primary rainbow

A primary rainbow is an atmospheric phenomenon that appears as a series of concentric colored arcs. It is formed when sunlight enters raindrops, causing refraction and dispersion of light into its component colors. This is similar to how a prism separates light. The light then undergoes one internal reflection within the raindrop before exiting and being refracted again, further separating the colors. The most brilliant rainbow, the primary bow, results from this single internal reflection. The colors are arranged with red on the outside edge of the bow, and the observer sees it in the direction opposite the Sun.123