Darkness surrounds him

Clouds and total darkness surround him; righteousness and justice are the foundation of his throne.
-Psalm 97:2

What does it mean that darkness surrounds him?  Here are some notes:

"The writer of this psalm also saw the Lord coming to rule and reign on the earth. He exhorted his readers to prepare for that event by living appropriately in the present.

These verses reveal the appearance of the Lord in terms similar to other visions God gave His prophets (cf. Isa. 6:1-4; Ezek. 1; Rev. 1). The psalmist’s words describe God’s glory in figurative language. Clouds and thick darkness picture awesome power (cf. Deut. 4:11; 5:22-23; cf. Zech. 14:6-7). "

-Thomas L. Constable (Constable's Notes)

"Clouds and darkness are round about him." The figurative language in the poetical parts of the Old Testament is frequently taken from the historical books, and refers to the facts therein recorded; thus the appearances of God to the saints and patriarchs in old times is the origin of the figure in our text. If you look at the history of these appearances, you will find they were all accompanied with clouds and darkness. The cloud of the Lord went before the children of Israel when they departed from the land of bondage. This cloud had a dark and bright side, and was a symbol of the divine presence. Thus it preceded the people in all their marches, as a pillar of fire by night, and of a cloud by day. When Solomon dedicated the temple, the glory of the Lord filled the house, and the priest could not enter into the house of the Lord, because the glory of the Lord filled the house. When God descended upon Mount Sinai, "there were thunders and lightnings, and a thick cloud upon the mount, and the voice of the trumpet exceeding loud. And Mount Sinai was altogether on a smoke, because the Lord descended upon it in fire; and the smoke thereof ascended as the smoke of a furnace, and the whole mount quaked greatly. And the Lord came down upon Mount Sinai, upon the top of the mount" (Exodus 19:16, Exodus 19:18, Exodus 19:20). When our Saviour was transfigured before three of his disciples, "a bright cloud overshadowed them," from which proceeded the voice of the Father, saying, "This is my beloved Son, in whom I am well pleased; hear ye him." And Peter, who was present there, afterwards referring to the fact, says that the voice proceeded "from the excellent glory." Thus, in all the symbols of the divine presence, there was a mixture of splendour with darkness and obscurity. So it is in the operations of Providence: in a moral and figurative sense, we may say that clouds and darkness surround all the operations of divine power and wisdom.

Clouds are emblems of obscurity; darkness, of distress. The works of God's providence are often obscure and productive of distress to mankind, though righteousness and judgment are the habitation of his throne. 

- Robert Hall

"Clouds and darkness are round about him." God doth govern the world mysteriously. As there are mysteries in the word, so in the works of God; δυσνόητά "things hard to be understood," (2 Peter 3:16,) many riddles which nonplus and puzzle men of the largest and most piercing intellectuals: "Behold, I go forward, but he is not there; and backward, but I cannot perceive him; on the left hand, where he doth work, but I cannot behold him: he hideth himself on the right hand, that I cannot see him: but he knoweth the way that I take." Job 23:8-10. God knoweth our ways, and counteth our steps; but the wisest of men do not know all God's ways. His way is frequently in the sea, and his chariot in the clouds; so that he is invisible, not only in his essence, but also in the design and tendence of his operations. Those that behold him with an eye of faith, do not yet see him with an eye of understanding, so as to discern his way, and whither he is going. Paul assures us, "His judgments are unsearchable, and his ways past finding out." Romans 11:33. Some of them, indeed, are obvious, plain, and easy; we may upon the first view give a satisfactory account of them; we may read righteousness, equity, mercy, goodness, love, in them, because written in capital letters, and with such beams of light as he that runs may read them. But others of God's ways are dark and obscure, so that they are out of our reach and above our sight. He that goes about in them to trace God, may quickly lose himself. They are like that hand-writing upon the wall, which none of Belshazzar's wise men could read or give the interpretation of (Daniel 5:8). There are arcana imperii, "secrets of state and government," which are not fit to be made common. But this may be our comfort: - though God doth not now give any account of his matters, nor is he obliged thereunto, yet he can give a very good and satisfactory account; and one day his people shall be led into the mystery; and, though many things which God doeth they know not now, yet they shall know them afterward; and when they know, they shall approve and admire both the things, and the reason, and the end. They shall then be perfectly reconciled to all providences, and see that all were worthy of God, and that in all he acted θεοπρεπῶς, "as did highly become himself." 

- Samuel Slater (1704) in "The Morning Exercises."

How despicable soever Christ's kingdom may seem to the world, yet it is full of heavenly majesty, "clouds and darkness are round about him." The glory of Christ's kingdom is unsearchable, and hid from the eyes of the world, who cannot take up the things of God, except he reveal himself to them, and do open the eyes of the understanding: "clouds and darkness are round about him." 

- David Dickson

"Darkness." Psalm 97:1-5 have a striking resemblance to the awful pomp of the march of God, as described Psalm 18:8, Psalm 18:9, and Psalm 68:8. All the dread phenomena and meteoric array of nature are in attendance; thunder and lightning, and earthquakes and volcanoes, with streams of melting lava, like streams of melting wax. Yet all is justice and equity, joy, exultation, and glory; and the wicked alone - the adversaries of Jehovah feel his judgments - the host of idols and their brutish worshippers. 

- John Mason Good

From The Treasury of David by Charles H. Spurgeon (1885)