Strong winds frequently whip up dust as they funnel through a break in the Tibesti and Ennedi massifs and across the Bodélé Depression, the lowest point (land elevation) in Chad. By one estimate, dust storms cloud the skies over the ancient lakebed roughly 100 days each year.
On January 20, 2021, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the NOAA-20 spacecraft captured striking imagery of one of those storms. The image above shows dust from the Bodélé streaming through the gap in the mountains as it rides northeasterly winds.
The dust itself is mostly comprised of particles of quartz and the remains of ancient diatoms—microscopic organisms that lived in ancient Lake Mega Chad. About 7,000 years ago, the lake spanned an area larger than all of the Great Lakes combined.
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Image via NASA Earth Observatory