NASA recently published an interesting image of a dust storm in the White Sands dune field. The image was acquired on 28 February 2012, by an astronaut aboard the International Space Station, the largest spacecraft ever flown into space. In Fig. 1, dust from the White Sands dune field, blown by southwesterly winter winds, rises hundreds of meters from the valley floor, and drifts over the snow-covered peaks of the Sacramento Mountains.
The White Sands National Monument, located in New Mexico State, USA, lies within the 50 km wide Tularosa valley, between the dark rocks and forested slopes of the Sacramento Mountains and the San Andres Mountains. The dust clouds in this astronaut photograph extend for more than 120 km. The strong winds lofted dust particles from the valley floor, to over than 1200 m above the mountains.
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n most sand storms, the color of blowing dust is a light brown or red. In Fig. 1, two different colors are visible in the dust storm: redder dust from the hillsides north of White Sands and white dust from the dune field itself.
The sand dunes of this natural monument are white since they are composed of gypsum, a relatively rare dune-forming mineral. The dunes’ brilliance, especially contrasted against the nearby dark mountain slopes, allows astronauts to identify them easily from Earth orbit.
References
NASA Earth Observatory
http://earthobservatory.nasa.gov/IOTD/view.php?id=77775