What is the Saharan dust layer? What it means for hurricanes, weather in Florida
Saharan dust is back! A plume of dust carried by the wind all the way from the Sahara Desert is traveling thousands of miles through the atmosphere and is expected to skim over south Florida this week.
During the late spring, summer and early fall, bursts of dust from the Saharan Desert are picked up by wind and form a big mass of dry, dusty air that sits about a mile up in the atmosphere at its lowest point.
This mass of dry, dusty air is called the Saharan Air Layer (SAL), and its activity ramps up from mid-June through mid-August, when it moves over the tropical North Atlantic Ocean every three to five days.
'During this peak period, it is common for individual SAL outbreaks to reach farther to the west — as far west as Florida, Central America and even Texas — and cover extensive areas of the Atlantic (sometimes as large as the lower 48 United States),' NOAA's guide to the Saharan Air Layer says.
This layer of dust can be good for keeping the tropics calm during hurricane season, but it can also affect people with allergies or respiratory issues.
Here's what Saharan dust is, when the next plume is expected in Florida and how it affects hurricane formation.
The Saharan Air Layer (SAL) is a yearly phenomenon in which plumes of dust from the Sahara Desert are picked up by the wind and 'ride' it across the ocean, being carried thousands of miles west.
'SAL outbreaks can form when ripples in the lower-to-middle atmosphere, called tropical waves, track along the southern edge of the Sahara Desert and loft vast amounts of dust into the atmosphere,' NOAA says.
'As the SAL crosses the Atlantic, it usually occupies a 2 to 2.5-mile-thick layer of the atmosphere with its base starting about 1 mile above the surface. The warmth, dryness and strong winds associated with the SAL have been shown to suppress tropical cyclone formation and intensification.'
When it's present in the atmosphere, Saharan dust can make the sky look hazy and bring vibrant sunrises and sunsets.
The most recent plume of Saharan dust has yet to hit Florida, but is expected to sometime late Friday night, according to FOX 13 Tampa Bay.
'The first rounds of Saharan dust are set to sweep over Mississippi and the Gulf Coast this weekend and in the first week of June. They'll keep coming all summer,' the Mississippi Clarion Ledger reported on Wednesday, May 28.
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When Saharan Dust mixes with rain, it makes "dirty rain."
Like Saharan Dust, 'dirty rain' isn't toxic or dangerous, but can irritate you if you have pre-existing respiratory issues. 'Dirty rain' is just dust mixed with water and can leave a muddy residue behind on any exposed surfaces it falls on.
You might remember the news talking about Saharan Dust and "dirty rain" in July last year.
'For Floridians, Saharan dust has helped quiet storm development in the Atlantic Ocean during the first half of the 2024 Atlantic hurricane season,' the Pensacola Journal reported on July 22, 2024.
While Saharan dust helped keep the first part of the 2024 hurricane season fairly calm, it didn't set the tone for the latter half of the season, which brought several major, devastating storms to the southeast late in the season.
While there is Saharan dust present in the tropics, it has the power to stop new storms from forming and weaken already-existing storms. This is because tropical storms need warm, wet air to thrive and the dryness of the SAL undercuts the ideal conditions needed for storms to form and thrive as it passes over the Atlantic.
Other than impacting the tropics, Saharan dust can also affect people with allergies. Since the Saharan Air Layer brings dry, dusty conditions, people with allergies might see a flare up when Saharan dust reaches Florida. The presence of extra dust and dryness in the air can irritate or inflame any existing allergies or respiratory issues you might have, like asthma.
If you want to minimize the amount of mud or dust you inhale or have a pre-existing respiratory issue, avoid spending a lot of time outside or wear a face mask if you're out for an extended amount of time.
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This article originally appeared on Fort Myers News-Press: Saharan coming to Florida: How it affects hurricane season
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