How would you explain a rainbow to someone who has never seen one?

The rainbow is precious. It’s a symbol of what theologians call God’s common grace ,the grace he shows to all people saved and unsaved alike. With the rainbow God promised to restrain his wrath. He promised never again to visit destruction on the earth in the same way. Judgement was delayed, for Noah, his descendants, and for the rest of creation. God would continue to provide rain and sun. He would provide seasons and harvest. Land could be worked, crops could be grown.