Double rainbows occur when sunlight is reflected twice inside raindrops, creating a secondary rainbow that appears outside the primary one.

Third and fourth strands of the rainbow are visible - the first two are behind the photographer Only five triple rainbows had been spotted in the last 250 years ...

Light refracting and reflecting through a water-filled round-bottom flask makes a rainbow, as light through a raindrop does. A faint secondary rainbow may be visible. The flask has a reflective ...