Another strong angel descends to John with the rainbow around his head (10:1). The previous reference to rainbow said it surrounded the heavenly throne (4:3)
Hence: The angel’s head = the heavenly throne. The angel descends from heaven, but he is gargantuan, able to place a foot in the sea and a foot on land, with his head still in the clouds.
Hence also: The angel’s head = the heavenly throne = the original ark, in the temple that is the “heavenly” Most Holy Place.
Hence also: The angel as a whole is templar, with his cloud-clothing, and his sunny face, with the rainbow crowning his head, and with his fire-pillar feet.