The shape and size of cellular patterns within marine stratocumulus cloud layers
can change dramatically with the prevailing meteorological conditions. These
views from the Multi-angle Imaging SpectroRadiometer (MISR) provide an example of very
large scale closed cells, and can be contrasted with the small cells described
in an earlier image release. As described in that release, cellular structures
are associated with the sinking of air that is strongly cooled at the level of
the cloud-tops. This type of scene is fairly typical of mid-latitude oceanic
clouds unperturbed by cyclonic or frontal activity.
When the cell centers are cloudy and the main sinking motion is concentrated
at cell boundaries, the cells are referred to as “closed.” The cell diameters in
this image range from 40 to 100 kilometers (about twice the average size of
closed cells in general) and show an increased brightness at the cell centers,
giving them a mogul-like appearance. Because the cloud-top heights do not vary
substantially across the cells, the distinctive appearance is more likely due to
an increased concentration of cloud droplets at their centers.
The lefthand panel shows a part of the swath captured by MISR’s nadir
(vertical-viewing) camera on November 25, 2001, and is
displayed at a resolution of 1.1 kilometers per pixel (in the full-size image). The righthand panel highlights part of this scene at a resolution of 275 meters, and is centered at
approximately 49.2 degrees south latitude and 179.9 degrees east longitude,
covering an area of about 233 kilometers x 240 kilometers. The images utilize
data from blocks 123 to 135 within World Reference System 2, path 68.