barchan

American  

[bahr-kahn] / bɑrˈkɑn /

noun

1. a crescent-shaped sand dune with the convex side in the direction of the wind.

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barchan British  

/ bɑːˈkɑːn /

noun

1. a crescent-shaped shifting sand dune, convex on the windward side and steeper and concave on the leeward

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Etymology

Origin of barchan

1885–90; < Russian barkhán, said to be < Turkic

Explanation

A barchan is a crescent-shaped sand dune with "horns" that point in the direction the wind is blowing. Over time, barchans migrate across sandy desert surfaces. The word barchan comes from the Kazakh language of Central Asia, a region with large areas of desert containing many barchans. A barchan forms in areas with a steady wind and limited sand. The wind pushes the sand up a gentle windward slope and over the crest, where it avalanches down the dune's steep slip, or leeward, face. The wind moves faster around the dune's edges, creating the crescent shape. Barchans are not stationary; they move, either alone or in long "trains," up to 100 feet per year.

Example Sentences

Parabolic dune shape is similar to barchan dunes but usually reversed, and it is determined more by the anchoring vegetation than a strict parabolic form.

From Textbooks • Jan. 1, 2017