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tlr online
29-04-04, 08:11
The Cape Verde Islands, off of North Africa's western coast in the Atlantic Ocean, cause cloud vortex streets to form in their wake, as is shown here in this true-color image. Wind moving across the scene gets disturbed by passing over and around the islands, which cause eddies to form. These eddies take the shape of vortices, and because the wind is all moving in the same general direction, the vortices line up into "streets." These vortex streets are visible because of the clouds riding the winds.

Not only are the clouds forming interesting patterns, but the clouds themselves have varied textures. Along the right side of the image, the moist air allows a thick, fairly uniform layer of clouds to form. But toward the center of the image, the cloud pattern changes into "open-celled" clouds. This type of cloud forms when hot air rises at the edge of the cell, causing clouds to forum, while colder air sinks in the center, causing moisture to evaporate. And at the left side of the image, "closed-celled" clouds form: warm air rises in the center and sinks around the edges, so clouds appear in cell centers, but evaporate around cell edges.

This is an Aqua MODIS image from April 26, 2004.

http://modis.gsfc.nasa.gov/gallery/images/image04292004_md.jpg

Copyright 2004 NASA