Why is the symbol of the covenant a rainbow (Gen 9:13-16)?

The “bow in the cloud” image is repeated three times here. It is explicitly called a “sign,” which is remarkable in that it proves once for all—if proof were really needed—that God does use signs or symbols as memorials used in teaching. Of course, such signs can be found throughout the Bible. It is an appropriate symbol since rainbows generally appear when the rain ends. That we are to look to this as a symbol that God will never again flood the Earth suggests that the rains will always end; if the rainbow will always come out, then the rains will not go on so long as to wipe everyone out again.