Tafsir of Ar-Rum 30:48

(Allah is the One Who sends the winds)—This is a new beginning introduced to explain what was summarized previously regarding the states of the winds—(so they stir up clouds)—meaning He moves them and spreads them, unfolding them completely and continuously at times—(in the sky)—meaning in its direction and path, not within the sky itself in the immediate literal sense—(as He wills)—moving or stationary, layered or otherwise, covering one side rather than another, and so on. Thus, the descriptive sentence acts as a circumstantial qualifier through interpretation.

(And He makes them into fragments)—meaning into pieces at other times. Ibn Amir read it with a quiescent sin (letter ‘s’), either as a lightened form of the vowelized version, or as the plural of kis-fah (a piece), or as an infinitive like ‘ilm (knowledge) used as an adjective for intensification, or interpreted as a passive participle, or with the implication of "possessing fragments."

(So you see)—O you who are capable of vision—(the rain)—meaning the downpour—(emerging from within them)—meaning from their fissures. This is the plural of khalal (gap). This applies to both states: the continuous and the fragmented. The pronoun refers to the clouds (sahab), which is a collective noun that may be treated as masculine or feminine. Regarding the reading of kisa-fan with a quiescent sin, it was suggested that the pronoun refers to it (the kis-f), but that is of no consequence.

(And when He causes it to fall upon whom He wills of His servants)—meaning upon their lands and territories. The letter ba in bihi (with it) is for transitive purposes—(they immediately rejoice)—meaning they are surprised by the joy of the arrival of fertility.