A semicircular bow or arc exhibiting a spectrum of colors. There is no separate Hebrew word for rainbow, so the normal word for “bow” (with which to shoot arrows) is used in the Bible.—Gen. 9:13; Ezek. 1:28.
Complicated theories and formulas are used to explain the formation of a rainbow. Basically, it seems that as white light enters a raindrop it is refracted into different colors, the drop acting like a tiny prism. Each color strikes the inner surface of the drop and is reflected back at a different and specific angle. Thus an observer sees a bow with all seven colors of the spectrum (from the inside of the arc outward: violet, indigo, blue, green, yellow, orange and red), though these may blend so that only four or five are clear. Sometimes a larger and less distinct “secondary” bow is formed with the colors reversed. Scientists are still studying the rainbow. The book The Rainbow, from Myth to Mathematics (pp. 320, 321) by C. B. Boyer observes: “Within a raindrop the interaction of light energy with matter is so intimate that one is led directly to quantum mechanics and the theory of relativity. . . . Although much is known about the production of the rainbow, little has been learned about its perception.”
The first Biblical reference to a rainbow is in the account of the covenant God made with Noah and his offspring after the Flood survivors came out of the ark. (Gen. 9:8-17; Isa. 54:9, 10) This splendid sight of itself would have been reassuring and an indication of peace to Noah and his family.
Many opinions have been offered as to whether this was the first time humans saw a rainbow. Some commentators have held that rainbows had been seen before and that God’s ‘giving’ the rainbow at this time was really a ‘giving’ of special meaning or significance to a previously existing phenomenon. Many of those holding this view believe that the Flood was only local or did not substantially change the atmosphere.
Nevertheless, this is the first mention of a rainbow, and if a rainbow had been seen earlier, there would have been no real force in God’s making it an outstanding sign of his covenant. It would have been commonplace, and not a significant marker of a change, of something new.
The 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” (Gen. 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.
The glory, beauty and peacefulness of a rainbow that appears after a storm are drawn upon in Biblical descriptions of God and his throne. In Ezekiel’s vision of God, the prophet saw “something like the appearance of the bow that occurs in a cloud mass on the day of a pouring rain.” This emphasized “the glory of Jehovah.” (Ezek. 1:28) Similarly, John saw Jehovah’s throne of splendor and ‘round about it there was a rainbow like an emerald in appearance.’ The restful emerald-green color of the rainbow would have suggested composure and serenity to John, and appropriately so since Jehovah is the master of every situation, a glorious Ruler. (Rev. 4:3) John also saw an angel with ‘a rainbow upon his head’ (Rev. 10:1), which may suggest that he was a special representative of “the God of peace.”—Phil. 4:9.