The interplay of wind and landmass near Jeju Island, South Korea, has created a stunning visual phenomenon: swirling cloud patterns and turbulent waters captured in a recent satellite image. NASA’s Terra satellite, using the Moderate Resolution Imaging Spectroradiometer (MODIS), documented these “showy swirls” on February 19, 2026, revealing the complex atmospheric and oceanic processes at play in the region. This striking imagery highlights the dynamic relationship between the island’s unique geography and the surrounding environment.
Jeju Island, rising approximately 1,950 meters (6,400 feet) above sea level, isn’t just South Korea’s highest point; it’s a volcanic landmass that significantly influences regional weather patterns. The island’s peak, Hallasan, a shield volcano that last erupted in the 11th century, is responsible for the formation of what are known as von Kármán vortex streets – the swirling patterns visible in the NASA imagery. These vortex streets are a fascinating example of fluid dynamics in action, demonstrating how air flows around obstacles.
The formation of these vortex streets requires specific conditions. According to the Weather Underground, winds require to be within a “sweet spot” – between 18 and 54 kilometers (11 and 34 miles) per hour – to create the counterrotating vortices that trace the airflow. Too little wind and the clouds flow smoothly; too much, and the vortices dissipate. The February 19th conditions were ideal, resulting in the wispy, yet defined, swirls observed by MODIS. Similar patterns were observed the previous day, though with slightly different characteristics.
NASA Earth Observatory image by Michala Garrison, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview.
Von Kármán Vortex Streets: A Fluid Dynamics Phenomenon
Von Kármán vortex streets aren’t limited to cloud formations; they occur whenever a fluid – whether air or water – flows past a stationary object. The trailing, staggered spirals are a direct result of the object disrupting the fluid flow. The phenomenon has been observed in various settings, from water flowing around rocks to air moving past buildings. The appearance of these vortices can vary, sometimes appearing wispy and other times forming sharply defined rows, as seen near Jeju Island.
Turbulence Below the Surface
The turbulence wasn’t limited to the atmosphere. The MODIS image also revealed colorful, turbulent water surrounding Jeju Island. To the west, a large plume of sediment originating from the coast of China’s Jiangsu province turned the waters murky. Whereas sediment plumes are common in this area, particularly during the winter months, the extent of this plume was notable. Research from the NASA Earth Observatory suggests that seasonal changes in currents and vertical mixing of the water column contribute to these large winter plumes.
Jeju Island: A Unique Volcanic Landscape
Jeju Island’s geological significance extends beyond its height. Designated a UNESCO World Heritage site in 2018, the island boasts a unique volcanic landscape, including Hallasan and a network of lava tubes. The UNESCO designation recognizes the island’s exceptional geological value and its importance as a natural laboratory for studying volcanic processes. The Global Volcanism Program also provides detailed information on Halla, the volcano at the island’s center.
The recent NASA imagery provides a captivating glimpse into the complex interplay of atmospheric and oceanic forces shaping the environment around Jeju Island. Continued monitoring of these phenomena will be crucial for understanding regional climate patterns and the impact of geological features on weather systems. As satellite technology advances, we can expect even more detailed observations of these dynamic processes, offering valuable insights into our planet’s intricate systems.
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