aridity vs aridness

aridity and aridness both are nouns.

Word	Noun	Adjective	Verb	Adverb
aridity	Yes	No	No	No
aridness	Yes	No	No	No

As nouns, aridity and aridness are synonyms defined as:

aridity and aridness: a deficiency of moisture (especially when resulting from a permanent absence of rainfall)

Other synonyms of aridity include thirstiness.

aridity (noun)	aridness (noun)
the quality of yielding nothing of value	a deficiency of moisture (especially when resulting from a permanent absence of rainfall)
a deficiency of moisture (especially when resulting from a permanent absence of rainfall)