Jamieson, Fausset and Brown on Job 36:27-28

27-28. The marvellous formation of rain (so Job 5:9, 10).

maketh small--Rather, "He draweth (up) to Him, He attracts (from the earth below) the drops of water; they (the drops of water) pour down rain, (which is) His vapor." "Vapor" is in apposition with "rain," marking the way in which rain is formed; namely, from the vapor drawn up by God into the air and then condensed into drops, which fall (Psa 147:8). The suspension of such a mass of water, and its descent not in a deluge, but in drops of vapory rain, are the marvel. The selection of this particular illustration of God's greatness forms a fit prelude to the storm in which God appears (Job 40:1).