Recent strange weather conditions have led to a number of extraordinarily bright local rainbows. They contain extra colours inside the usual violet. There are as many as three additional bands: a narrow one of orange-yellow, a wider one the vivid green of nocellara olives and a narrow one of purple. These extra bands occupy about a third of the width of the rainbow itself. What am I seeing?
• It sounds as if your questioner is seeing a supernumerary rainbow. This occurs when raindrops are relatively small and evenly sized. Light reflected inside the droplet can interfere with that reflecting…
