Vortex Off California

By Tom Yulsman | June 27, 2013 12:14 pm

A vortex swirls in the cloud deck above the Pacific Ocean downwind of San Clemente Island in this image captured by NASA’s Terra satellite on June 26th. The island is at upper left. San Diego is located on the coast just at middle right.

In my last post, I used a large-scale, composite satellite image to illustrate the broiling heat wave that’s spreading out across the western United States. But I also made note of the fascinating detail I spotted in the Pacific Ocean off California and Mexico, and I asked whether you could spot a hurricane-like feature in the cloud deck.

Here it is, in close up, in the image at the top of the post. And of course it’s not a hurricane. I’m not certain, but I believe it is a Von Karman vortex. Here’s a fabulous little animation of the phenomenon:

This animation was posted originally by the Goddard Earth Sciences Data and Information Services Center, which offers an excellent detailed explanation. In short:

From the perspective of physics, both the ocean and atmosphere are actually fluids. And when the movement of a fluid is disrupted by an obstacle, the flow is disrupted downstream. In the case of the feature captured in the satellite image at the top of this post, San Clemente Island at upper right is an obstacle. And it appears to have disrupted the airflow over and around it in such a way as to produce the vortex feature in the clouds lower down in the image.

Typically, a line of such vortices forms downwind of an island obstacle. They’re called vortex streets. Here’s another explanation with a cool image from NASA’s Earth Observatory. (And an example of a different kind of disturbance that can form behind islands, from one of my previous posts: “Ocean Comet.”)

In this case, however, I see just one. I’m not exactly sure why that would be the case. I’ve sent a message to the folks at the Earth Observatory seeking some insight from them. When I hear back, I’ll post an update.

  • Don Brooks

    This has been known about for a long time. Search for “Catalina eddy.”

  • Lu Mili

    yesterday I went to the beach in Redondo Beach, and the fog was very strong, can,see much nothing, I have been living by the beach my entire life and yesterday was a weird weather. I was remember this that happen in Italy http://www.meteoweb.eu/2013/06/reportage-fotografico-le-piu-belle-immagini-delle-spettacolari-trombe-marine-di-ieri-in-istria/211852/

  • ConcernedHistorian

    This happens off of all of the Channel Islands. San Clemente has one of the biggest effects because it’s peak system is close to perpendicular to prevailing wind flow. However; I have experienced similar unpredictable wind patterns south east of Santa Cruz, when the winds are following the jet stream south down the coast. Makes the Hardway Race a real pain sometimes.



ImaGeo is a visual blog focusing on the intersection of imagery, imagination and Earth. It focuses on spectacular visuals related to the science of our planet, with an emphasis (although not an exclusive one) on the unfolding Anthropocene Epoch.

About Tom Yulsman

Tom Yulsman is Director of the Center for Environmental Journalism and a Professor of Journalism at the University of Colorado, Boulder. He also continues to work as a science and environmental journalist with more than 30 years of experience producing content for major publications. His work has appeared in the New York Times, Washington Post, Audubon, Climate Central, Columbia Journalism Review, Discover, Nieman Reports, and many other publications. He has held a variety of editorial positions over the years, including a stint as editor-in-chief of Earth magazine. Yulsman has written one book: Origins: the Quest for Our Cosmic Roots, published by the Institute of Physics in 2003.


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