Probably long before there was any human being to see it. It is a natural phenomenon of light and atmospheric moisture. ---- The Genesis account tells us the precise year, month, and day when the deluge began, when and where the ark came to rest and when the earth dried off. two genealogical accounts in the bible testify that noah was a real person. Ezra and Luke were careful researchers. References to noah or the flood were made by many different religions and their written logs. i would like more scientific information on how rainbows are seen because before this event there was never a rainbow. this is intensily important as it will inable us to know what the earth was like 1000 years bc. ---- The Bible is not an appropriate source for scientific information. But if you are looking at the biblical account of the rainbow shown to Noah, note that it simply says that God sets a [rain]bow in the sky and not that it is the first one ever. The conditions that cause rainbows are possible whenever there is moisture in the air.