Clouds over Meridiani (natural colors) - Sol 956

Like clouds on Earth, these Martian clouds are probably composed of ice crystals and possibly supercooled water droplets. They are similar in appearance to terrestrial cirrocumulus or high altocumulus clouds. On Earth, such clouds are relatively transient and consist of small, individual cloudlets arranged in rippled patterns. They usually form 6 to 12 Km (about 4 to 7 miles) above Earth's surface by a process known as convection, during which warm air rises and cools, with clouds condensing from the moist air once it has cooled sufficiently.

These Martian clouds appear to be associated with a broader layer of ice-crystal clouds fanning out toward the upper right of the frames at the end of the movie. This is similar to the occurrence of terrestrial cirrocumulus and altocumulus clouds within layers of cirrus or cirrostratus clouds on Earth.
Also apparent in this movie are prominent waves in the clouds, a result of the effect of gravity waves on cloud thickness, as on Earth.

Though both Rovers now have the ability to autonomously detect clouds, these images were taken prior to the first use of the new abilities. The images shown here were stored on Opportunity and were transmitted to Earth on Sol 1056 (such as Jan. 12, 2007) during a routine communications pass.