At mid- and high latitudes during the winter, clouds often form neat, parallel rows. Called cloud streets, these formations can persist for hundreds of kilometers if the land or water surface underneath is uniform. Persistent winds moving cold air over the ocean, combined with air moving up from the water’s relatively warmer surface produce these characteristic formations. Antartica is the coldest, windiest, and (on average) highest continent on Earth. Dry, frigid, katabatic (down-slope) winds can blow fiercely from land toward the water for days on end, setting up ideal conditions for cloud streets.
The Moderate Resolution Imaging Spectroradiometer (MODIS) flying onboard NASA’s Aqua satellite took this picture on August 14, 2006. The image shows cloud streets rolling off the Amery Ice Shelf on the east coast of Antarctica. The ice appears as opaque white with the slightly blue tint. Immediately east of the ice shelf’s edge is an area of relatively cloud-free air, where the dark ocean surface shows through. East of this area, strong cloud streets form and streak over the ocean surface.
An ice shelf is a thick slab of ice attached to a coastline. The ice shelf is fed by a glacier, and the ice slab floats over the ocean surface. Covering approximately 62,620 square kilometers, the Amery Ice Shelf is one of Antarctica’s larger ice shelves. It is fed by the Lambert Glacier.
NASA image created by Jesse Allen, Earth Observatory, using data provided courtesy of the MODIS Rapid Response team.