Clouds and Dust Storms (Released 2 July 2004)

The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.
Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms. This image was captured 11 days after yesterday's image. The clouds that began as transparent water-ice have now developed into a full blown dust storm. The surface is completely hidden and the structure of the cloud tops is all that can be seen. These local North Polar cap-edge storms will continue throughout the rest of the spring.