sunbow

/ˈsʌnˌboʊ/
noun
  1. A rainbow-like arc of colors seen in mist or spray illuminated by sunlight, similar to a rainbow but formed by sunlight rather than rain.
    • We saw a beautiful sunbow in the spray of the waterfall.
    • The morning mist created a faint sunbow over the lake.
    • Photographers often try to capture a sunbow in the ocean surf.