Careful calculation, timing and camera location are needed for the required combination of dark sky and a bright moon in just the right position to create a rainbow in the spray from the falls.

Plus, plenty of spray. "2006 brought an unusual amount of snowfall to the Sierra Nevada mountains - about twice the average. The spring runoff was very high, causing both the thick mist critical to creating the bow and the flooded meadow necessary for the reflection."

The reflection is a 'reflected bow' produced by moonlight first refracted and reflected through spray droplets before being reflected again by the flooded meadow.

Size restrictions of a web page do not allow full justice tot his vertical panorama of three 30s exposures and a 63s exposure for the lowermost frame all within a 5 minute period.