In Genesis, God placed a rainbow in the clouds after Noah’s Ark and the Flood as a sign of the covenant.
Genesis 9 describes God’s covenant with Noah, his descendants, and every living creature that the earth would not again be destroyed by a flood of that kind. The rainbow appears in the clouds as the visible reminder of that promise.
The sign is presented after Noah leaves the Ark and builds an altar. Genesis uses the Hebrew term qeshet, commonly translated as “bow,” linking the image to a bow set in the clouds. English translations generally render it as “rainbow,” the familiar term used in this story.
This rainbow is different from the dove Noah sent from the Ark. The dove is part of the search for dry land in Genesis 8, while the rainbow belongs to the covenant scene in Genesis 9. The passage does not say that rainbows first began to exist then; it assigns them symbolic meaning.