Where there really no rainbows before the great flood?

The Bible says that until the time of the flood, "there went up a mist from the earth, and watered the whole face of the ground." No rain falling, no refraction from raindrops. It's been suggested that there was a water canopy over the entire earth, making the atmosphere heavier, and giving it a bariatric presence that was the cause of people living for long periods of time. Rain fell, atmosphere got lighter, lifespans got shorter.