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Clouds over Meridiani - Sol 956 (GIF-Movie)
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NASA's MER Opportunity captured a view of wispy afternoon clouds, not unlike fair weather clouds on Earth, passing overhead on the Rover's 956th Sol (such as Oct. 2, 2006). With Opportunity facing North-East, the clouds appear to drift gently toward the West in this movie taken with the Rover's NavCam.
The 10 frames, taken 32" apart, show the formation and evolution of what are likely mid-level, convective water clouds. Such clouds are common near Mars' Equator at this time of the Martian year. They have been observed by both of NASA's MER, by satellites orbiting Mars and by the HST. In this case, the clouds appear to develop at a fixed location, in the center of the frame about 25° above the horizon. This style of origin suggests that a thermal plume is rising over a surface feature. In spite of apparent winds aloft, the thermal plume appears to remain stationary for the whole duration of the movie.
Though scientists have determined from the images that the wind bearing is East/North-East, approximately 80°, it is not possible on the basis of the movie to unambiguously determine the height and speed of the clouds. Scientists estimate, based on models of atmospheric wind profiles and the apparent displacement of the clouds, that all of the clouds in the movie are at about the same height somewhere between 5 and 25 Km (about 3 to 20 miles) above the surface. The clouds are estimated to be moving at 2,5 mt per second, if they are low, to 12,5 mt per second, if they are high (8 to 41 feet per second).
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