 A peculiar turbulent cloud pattern, named von Kármán vortices, is sometimes observed over the Sea of Japan.It requires a stable field of low clouds driven by the wind over a small (isolated) and tall obstacle, and usually forms over small mountainous islands.The Sea of Japan meets these conditions as it has frequent winds and cloudy skies, as well as compact, tall islands such as Rishiri (), Ulleungdo () and Ōshima ().