The Flood of Noah was a real historical event. Some parts of the Biblical description of the Flood are figurative and other parts are literal. There was literally a Noah, an Ark, and a great Flood. However, the expressions that say the Flood covered all land and killed all animals and humans outside the Ark are a figurative expression of the great extent of this event. Not all species of animals were on the Ark, and it was not 300 cubits long. These expressions are also figurative.
The cause of the great Flood of Noah was a comet striking the deep ocean. This event caused immense tidal waves, threw vast quantities of water into the upper atmosphere, and altered the weather worldwide for many months. It caused torrential rainstorms, and much flooding throughout many areas of the world. This explains not only the Flood of Noah, but the many flood stories from hundreds of cultures in every region of the world.
The rainstorms of the Flood were not like prior and subsequent rains. But I say more. The appearance of the sky after the Flood was not like prior and subsequent times. It was utterly unique and astounding. What Noah saw, what all the survivors saw, was not a simple rainbow on one particular day. They saw a continuing array of atmospheric optical effects, including rainbows of every kind and similar effects. And nothing similar has been seen since that time. The ordinary rainbow after an ordinary rainstorm is a pale reminder of that great set of astonishing optical effects, which occurred after the great Flood.
For when a comet strikes the deep ocean, it casts water into the highest part of the atmosphere, which normally has no water at all. This water exists in a fine mist, at very low temperatures and pressures. In essence, the water thrown that high into the atmosphere would form exceedingly fine ice crystals. The same event would also result in more ice crystals in the upper atmosphere and more water droplets in the lower atmosphere than is usual. (Noah’s Flood: Literal or Figurative?)
What did the rainbow that Noah saw after the Flood look like? If the rainbow that Noah saw after the great Flood were the ordinary rainbow, such as Noah saw many times prior to the Flood, why would he see any significance in that rainbow?
What Noah saw, what all the survivors saw, was not a simple rainbow on one particular day. They saw a continuing array of atmospheric optical effects, including rainbows of every kind and similar effects. And nothing similar has been seen since that time. The ordinary rainbow after an ordinary rainstorm is a pale reminder of that great set of astonishing optical effects, which occurred after the great Flood. The resultant appearance of the sky would be difficult to imagine.
In my opinion, what Noah saw was far more than a simple rainbow. The great Flood was caused by a comet strike in the deep ocean, and this event had a substantial effect on the climate and the atmosphere. As a result, Noah must have seen a series of great atmospheric optical effects, day after day, night after night, month after month, for up to a year or more after he departed from the Ark. He saw a vast array of multiple rainbows on many different occasions: primary and secondary rainbows, reflection rainbows, cloud bows, moon bows, and fog bows. He saw a deeply-reddened sky at sunrise and sunset, and a continually-reddened moon. He saw many different optical effects caused by ice crystals in the upper atmosphere: 22 degree halos, sun dogs, upper and lower tangent arcs, circumzenithal arcs, and various other halos, arcs, and parhelia. And he may well have seen iridescent clouds, mother-of-pearl clouds, ringed glories, and coronae. It is even possible that Noah and the other survivors saw some completely unique optical effects, unknown to modern science, and unknown to any other generation of humanity. For a comet strike in the deep ocean would have had a unique effect on the atmosphere, resulting in extraordinary conditions and extraordinary optical effects.
What Noah saw was a spectacle never before seen by human eyes on the face of the earth, and not seen since even to this very day. He saw multiple optical effects in the same sky at the same time, and different optical effects as the hours and days passed on. He saw more atmospheric optical effects in the first few months of leaving the Ark than any human being of any other generation would see in a lifetime. And this amazing continual display of beauty and splendor reassured him and the other survivors that the terrible event of the great Flood had passed, and their lives could resume. God had blessed them after the punishment of the great Flood.
Much more on this point, about the appearance of the sky after the Flood, is found in my book, Noah’s Flood: Literal or Figurative?, in chapter 8, ‘Noah’s Rainbow’.
See also my previous post:
How should we interpret the story of Noah?