According to Genesis, a rainbow was placed in the sky as the sign of God’s covenant after Noah’s flood. Genesis 9:13 describes the rainbow in the cloud as the sign of the covenant between God and the earth.
The covenant follows the flood and includes God’s promise that a flood will not again destroy all life on earth. In the story, the rainbow is therefore a reminder of a promise, not merely a weather observation.
The passage also connects the sign with clouds and rain, making it a recurring visual reminder whenever it appears. The rainbow is sometimes called the “bow” in translations, reflecting the ancient image of a bow set in the clouds. This is separate from the olive leaf brought by the dove, which marks an earlier stage of the narrative.