From the link provided below:

However, Waw al-Namus and its plume are not the only "wind records" in the area. As you utilise higher resolution images - of the order of 1 km or better, other, somewhat different "long-term wind tracers" are revealed at almost every place across the Sahara Desert. These generally take the form of small-scale, long, parallel thin lines, as if being drawn across the desert by a giant pencil. One of the most spectacular places with long-term wind streamlines imprinted into the landscape can be found further southeast of Waw al-Namus, to the southeast of the Tibesti Mountains.

http://oiswww.eumetsat.org/WEBOPS/iotm/iotm/20060115_wind/20060115_wind.html