Yes, down like a lurid rainbow Zeus sends arching
down to mortal men from the high skies, a sign of war
or blizzard to freeze the summer’s warmth and put a halt
to men’s work on the face of the earth and harry flocks –
so shrouded round in a lurid cloud came Pallas now
and dove in the Argive ranks to fire up each man.

– Homer

The Iliad, Book 17, lines 624-629. Goddess Athena moves to fire up and encourage the Achaean soldiers in battle. In Homer’s epic simile, she is said to descend from heaven like the colored rainbow Zeus sends as a sign of war or blizzard.