What sign did God set in the sky after the Flood in Genesis?

After the Flood, God set a rainbow in the clouds as the sign of the covenant with Noah. Genesis 9 presents the rainbow as a reminder of God’s promise not to destroy all life on earth with another flood.

The covenant extends beyond Noah and his immediate family. Genesis describes it as applying to every living creature and to the earth itself. The rainbow therefore functions in the story as a visible sign of a universal promise, not merely as a private message to one person.

Rainbows are optical phenomena produced when light is refracted, reflected, and dispersed by water droplets. Genesis uses the familiar natural phenomenon within its theological narrative. The rainbow’s later association with peace, hope, and reconciliation comes partly from this biblical covenant imagery, although the text specifically emphasizes the promise concerning future floods.