Kelvin-Helmholtz Clouds & Rays

Regular Kelvin-Helmholtz instability wave clouds cast their shadows across the sky in Arizona. Pictures by Alan Clark.

Images ©Alan Clark, shown with permission
Changes in the waves over several minutes recorded by Alan Clark.

K-H wave development

About - Submit Optics Picture of the Day Galleries Previous Next Today Subscribe to Features on RSS Feed
Kelvin-Helmholtz instability waves arise when two fluids are travelling at different speeds producing shear at their interface. Small disturbances become magnified into regularly spaced rotating structures.

In this case the layers are of air at different temperature and density.  Presence of atmospheric K-H waves indicates significant air turbulence.

Earth sized waves - Jupiter's red spot, 2-3 Earth diameters across, results from Kelvin-Helmholtz instability. This image by Voyager 2 shows several atmospheric streams at different velocities with K-H waves at their boundaries. The red spot rolls between two particularly strong jet streams.

Image courtesy NASA