נֹגַהּ nogah "brightness" in Amos only at 5:20, it is often in parallel with 'or and is also used metaphorically and especially to describe theophany (2 Sam 22:12=Ps18:12 [both v.13 in Hebrew]) or the human revelation of God (Is 50:10); Ezekiel (10:4) uses nogah to describe God's glory. This may well be the intent in its use to talk of Adonai's Day in Amos.