Science is Fun Fridays!
You may have seen some images or video of this last week, rare supercilium clouds in Santa Cruz. "Supercilium" means eyebrow in Latin, identifying the arc shapes. They develop in turbulent mountain air rushing downwind. But it's an unofficial classification, not formally listed in the International Cloud Atlas. It is a more recent proposed supplementary feature of already established altocumulus, stratrocumulus, or cirrocumulus clouds.