Vortex Street and Glory
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Vortex Street and Glory

June 9, 2006

The MODIS on the Aqua satellite acquired this interesting image on May 31, 2006, showing Guadalupe Island, which is off the coast of Mexico's Baja Peninsula. Turbulence, caused by the wind passing over the island, can produce pronounced eddies that swirl the clouds into a pattern called a vortex "street". The swirls extend south from the island, which is visible through the break in the clouds.

This phenomena occurs when clouds over the ocean become aligned with the direction of a low-level wind, producing parallel rows, or streets, of clouds. When that flow is interrupted by a land mass, turbulence can create vortices that are responsible for the "eye" features, hence the name "vortex streets."

The second interesting feature of this image is the narrow, elliptical rainbow that can be seen to the left of Guadelupe Island. It is fairly faint and slightly reddish. This phenomenon is called a glory, which is often produced when light at the observer's anti-solar point falls on a cloud deck below. What is the anti-solar point? If you had been standing on the Aqua satellite as it orbited the Earth, looking down at the cloud deck below you, the sun would have been directly behind you - 180 degress from your line of sight.

Ice and water particles in the cloud bend the light and reveal all its colors, or wavelengths. Often, when a glory is seen from an airplane, viewers will see the shadow of the airplane in the center of the glory. Here is another image of a vortex street and glory over Guadalupe Island, in 2002.

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