It is a beautiful and colorful aspect of G‑d’s world, but it’s also a reminder of tragedy. We are taught not to stare at it, but we do make a special blessing when it appears in the sky.

Let’s see what the Torah has to say about the rainbow.

The Covenant

As a result of the moral decay of the generation, 1,656 years after the world was created, G‑d flooded the world and destroyed it. The only survivors of the Flood were Noah, his family and the animals that were on the ark with them.

After a year, when they were finally able to leave the ark. Noah built an altar and brought sacrifices to G‑d. What happened next is recounted in the Torah portion of Noah:1

G‑d smelled the good smell [of Noah’s sacrifices] and He said to Himself: I will no longer curse the land because of man, since man’s inclination is evil from the time of his youth. I will never again destroy all living things, as I’ve just done…

And G‑d said to Noah and his sons: I will keep my covenant with you and your descendants…and never again will a flood destroy all life, and there will not be another flood destroying the earth….This is the sign I am making, testifying to the covenant between Me and you and all living souls, forever:

I have put my rainbow in the clouds, and it will be the sign of the covenant between Myself and the world. When I send clouds over the earth, the rainbow will be seen in the clouds, and I will remember the covenant between Myself and yourselves and all living souls, and there will never again be a flood to destroy all life. The rainbow will be in the clouds and I will see it and remember the eternal covenant between G‑d and all the living souls on earth.

After the Flood, the Creator promised that—in spite of how man might sin—He would never again make a flood that would destroy the world. He created the rainbow as a sign, a reminder of this covenant He made with the world.

What Blessing Do We Say When Seeing a Rainbow?

When a rainbow appears in the sky, it is considered a sign that we have sinned, but G‑d has remembered His covenant. Therefore, when seeing a rainbow, it is appropriate to thank G‑d for not making another flood. We thank G‑d by making a special blessing.

The sages of the Talmud disagree about the blessing that should be said.2 One opinion is that we should say, “Blessed are You…who remembers the covenant,” while another opinion prefers, “Blessed are You…Who is faithful to His covenant and stands by His word.”

The final decision melds the two opinions into the following blessing:

“Blessed are You, G‑d, Ruler of the world, who remembers the covenant, who is faithful to His covenant, and who stands by His word.”

A Generation Without a Rainbow

Since the rainbow is a sign that mankind is sinning, a generation that never sees a rainbow is on an especially high level of spirituality and righteous conduct.3

The Midrash4 tells of several generations in which there were such righteous people that no rainbow was seen in their lifetimes: the generation of King Chizkiyahu, the era of the Men of the Great Assembly, the generation of Rabbi Shimon bar Yochai5 and the generation of Rabbi Yehoshua ben Levi.6

When no rainbow appeared in the heavens, it was the ultimate sign that there lived a person so righteous that he was a foundation-stone of the world. The Talmud7 tells about a meeting between Rabbi Yehoshua ben Levi and Rabbi Shimon bar Yochai in Gan Eden (Heaven). Rabbi Shimon asked Rabbi Yehoshua if the rainbow had been seen in his lifetime. When Rabbi Yehoshua modestly hid his greatness by saying that it had, Rabbi Shimon said, “Then you’re not ben Levi!”

Natural Phenomenon or New Creation?

A rainbow is a natural phenomenon with a simple scientific explanation. Since one can assume that the mechanics for rainbows came into being during the six days of creation,8 the question arises: what exactly happened after the Flood, when the Creator announced that the rainbow would be a sign of the covenant that He’d established with Noah and his sons?

Several explanations have been given.

Nachmanides posits that the rainbow existed long before the Flood, but after the Flood, the Creator decided to make it a sign that mankind was sinning.

Rabbi Avraham ibn Ezra and Abarbanel say that, with the Flood, there were physical changes in the world that allowed the rainbow to become visible. According to Ibn Ezra, sunlight became stronger. According to Abarbanel, the atmosphere became thinner.

The Lubavitcher Rebbe explains in the light of Chassidic teachings: Even though the Flood brought destruction to the world, there was also an aspect of it that was a blessing. The Flood purified the world in the sense that it gave man the ability to refine the material. The clouds, which are formed from the mist that rises from the ground, represent this transformation of the material into something ethereal. After the Flood, the clouds were thinner (allowing rainbows to form), symbolizing the ability for human endeavor to purify the material world.

Kli Yakar has another explanation: He says that the rainbow was always visible, but in righteous generations, there was less sin, and the populace was so confident that nothing would happen to them that they didn’t bother to look at the rainbow and worry about it being a harbinger of evil.9

The Beauty of the Divine Presence

A rainbow isn’t only a sign of sinning; it can also signify divine revelation. The prophet Ezekiel10 described a vision in which he had seen the divine presence “like a rainbow in the clouds on a rainy day, with a corona around it; this was how the glory of G‑d appeared, and I saw it and fell on my face and heard a voice speaking….”

Because of this vision, there was a Talmudic sage11 who said that when a person sees a rainbow, he should bow down, prostrating himself in front of G‑d. Others, however, said it was forbidden to do so because it would look like one was worshipping the rainbow.

However, since the rainbow represents the beauty of the divine presence and the glory of the Creator, the Talmud12 teaches that it’s not proper to stare at a rainbow. However, it is permitted to look at a rainbow for the sake of making the special blessing on it.

A Sign of the Coming of the Messiah

The Zohar13 says that before the Messiah comes, an especially bright and colorful rainbow will appear.

May we merit seeing it soon, and in our lifetimes.