Supernumerary bow

(Section 3.2.3.5.3)

These are rainbows bordered by narrow coloured bows (green, violet or orange) due to interference of light waves. They occur inside the primary rainbow or on rare occasions outside the secondary rainbow. When raindrops are large (greater than 1 mm in diameter), the diffraction pattern may have up to five supernumerary bows, the first merged with the primary bow, and all repeating the vivid colour pattern. With smaller drops, fewer supernumerary bows form.