|NASA Photo ID||ISS011-E-9756|
|Time taken||07:42:24 GMT|
1000 x 688 pixels 540 x 372 pixels 540 x 405 pixels 3032 x 2008 pixels 639 x 435 pixels
|Kodak DCS760c Electronic Still Camera|
|3060E: 3060 x 2036 pixel CCD, RGBG array|
|1000 pixels||688 pixels||No||Yes||Earth From Space collection||Download Image|
|540 pixels||372 pixels||Yes||Yes||Earth From Space collection||Download Image|
|540 pixels||405 pixels||Yes||Yes||NASA's Earth Observatory web site||Download Image|
|3032 pixels||2008 pixels||No||No||Not enhanced||Download Image|
|639 pixels||435 pixels||No||No||Download Image|
This detailed view of the remote Conception Bay sector of the Namibian coastline shows breakers and a strand plain on the left and complex dunes of the Namib dune sea on the right. A strand plain is a series of dunes, usually associated with and parallel to a beach, sometimes containing small creeks or lakes. The complexity and regularity of dune patterns in the dune sea of the Namib Desert have attracted the attention of geologists for decades; however, they remain poorly understood. The flat strand plain (~4 kilometers shown here) shows a series of wet zones that appear black where seawater seeps inland and evaporates. These patches are aligned with the persistent southerly winds, some of the strongest of any coastal desert.
The southerlies blow sand from the beaches--where it is constantly mobilized by wave action--and pile it up as dunes many tens of feet high. Note how the crests of the dunes, catching the morning light in this view, are aligned in a marked northwest-southeast orientation. These crests form transverse to the formative wind (i.e. crosswise), revealing an interesting feedback with the wind. The dunes act as obstacles, and obstacles cause winds to be deflected significantly to the right, in the southern hemisphere--in effect reorienting the southerly wind as a southwesterly wind. The higher the sand dunes grow, the more this effect comes into play.