During the spring months in Yosemite, you can see a Yosemite falls produce a moonbow during full moons. Not easy to view with the naked eye, a camera with a polarizing filter has no problem capturing the magical event. Yosmemite is great park to visit during any season, but spring time is the best season for viewing Yosemite falls as it roars to life during the spring snow from snow melt.

From the UNESCO website:

Yosemite National Park vividly illustrates the effects of glacial erosion of granitic bedrock, creating geologic features that are unique in the world. Repeated glaciations over millions of years have resulted in a concentration of distinctive landscape features, including soaring cliffs, domes, and free-falling waterfalls. There is exceptional glaciated topography, including the spectacular Yosemite Valley, a 914-meter (1/2 mile) deep, glacier-carved cleft with massive sheer granite walls. These geologic features provide a scenic backdrop for mountain meadows and giant sequoia groves, resulting in a diverse landscape of exceptional natural and scenic beauty.