North Polar Cap

This image shows an example of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed catabatic winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sea level, the wind speeds increase. Catabatic wind speeds in the Antarctic can reach several hundreds of miles per hour.
In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker, layered trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime.
The horizontal lines in this image are due to framelet overlap and lighting conditions over the bright polar cap.