Biblically speaking, the rainbow is
the sign of a covenant
that God made with the whole earth: He will never destroy the earth again with a flood. The rainbow is literally correlated to
rainfall. God made this covenant,
with the rainbow as the token,
after the waters of the flood receded and
Noah and his family exited the ark.
God Said,
"I establish my covenant with you:
Never again will all life be destroyed
by the waters of a flood;
never again will there be a flood to destroy the earth. . . .
This is the sign of the covenant
I am making between me and you
and every living creature with you, a covenant for all generations to come: I have set my rainbow in the clouds, and it will be the sign of
the covenant between me and the earth.
Whenever
I bring clouds over the earth and
the rainbow appears in the clouds,
I will remember
my covenant between me and you
and all living creatures of every kind. Never again will the
waters become a flood to destroy all life.
Whenever the rainbow appears in the clouds,
I will see it and remember the everlasting covenant
between God and all living creatures of every kind on the earth”
(Genesis 9:11–15).
God made this promise, signified by the rainbow,
not only to mankind
but to “every living creature . . . the birds, the livestock and all the wild animals,
all those that came out of the ark . .
every living creature on earth”
(Genesis 9:9–10).
The covenant is perpetual, enduring
to all generations.