Rashi: This appointee [over the clouds] turns around with many strategies of Hashem to make rain according to Yisrael's merits. If much rain was decreed on Rosh Hashanah, and afterwards Yisrael soured, Hashem sends the decreed amount in places and times that do not help them, and vice-versa.

Sifri Ekev 39 ¹ : Eretz Yisrael has many mountains. Perhaps places that are not exposed do not drink (get rain)! No - He surrounds [the land] with clouds in all directions, so all places will drink.

Ibn Ezra: Hashem turns things. I say that this refers to the Galgal - Hashem turns it with strategies, corresponding to people's actions ² .

Malbim: The rain cycle that Hashem put in nature, always goes around. Rain falls in summer and thunder roars. In winter, the rain turns to snow, and water to ice, via removing the heat from the water. Hashem changes matters to the opposite, based on how He wants to conduct the lower beings, for good or bad.

Rashi: The appointee commands the rain.