The story goes that God provided the rainbow as a symbol of his promise to never again destroy the world by flood.
Noah and his family saw the rainbow after they left the ark. After the waters had receeded. After it had stopped raining for months...
Yet a rainbow is simply sunlight spread out into its spectrum of colors and diverted to the eye of the observer by water droplets.
Yes, a rainbow needs rain to appear.
Read the Biblical account and see for yourself:
(Genesis 8:1-7) After that God remembered Noah and every wild beast and every domestic animal that was with him in the ark, and God caused a wind to pass over the earth, and the waters began to subside. 2 And the springs of the watery deep and the floodgates of the heavens became stopped up, and so the downpour from the heavens was restrained. 3 And the waters began receding from off the earth, progressively receding; and at the end of a hundred and fifty days the waters were lacking. 4 And in the seventh month, on the seventeenth day of the month, the ark came to rest on the mountains of Ararat. 5 And the waters kept on progressively lessening until the tenth month. In the tenth month, on the first of the month, the tops of the mountains appeared. 6 So it occurred that at the end of forty days Noah proceeded to open the window of the ark that he had made. 7 After that he sent out a raven, and it continued flying outdoors, going and returning, until the waters dried off the earth.
(Genesis 9:12-16) . . .And God added: “This is the sign of the covenant that I am giving between me and YOU and every living soul that is with YOU, for the generations to time indefinite. 13 My rainbow I do give in the cloud, and it must serve as a sign of the covenant between me and the earth. 14 And it shall occur that when I bring a cloud over the earth, then the rainbow will certainly appear in the cloud. 15 And I shall certainly remember my covenant which is between me and YOU and every living soul among all flesh; and no more will the waters become a deluge to bring all flesh to ruin. 16 And the rainbow must occur in the cloud, and I shall certainly see it to remember the covenant to time indefinite between God and every living soul among all flesh that is upon the earth.”
The Insight Book fails to address the issue directly:
Volume 2 p. 730 RainbowThe Bible does not describe the degree of clarity of the atmosphere just prior to the Flood. But apparently atmospheric conditions were such that, until a change came about when "the floodgates of the heavens were opened" (Ge 7:11), no others before Noah and his family had seen a rainbow. Even today, atmospheric conditions affect whether a rainbow can be seen or not.