photo #8581036

Altocumulus stratiformis undulatus spotted over Mt. Batur, a volcano on the island of Bali, Indonesia by Steven Grueber (Cloud Appreciation Society Member 41,808). Cloudlets of Altocumulus line up into ridges like this when there is wind shear. This is when the wind speeds or directions above and below the cloud differ markedly. This is the sky’s equivalent of the ridges of sand beneath your feet as you walk along the water’s edge of a beach.