Saharan Air Layer

Dust in the Saharan Air Layer off Western Africa.

The Saharan Air Layer (SAL) is an intensely dry, warm and sometimes dust-laden layer of the atmosphere which often overlays the cooler, more-humid surface air of the Atlantic Ocean. In the Sahara Desert region of North Africa, where it originates, it is the prevalent atmosphere, extending from the surface upwards several kilometers. As it drives, or is driven, out over the ocean, it is lifted above the denser marine air. This arrangement is an inversion where the temperature increases with height. The boundary between the SAL and the marine layer suppresses or "caps" any convection originating in the marine layer. Since it is dry air, the lapse rate within the SAL itself is steep, that is, the temperature falls rapidly with height.

Saharan Air Layer Media

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  Dust off Western Africa in 2020

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  Images showing Saharan dust crossing the Atlantic

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  Dust particles can be seen as far as Cuba

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  Lithometeor at sun set in Berlin on 25 February 2021, cloudless sky with Saharan Air Layer.

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  Vivid sunset during the arrival of the Saharan Air Layer in Northern Mexico.

Other websites

• NOAA FAQ: Saharan Air Layer
• Real Time SAL data
• HA! Look at 2006! Where are the Hurricanes?
• Research: Aerosols Slow Wind Archived 2007-02-05 at the Wayback Machine