This verse, together with the next verse, describes how David asks the Lord to deal with what is happening on earth. David starts by asking if the Lord will bend open (or move over) the heavens (perhaps in the sense of a sky dome), so that the road is free for him to descend from heaven. When he then touches the mountains, they will smoke, as in olden days at Mount Horeb. This signifies God’s power. This could also make one think of volcanoes.
5 Bow your heavens, O LORD, and come down! Touch the mountains so that they smoke!