I found this incredible photo of Bridal Veil Falls in Yosemite National Park taken by Justin Lee on my Tumblr feed (http://jonjohns65.tumblr.com/)
According to the Daily Mail Online:
The natural wonder was captured by photographer Justin Lee, who was overjoyed to find himself in exactly the right place at the right time.
He said: 'The sun has to be in position to get the rainbow, and this photo was not planned by me beforehand. I just happened to be in the right place at the right time. 'I couldn't believe how lucky I was to see such a sight, and just had to start taking pictures straight away.'
The ideal conditions for a rainbow are the combination of sunlight and water droplets. This usually comes in the form of rain, but fine spray from a waterfall is often just as effective.