|Clouds over the (turquoise) Aral Sea|
NASA image MODIS on Aqua satellite, March 12, 2009
In the image above a series of waves spreads out over the Aral Sea, with the (left) boundary of the clouds conforming closely to the shape of the western shore of the Aral. As discussed in this NASA Earth Observatory post, clouds usually form when air rises over a mountain or other topographic high. Air cools as it rises, and moisture can condense out into clouds. When air flows down the other side of the mountain, it warms up and moisture evaporates, limiting clouds near the high axes of the mountains.
|Before and after as labelled. From Wiki.|
Because the lake has been shrinking, it is likely that the now-dry parts of the basin to the west are higher than the lake surface and causing the formation of the clouds. Changes in wind speed as the wind came across dry land to the west, where it would have been slowed by vegetation, and flowed east over the smoother lake, where it could accelerate may have contributed to formation of the waves over the lake.