Genesis 9:12-16 (12) And God said, "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: (13) I have set my rainbow in the clouds, and it will be the sign of the covenant between me and the earth. (14) Whenever I bring clouds over the earth and the rainbow appears in the clouds, (15) 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. (16) 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."
when ever there is clouds over the earth and the rainbow appears in the clouds (which is in rain) thats what i meant
u know that the rain in the sky acts as a prism to scatter all the visible light into separate sections (rainbow)
before the flood it was believed there was no rain and that water came from the ground to give water to plants and man