Answers to Questions by Yair Davidiy (11 December 2017, 23 Kislev, 5778)
https://www.quora.com/Were-there-rainbows-before-the-great-flood/answer/Yair-Davidiy
See: Ten Spectacular Rainbows over Israel 10 spectacular rainbows over Israel
Rainbows are explained as raindrops having a prism like effect on light.
The Bible indicates that the atmosphere was different before the flood.
There were waters above the earth and waters beneath it (Genesis 1:6).
The release of these waters is the agency that caused the Deluge to happen.
Genesis (NASB) 7:
10 It came about after the seven days, that the water of the flood came upon the earth. 11 In the six hundredth year of Noah's life, in the second month, on the seventeenth day of the month, on the same day all the fountains of the great deep burst open, and the floodgates of the sky were opened. 12 The rain fell upon the earth for forty days and forty nights.
People were different they lived longer.
Geologists finds traces of dinosaurs and after them of gigantic mammals. They date from before the Flood. Such beasts could not survive in the present environment.
There would not be enough food for them. Their very weight could be a problem. Ergo the atmosphere must have been different.
If the atmosphere was not the same as it is today then the effect of light on raindrops may not have been the same as it now is.
Rainbows may not have existed.
Where is the problem?
After the flood the atmosphere had changed. The Rainbow is proof that the waters that once existed above and below flooded the earth.
Genesis (NASB) 6:
12 God said, 'This is the sign of the covenant which I am making between Me and you and every living creature that is with you, for all successive generations; 13 I set My bow in the cloud, and it shall be for a sign of a covenant between Me and the earth. 14 It shall come about, when I bring a cloud over the earth, that the bow will be seen in the cloud, 15 and I will remember My covenant, which is between Me and you and every living creature of all flesh; and never again shall the water become a flood to destroy all flesh. 16 When the bow is in the cloud, then I will look upon it, to remember the everlasting covenant between God and every living creature of all flesh that is on the earth.' 17 And God said to Noah, 'This is the sign of the covenant which I have established between Me and all flesh that is on the earth.'