Prevailing winds in this part of the Sahara Desert blow from the northeast. (Note that north is to the right.) The wavy dunes are aligned transverse (roughly right angles) to these winds. The sand that makes the dunes is blown in from a zone immediately upwind (just out of the bottom of the image), where dry river beds and dry lakes provide large quantities of mobile sand. This pattern is typical in the western Sahara Desert, where plateau surfaces are mostly dune free and dune fields are located in the surrounding lowlands. Larger rivers deposit sandy sediment on the few occasions when they flow, sometimes only once in decades.
Astronaut photograph ISS038-E-26862
was acquired on January 8, 2014, with a Nikon D3S digital camera using a
180 millimeter lens, and is provided by the ISS Crew Earth Observations
experiment and Image Science & Analysis Laboratory, Johnson Space
Center. The image was taken by the Expedition 38 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed.
The International Space Station Program supports the laboratory as part of the ISS National Lab
to help astronauts take pictures of Earth that will be of the greatest
value to scientists and the public, and to make those images freely
available on the Internet. Additional images taken by astronauts and
cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by M. Justin Wilkinson, Jacobs at NASA-JSC.
- Instrument:
- ISS - Digital Camera - NASA
