Yosemite Moonbows: A View Of Rainbows At Night

Ever see a rainbow at night? Moonbows (aka lunar rainbows) are a rare and mesmerizing phenomenon caused by light from a full moon shining on rain or the spray of a large waterfall. This first-of-its-kind video captures the famous moonbows of Yosemite National Park in a way that has never been seen before – by filming at real-time speed!

Until recently, the only way to film by moonlight was to use timelapse to gain more light through longer exposures. While timelapse is a useful filming technique, the fast motion doesn’t illustrate the immense scale of Yosemite’s waterfalls. I wanted to capture a true-to-life moonbow experience using a cinematic 24 frames-per-second frame rate. To meet this goal, I started experimenting with a new camera, fast lenses, and advanced noise-reduction software during the 2016 moonbow season. Every April, May, and June since then I would collect more footage and refine my low-light shooting skills while enjoying the incredible beauty of Yosemite in spring. In all, the footage in this video was filmed during 11 separate visits to Yosemite.

Filming at 24 frames-per-second allowed me to capture brief details that would easily be missed by timelapse. The shooting star (see if you can spot it!) was my favorite fleeting moment. I also enjoyed being able to film the fine textures of the falling water, the hypnotic ebb and flow of the wind-borne mist, and the excited reactions from people enjoying Yosemite at night. Filming at normal speed also accommodated live audio recording of Yosemite’s nocturnal soundscape.

In addition to the technical challenges of filming moonbows, I also needed to know when and where to see them. As with rainbows, moonbows require a precise alignment of the light source (the full moon, in this case), an area of rain or mist in the air, and the person observing. Using 3D-modeling software, I developed a method to visualize when moonbows could be seen for a given location. These calculations have helped me discover new compositions for photographing this striking phenomenon, and in 2018 I created the website YosemiteMoonbow.com so that I could share this information with others who want to see the moonbow from popular vantage points in the park.

Moonbows are just as common in nature as rainbows, but they often go unnoticed because human vision isn’t as sensitive to color in low light.  When you first arrive at the base of the falls, you might see the bow as a gray arc in the mist, but as your eyes get acclimated to the dark, the moonbow will grow more vivid, especially when wind intensifies the spray. Compared to humans, cameras are much better at perceiving color in the dark, easily revealing the hidden beauty of moonlit nights.

Capturing the Yosemite moonbow with video hasn’t been easy.  These dark scenes are a stretch for even the best low-light cameras, to say nothing of the challenges of trying to do quality photography while being sprayed with water in the cold dark of night.  But that’s all part of the moonbow experience.  There’s something a little wild about heading out into the forest at night to stand in the spray of a raging waterfall, but it’s always a good time!

Learn more about moonbows in Yosemite by visiting yosemitemoonbow.com

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