Emblem for Cum severitate lenitas (Even in harshness there is mercy) represented by a storm cloud and a rainbow, from a book of emblems by Henry Peacham, ca. 1610.
Featured on PDR in the collection Rainbows in Art
Or, since that hope denied in worlds of strife,
Be thou the rainbow in the storms of life!
The evening beam that smiles the clouds away,
and tints tomorrow with prophetic ray!
(Lord Byron, The Bride of Abydos)