A vortex street often occurs when cloud formations over the ocean are disturbed by wind passing over land or another obstacle. In this true-color Moderate Resolution Imaging Spectroradiometer (MODIS) image from July 5, 2002, marine stratocumulus clouds have arranged themselves in rows, or streets, which are usually parallel to the direction of wind flow. Downwind of obstacles, in this case, the Canary Islands off the west African coast, eddies create turbulent patterns called vortex streets.