Did you see this image from Viking of a dust storm?
Here. Quite dramatic looking:
http://www.unmannedspaceflight.com/index.php?act=Attach&type=post&id=1886
Space/Science » in reply to re:They use RHU (Radioactive Heater Units)
Here. Quite dramatic looking:
http://www.unmannedspaceflight.com/index.php?act=Attach&type=post&id=1886