On January 18, 2013 the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite passed over the island province of Cheju Do, South Korea and captured a delicate paisley-like pattern in the clouds to south of the island. The swirls are known as von Karman vortex streets, and are created by the turbulent flow on wind.
When flowing air smacks into a broad, immobile object, such as a mountain, the turbulence created as the disrupted air pushes around the object forms a mathematically predictable pattern on the lee side of the object. In this case, a strong northerly stream of air has been disrupted by the mountains on the island, particularly Mt. Halla, which rises to 6,400 feet.
At high resolution, Mt. Halla can be seen presenting its broad face to the wind. A small, round bank of clouds forms over the peak of the mountain, while on the northerly side clouds appear to pile up as the airflow stops. On the south side of the mountain, the disrupted air flow leaves a cloudless semi-circle as the von Karman vortex street begins to form.