March 4, 2011 - Cloud vortices off Cheju Do, South Korea

Cloud vortices off Cheju Do, South Korea

On a wintery day in early March, 2011, cold north to northwesterly winds prevailed across the Korea Strait. As persistent winds blew across the island province of Cheju Do, South Korea, the tallest mountain on the island, Mt. Halla (6,400 feet) blocked air flow, causing turbulence on the lee side of the island.

When air flows around an object with a broad face, such as a mountain, a sinuous turbulence results. Immediately behind the object, the air waves rhythmically back and forth (think of a flag waving on a flagpole), then creates rolling vortices which rotate in opposite directions, one clockwise and the next counterclockwise. The sinuous pattern created as air flow is disturbed by an object standing in the way is called a von Karman vortex street and, when the turbulence flows through clouds, the resulting pattern can be spectacular.

In this image, captured at 3:25 UTC on March 2, 2011, by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite, the oval form of Mt. Halla can be seen presenting its broadest face perpendicular to the prevailing wind. A single s-shaped cloud formation trails delicately off the leeward side of the mountain, and a von Karman vortex street decorates the clouds in a typical, paisley-like, pattern.

Image Facts
Satellite: Terra
Date Acquired: 3/2/2011
Resolutions: 1km ( B), 500m ( B), 250m ( B)
Bands Used: 1,4,3
Image Credit: Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC