Share

What's Making these Clouds Swirl?

Chris Dolce | TWC
Published: February 4, 2013

von Karman Vortices

von Karman Vortices

NASA

Near Guadalupe Island off the coast of Baja California on June 21, 2012.

  • von Karman Vortices
  • von Karman Vortices
  • von Karman Vortices
  • von Karman Vortices
  • von Karman Vortices
  • von Karman Vortices
  • von Karman Vortices
  • von Karman Vortices
  • von Karman Vortices
  • von Karman Vortices
  • von Karman Vortices
  • von Karman Vortices
  • von Karman Vortices

The swirling cloud features you see adjacent to several island locations around the world are known as von Karman vortices. They are named for Theodore von Karman, who is the first to describe them.

Animation from NASA.gov showing the formation of von Karman vortices. The white cylinder on the far left is the disturbance, which in the case of the images above would be the islands. Credit: Cesareo de la Rosa Siqueira at the University of Sao Paulo, Brazil

In each of the cases shown above, islands with significant elevation rises are the disturbance that triggers the formation of the vortices.

Simply put, clouds are forced to go around the islands by the prevailing winds. The air in the lower atmosphere diverges as it goes around the island and then converges on the opposite side, forming the spinning vortices downwind of the islands. The vortices alternate their direction of rotation.

This phenomenon is not just related to clouds; it can happen anywhere that fluid flow is disturbed by an object, according to NASA's website on von Karman vortices.

Featured Blogs

Heavy Rainfall Trends

By Christopher C. Burt
August 22, 2014

Yet another phenomenally intense rainfall event has occurred in the U.S. this morning (August 22nd) when 3.95” of rain in one hour was measured by a COOP observer at a site 3 miles southwest of Chicago’s Midway Airport. The return period for such at Midway Airport (according to NOAA’s ‘Precipitation Frequency Data Server’) is once in 500 years. This is similar to the Baltimore, Detroit, and Islip, New York events last week (although the Islip event was probably more in the range of once in a 1000 years). Brian Brettschneider of Borealis Scientific LLC has kindly offered this guest blog today featuring research he has done on heavy rainfall trends for 207 sites across the U.S. for a homogenous POR of 1949-2013.

Atlantic Disturbance 96L (Interim Update)

By Dr. Jeff Masters
August 22, 2014

Live Blog: Tracking Hurricane Arthur as it Approaches North Carolina Coast

By Shaun Tanner
July 3, 2014

This is a live blog set up to provide the latest coverage on Hurricane Arthur as it threatens the North Carolina Coast. Check back often to see what the latest is with Arthur. The most recent updates are at the top.

Tropical Terminology

By Stu Ostro
June 30, 2014

Here is some basic, fundamental terminology related to tropical cyclones. Rather than a comprehensive and/or technical glossary, this represents the essence of the meaning & importance of some key, frequently used terms.

2013-14 - An Interesting Winter From A to Z

By Tom Niziol
May 15, 2014

It was a very interesting winter across a good part of the nation from the Rockies through the Plains to the Northeast. Let's break down the most significant winter storms on a month by month basis.

What the 5th IPCC Assessment Doesn't Include

By Angela Fritz
September 27, 2013

Melting permafrost has the potential to release an additional 1.5 trillion tons of carbon into the atmosphere, and could increase our global average temperature by 1.5°F in addition to our day-to-day human emissions. However, this effect is not included in the IPCC report issued Friday morning, which means the estimates of how Earth's climate will change are likely on the conservative side.