According to Genesis, God set a rainbow in the clouds as the sign of the covenant after Noah's Ark.
Genesis 9:12–17 describes the covenant made after Noah, his family, and the animals left the Ark. God says the rainbow will appear in the clouds as a reminder of the covenant between God, Noah, every living creature, and the earth. The passage connects the sign with a promise that a flood would not again destroy all flesh.
The rainbow is therefore not simply a weather detail in the story. It functions as a visible covenant sign and is presented as a reminder for both God and humanity within the narrative. Genesis calls it “my bow,” using the same word that can mean a bow used as a weapon.
Modern readers often associate rainbows with many symbolic meanings, but the specific post-Flood meaning in Genesis is the covenant promise. The text does not say that rainbows first appeared only after the Flood; it gives them a new covenant role.