Cirrocumulus clouds form at high altitude. They are primarily composed of ice crystals but also contain supercooled water droplets.
The photograph of cirrocumulus clouds was taken in Las Virgenes Canyon on a trail run from the Victory Trailhead of Upper Las Virgenes Canyon Open Space Preserve, also known as Ahmanson Ranch.
Some related posts: Pattern Change Ahead, Fallstreak Hole, Rainbow Colors in Cirrus Clouds Over Los Angeles