Gregory the Dialogist

That it should rain upon the earth without man, in the desert, where no mortal dwelleth. To rain upon the earth without man in the desert, is to preach the word of God to the Gentile world. For whilst it retained no worship of the Godhead, and shewed in itself no appearance of good works, it was plainly a desert. And because there was therein no lawgiver, nor any one who could seek God in a reasonable way, there was, as it were, 'no man;' and it remained as if occupied by beasts alone, void of men. …

Morals on the Book of Job, Book XXIX ↗

Thomas Aquinas

He adds the reason why the winds set in motion the rain and the clouds when he says, "to rain on the land of an uninhabited desert," which cannot be lived in because of the aridity of the earth. Vapors bearing rain arise especially from humid places, and so if the clouds and rains were not set in motion by the winds it would follow that it would never rain in dry places. It happens that some places are sometimes irrigated by human industry, when the rains cease. …

Commentary on Job ↗