Today's image, captured by the MODIS on the Aqua satellite on February 6, 2008 shows the Labrador Sea, and the unusual cloud formations over it. The Labrador Sea is an arm of the North Atlantic Ocean that lies between Labrador and Greenland.
The lines of clouds are called "cloud streets." These are caused when low-level winds moving between and over obstacles cause the clouds to line up into rows (much like streets) that match the direction of the winds. At the point where the clouds first form streets, they're very narrow and well-defined. But as they age, they lose their definition, and begin to spread out and rejoin each other into a larger cloud mass.