Winds sculpt the landscape of the Saharan coastline of West Africa. Here, the Atlantic Ocean meets arid land, and northerly winds push the sand in streaks parallel to the coast.
This image, released today (June 30) by NASA's Earth Observatory, was taken from the International Space Station on May 20. The astronaut's-eye-view reveals puffy clouds off the coast and ripplelike internal waves headed toward the shore. Internal waves are waves that occur almost entirely below the ocean's surface. Warm, less-salty water moves through colder, saltier water; these masses of water can be hundreds of feet tall. Some are more than 550 feet (170 meters) in height, according to researchers from MIT who are studying the phenomenon.
On the surface, internal waves often leave a footprint only a few inches tall, but sunglint, or sunlight reflecting off the surface, highlights these waves in photographs from space, according to NASA's Earth Observatory.
Other desert features stand out in this image. Silvery splotches reveal salt flats called sabkhas. Sand streaks parallel to the coast are caused by winds blowing from north to south, scouring the desert as they travel. Right off the coast, waves erode the sandy shore, staining the near-shore water aqua.
As alien as this desert world may seem, the mark of human hands is visible in this photograph. On the left of the image, a light line running from the inland to the coast is a phosphate transport corridor. Roads, railways and conveyer belts move phosphate along this corridor, for use in making phosphorus, a major ingredient in fertilizers. Phosphorus is also used to make steel and to make compounds used in the manufacture of flame retardants, plastics and pesticides.
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