Charles H. Spurgeon on Psalms 104:4

Who maketh his angels spirits. Some render it, Who maketh his angels as the winds, to which they may be compared for their invisibility, they being not to be seen, no more than the wind, unless when they assume an external form; and for their penetration through bodies in a very surprising manner; see Ac 7:6-10; and for their great force and power, being mighty angels, and said to excel in strength, Ps 103:20; and for their swiftness in obeying the divine commands; so the Targum, "He maketh his messengers, or angels, swift as the wind." —John Gill.