Wind Power T e Sahara is fi lled with many landforms. Yet one weathering and erosion force aff ects them all: wind. T e Arabic name for a wild, sand-fi lled wind is haboob. Other winds also have special names. Khamsin is an Arabic word meaning “50 days.” T is wind sweeps across the desert from March through May. It fi lls the air with sand. T e direction and strength of the wind


shapes the Sahara every day. Oſt en winds coming from the northeast reach hurricane speeds. T ey result in dense sandstorms and dust devils. During sandstorms, the wind stirs up


millions of grains of sand. At high speeds, wind-blown sand can strip the paint off of cars. T e sand doesn’t always stay in the Sahara. Giant sandstorms routinely blow all the way across the Atlantic Ocean.


Taking Shape Winds can change both the shape and the position of a sand dune. As the wind blows, it carries sand up one side of the dune and over the top. T e sand rolls down on the other side. Over time, this constant motion moves a dune slowly across the desert. Wind can also make distinct patterns.


A barchan dune has a crescent shape. It seems to have horns that point downwind. It forms when winds blow from the same direction for a long time. Seif dunes are long and narrow. T ey


develop when winds blow together from diff erent directions. A star dune has a central pyramid shape


with arms extending from it. Star dunes form in areas with lots of sand. Winds blow from several directions, piling the sand into a star shape.


A powerful sandstorm forms a wall of sand that whips across the landscape.


20


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24