cloud cover vs cloudiness

cloud cover and cloudiness both are nouns.

Word	Noun	Adjective	Verb	Adverb
cloud cover	Yes	No	No	No
cloudiness	Yes	No	No	No

As nouns, cloud cover and cloudiness are synonyms defined as:

cloud cover and cloudiness: the state of the sky when it is covered by clouds

Other synonyms of cloud cover include overcast.

cloud cover (noun)	cloudiness (noun)
the state of the sky when it is covered by clouds	the quality of being cloudy
	the state of the sky when it is covered by clouds
	gloomy semidarkness caused by cloud cover