Later this week, a large plume of Saharan dust that originated over North Africa is expected to reach parts of the Gulf Coast and Deep South. Not unusual for this time of year, the large dust plume will make for hazy skies and spectacular sunrises/sunsets, all while helping to keep tropical storm activity at bay in the Atlantic.
What is it?
Large plumes of Saharan dust are part of a grander atmospheric feature known as the Saharan Air Layer. As defined by NOAA, the Saharan Air Layer (SAL) is “a mass of very dry, dusty air that forms over the Sahara Desert during the late spring, summer, and early fall, and moves over the tropical North Atlantic every three to five days.”
The SAL is typically located between 5,000 and 20,000 feet above the Earth’s surface, occupying a 2-2.5 mile thick layer of the atmosphere. As activity peaks mid-June, the plumes of dust are transported by stronger easterly trade winds, which occasionally take the dust plume as far west as Texas (a +5000 mile journey from it’s original source).
What are the impacts?
There are both good and bad effects of these large plumes of Saharan dust.
— The dusty, dry air and strong winds within Saharan Air Layer are thought to suppress tropical cyclone formation in the Atlantic. Tropical storms need warm, humid air and light winds to grow and intensify… the opposite of the dry desert air these large dust plumes contain. Studies have shown that the SAL’s dry, dusty air has about 50% less moisture than the typical tropical environment. Also, strong winds of 25-55mph within these plumes (known as the ‘African Easterly Jet’) are said to increase wind shear, a change in wind speed with height, which works to shift and contort growing storms, tearing apart any ongoing or future tropical storm development
— Another positive is the spectacular sunrises and sunsets that come as a result of the SAL. These dust particles are located high in the atmosphere, helping to reflect and spread sunlight. This can give way to vibrant colors at sunset.
NOTE: We would love to see your sunset/sunrise photos! Upload your photos to us via KXAN’s Report It and be sure to include your name & location.
— Increased airborne particulates and dust can be irritating for those with allergies and respiratory conditions. Be sure to use caution while outdoors later this week/weekend (symptoms: itchy eyes, runny nose, sneezing, etc.)
— The dust creates a hazy sky, often times not the most beautiful nor scenic view.
For more information
For more information on the Saharan Air Layer, visit NOAA’s website here.