Kelvin-Helmholtz Clouds and Iridescence

January 17, 2005

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Provided and copyright by: Cathy Schultz
Summary authors & editors: Cathy Schultz

This small section of Kelvin-Helmholtz clouds caught my eye while driving along the New York Interstate (outside of Syracuse) near noon on November 26, 2004. By the time I managed to get to the side of the road and pull out my camera they were begining to break up. If you look closely, some iridescence can be detected along the right side of the photo.

Kelvin-Helmholtz clouds are also referred to as shear-gravity waves. They tend to develop between two layers of air, having different densities, traveling at different speeds. For example, if a warm layer exists over a layer of colder (denser) air, and if the wind shear across the two layers is sufficiently strong, eddies can form along their boundary. This results in the wavy appearance of the clouds. Unlike other Kelvin-Helmholtz structures I've seen, these appeared to be three dimensional rather than a single row of "surf waves."

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