The atmospheric pressure on Earth at sea level is about 1 bar. On Mars, the pressure is 6 to 10 millibars, or 1/100th that of our planet. But even in this atmosphere, wind still flows around obstacles.
In this image the ripples in the sand tell us which way the wind was moving and how it was diverted around these rock formations. (Typically the wind direction is perpendicular to the crest of the dune or in this case, the ripples.) [More at link]