Saharan air layer
The Saharan air layer (SAL) is an extremely hot, dry, and sometimes dust-laden layer of the atmosphere that often overlies the cooler, more humid surface air of the Atlantic Ocean. It carries upwards of 60 million tonnes of dust annually over the ocean and the Americas.[1] This annual phenomenon sometimes cools the ocean and suppresses Atlantic tropical cyclogenesis.[2]
The SAL is a subject of ongoing study and research. Its existence was first postulated in 1972.[3]: 1330
Creation
The dust cloud originates in
Disturbances such as large
Sometimes a depression to the southwest of the Canary Islands increases the wind speed and intensity of the SAL, which can lift the dust around 5,000 metres (16,000 ft) into the air and often carries the dust as far as the Caribbean.[6]
Effects
The SAL passes over the Canary Islands where the phenomenon is named "
From northern Africa, winds blow twenty percent of dust from a Saharan storm out over the Atlantic Ocean, and twenty percent of that, or four percent of a single storm's dust, reaches all the way to the western Atlantic. The remainder settles out into the ocean or washes out of the air with rainfall.[citation needed] Scientists believe the July 2000 measurements made in Puerto Rico, nearly 8 million tonnes, equaled about one-fifth of the year's total dust deposits.[citation needed]
The clouds of dust SAL creates are visible in satellite photos as a milky white to gray shade, similar to haze.[citation needed]
Findings to date indicate that the iron-rich dust particles that often occur within the SAL reflect
See also
References
- NOAA FAQ: Saharan Air Layer
- Real Time SAL data
- SAL over the Atlantic, current graphic display
- Research: Aerosols Slow Wind
- HA! Look at 2006! Where are the hurricanes? (SAL role in delaying hurricane season)