Barchan dunes in Tenere Desert (Sahara),Niger. The major requirement for dune-building is a sand supply; in deserts this is transported by wind from areas of erosion. Barchan (crescent-shaped) dunes are formed in desert areas where the pre- vailing wind blows from one direction. In this photograph it would be blowing from left to right. An oval shape forms upwind and behind it a slip face as sand blows over the summit of the dune,and two wings spread out downwind. Such dunes grow at the rate of wind deposition and advance forward at a speed subject to the wind. Barchans typically occur in belts up to 300km long and over 12km wide. Note also the wind ripple effect | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Buxton, Tony |
Bildgröße: | 4150 px × 3226 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |