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Jeju draws NASA’s eye with unusual cloud formation

Published: 26 Feb. 2026, 17:03 Updated: 26 Feb. 2026, 18:08

A von Karman vortex street over Jeju Island, released by the National Aeronautics and Space Administration (NASA) on Feb. 24. [NASA]

A distinctive cloud pattern that looked like braided twists stretching across the sky near Jeju Island was captured by a National Aeronautics and Space Administration (NASA) satellite, NASA said Tuesday as it released images of the area.

The image, taken last Thursday by the Moderate Resolution Imaging Spectroradiometer aboard NASA’s Terra satellite, shows clouds forming a staggered line of alternating swirls as winds flowed past the volcanic island. The seas nearby also appeared turbulent, with discolored water visible off the Chinese coast.

NASA attributed the cloud formation to a von Kármán vortex street, a phenomenon that can occur when wind passes a stationary obstacle such as an island or mountain.

“If winds are too weak, clouds simply flow smoothly past,” NASA said. “If winds are too strong, vortices cannot maintain their shape.” The agency pointed out winds during the winter season were aligned in just the right way to produce the spiraling pattern in Jeju’s wake.

NASA also highlighted Jeju’s unique topography, noting that Korea’s highest point is not in the Taebaek Mountains along the east coast but at Hallasan, the volcanic peak rising from Jeju Island to about 1,950 meters above sea level.

Korea’s Cheollian-2A weather satellite also observed a von Kármán vortex street over Jeju’s skies on the morning of Feb. 12, according to the Korea Meteorological Administration (KMA). The KMA announced the phenomenon typically requires atmospheric instability that can produce cumulus clouds, steady winds with a consistent direction and terrain that rises above the cloud layer.

The NASA images also showed a long band of muddy water extending into the Yellow Sea from the coast of China’s Jiangsu province. Sediment-laden water is present in shallow coastal areas year-round, but broad sediment plumes are commonly seen in winter and may be tied to seasonal shifts in currents and vertical mixing in the water column, according to NASA.

Jeju has also been dealing with large inflows of Asian wireweed, Sargassum horneri, believed to be drifting in from waters off southern China. The seaweed typically washes ashore between March and June, but this year it began arriving as early as January, leading the provincial government to launch its response earlier than usual.

This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
BY CHON KWON-PIL [[email protected]]