Moonbow at Upper Yosemite Fall.

A moonbow (also known as a lunar rainbow) is a rainbow produced by light reflected off the surface of the moon rather than from direct sunlight. Many photographers ascend on Yosemite between April - July during a full moon to capture a moonbow either at the Upper Yosemite Fall, or at the Lower Yosemite Fall, Several factors are required to capture a Moonbow.
1. Bright Moonlight (nearly-full moon)
2. Moon risen above the south rim of the valley (so moonlight can strike Upper Yosemite Fall)
3. Sufficient mist and spray during snow melt runoff;
4. Clear skies.
5 Dark skies (Sun more than 9 degrees below the horizon)
6. Geometry (the angle between the "anti-lunar direction" [ observer's shadow cast by the moonlight] and the direction toward the base of the Upper Yosemite Fall must be near the "rainbow angle" of 42 degrees)
This image was made on June 14, 2011 at 10:47 pm
© Copyright Jerry Gilligan 2011 All Rights Reserved.

Moonbow at Upper Yosemite FallsLunar RainbowYosemiteNational Parksnow runoffMoonbowUpperFall