Psalms 18:9

He bowed the heavens also - He seemed to bend down the heavens - to bring them nearer to the earth. “He inclines the canopy of the heavens, as it were, toward the earth; wraps himself in the darkness of night, and shoots forth his arrows; hurls abroad his lightnings, and wings them with speed.” Herder, Spirit of Hebrew Poetry (Marsh), ii. 157. The allusion is still to the tempest, when the clouds ran low; when they seem to sweep along the ground; when it appears as if the heavens were brought nearer to the earth - as if, to use a common expression, “the heavens and earth were coming together.”

And came down - God himself seemed to descend in the fury of the storm.

And darkness was under his feet - A dark cloud; or, the darkness caused by thick clouds. Compare Nahum 1:3, “The Lord hath his way in the whirlwind and in the storm, and the clouds are the dust of his feet.” Deuteronomy 4:11, “the mountain burned ... with thick darkness.” Deuteronomy 5:22, “these words the Lord spake out of the thick darkness.” Psalms 97:2, “clouds and darkness are round about him.” The idea here is that of awful majesty and power, as we are nowhere more forcibly impressed with the idea of majesty and power than in the fury of a storm.