a cloud cover is specified, the result will be calculated by
the independent pixel approximation (IPA), that is, as weighted average
of cloudless sky and overcast sky, where the cloud properties are taken
from ic_file, etc. Please note that, if both wc_cloudcover and
ic_cloudcover are set, both must be equal.
This option is ignored, if the option cloud_fraction_file is used.