This past weekend brought with it a huge plume of Saharan dust from the western coast of Africa. With incoming rainstorms, that thick layer of dust, which has nearly fully enveloped Florida, could cause what meteorologists are calling “dirty rain.”
Saharan dust is kicked up into the atmosphere this time every year. The phenomenon is nothing new, though it has been more widely talked about as forecasters’ ability to monitor plumes has improved — along with their understanding of potential impacts.
The size of the plumes range. This year, a plume has traveled over 3,000 miles from Africa and spread across the entire Gulf of Mexico. In 2020, an historic Saharan dust storm made its way across the Atlantic that contained 182 million tons of dust.
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Meteorologists expect potential thunderstorms could mix with the layer of dust, which typically sits between 1-2 miles into the atmosphere, to create “dirty rain.”
What is dirty rain, and will Pensacola be impacted? Here’s what we know.
What is Saharan Dust?
Saharan dust, also referred to as the Saharan Dust Layer (SAL), are outbreaks of dust from the Sahara Desert that have been kicked up about a mile into the air from topical waves in the Atlantic.
The layer of dust is about 2 to 2.5 miles thick, according to NOAA, and consists of warmth, dryness and strong winds that carry it westward over the Atlantic to North America. When plumes get large enough, it can impact the lower 48 states.
For Floridians, Saharan dust has helped quiet storm development in the Atlantic Ocean during the first half of the 2024 Atlantic hurricane season. More good news? It should drop slightly drop temperatures over the next week or so.
What is ‘dirty rain’?
Dirty rain isn’t really a technical term. It’s just a way to describe the effects Saharan dust will have on rain as it falls through the layer of dust hanging overhead. The ultimate effect will be dirty cars, streets and, well, that’s about it.
Dirty rain isn’t expected to be any more dangerous than what the Saharan dust brings, which is the potential for minor respiratory issues. Anyone with pre-existing respiratory issues should avoid spending heavy amounts of time outside and wear a face covering when they’re out and about.
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Is Saharan dust dangerous?
Reading the description, it could be easy to let the mind wander, picturing cities in the U.S. blanketed in a thick smog of dust, but its visible effects aren’t quite as dramatic. Given how high in the atmosphere the dust sits, it can create vibrant sunsets and sunrises due to the way it scatters sunlight. During the day, at most, the sky could have a hazy white appearance if there are large enough quantities.
Health-wise, there is usually little reason to worry as the SAL rarely carries all the way over to the U.S. When it does, its effects would be similar to any other type of dust. People who already experience underlying lung conditions are at increased risk of complications.
According to the American Lung Association, wheezing and coughing could be indications that you’re experiencing elevated levels of dust exposure. To protect yourself, you should stay indoors and wear a face covering if you have to go outside.
Will the Pensacola area see ‘dirty rain’?
A plume of Saharan dust is expected to pass over Pensacola on Wednesday, which is expected to see a couple of showers and thunderstorms, according to AccuWeather.
How does Saharan dust impact hurricanes?
Tropical development requires warm water and wind. Tropical disturbances tend to form in waters around the equator where ocean temperatures can reach the 80-degree minimum required to begin developing. When wind moves over these warm bodies of water, it causes water to evaporate from the surface of the ocean.
That vapor then rises, cools and condenses into large water droplets, which create cumulonimbus clouds. When the warm vapor cools, the heat energy is dispersed at the top of the clouds, making the air pressure higher, which in turn pushes the lower air pressure down to the ocean’s surface to repeat the pattern.
The dry Saharan dust can curb these conditions a bit by stealing the moisture and disrupting the pattern.
This article originally appeared on Pensacola News Journal: ‘Dirty rain’ in Florida forecasted. Will Pensacola be impacted?
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