Dust Storm over the Chryse Basin. These two pictures of a dust storm over the Viking lander site in the Chryse basin were taken 170 seconds apart. Motion of the clouds can be detected if the two pictures are viewed through a stereo viewer. Analysis of the two pictures indicates that portions of the cloud were moving from west to east with speeds ranging from 40 to 60 meters per second. This is consistent with westerly winds at the surface with the unusually high speed of 22 meters per second as recorded by the lander. The lander observation is, however, possibly in error because its wind sensor was damaged.
Source: NASA