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Massive Cloud Of Dust Is Moving From The Sahara Desert To North America


It's a journey that's taken weeks and spanned thousands of miles across an ocean, floating on currents of air. Today a massive cloud of dust from the Sahara Desert arrives in the southeastern United States. To walk us through this meteorological phenomenon, we are joined by professor Marshall Shepherd, the director of the Atmospheric Sciences program at the University of Georgia. Welcome.

MARSHALL SHEPHERD: Thank you for having me.

SHAPIRO: OK. Now, I've seen the satellite images, but tell us what it's going to look like from the ground as this wave of dust from the Sahara arrives in the United States.

SHEPHERD: You know, we get these things every year, and some are bigger than others. These are, this year, quite large, and so I think that's why it's garnering so much attention. Typically, you lose the blue sky for a more hazy, milky sky. You tend to see more vivid sunsets and sunrises because of the scattering properties of the dust interacting with the sunlight. So those are sort of the optical effects. But I think people that suffer from allergy to dust or particulate matter - they actually might not find it so amusing. They may have some health issues.

SHAPIRO: Why is it so much bigger this year than normal?

SHEPHERD: I think one thing that happened this year, Ari, is that that dust in the Sahel region and in parts of Africa sat there and just collected because the wind system - this African easterly jet that meteorologists talk about - it took a bit longer to kind of get itself going. And once it gets itself going, it can belch and burp that dust out into the Atlantic, and that's what we're seeing now. But because there was somewhat of a delay, there was a lot more dust sitting there that built up.

SHAPIRO: All right, so pros - you said good sunrises and sunsets. Cons - people who have health problems might find that their respiratory problems are worse. What else is this dust system going to do? I mean, on the whole, is it a good thing or a bad thing?

SHEPHERD: You know, one of the things as an earth scientist - the Earth is so connected, and this is just another example. So these dust storms, they actually can fertilize the oceans in parts of Amazonia. They're carrying things that really help those ecosystems. But on the flipside of that, there've been studies recently that say they can actually carry pathogens as well. So when you think about mosquitoes as a vector-borne disease carrier, some have argued that these dust storms can be vectors. They can carry pathogens. Another perhaps positive, however, is that the dust - if there were to be a hurricane forming out over the Atlantic, hurricanes don't like this dust. If the dust gets into those forming systems, they can weaken those storms quite a bit.

SHAPIRO: How much bigger is this one than what we would see in a typical year?

SHEPHERD: You know, it's interesting. I saw a colleague tweet a scale. They were using some data from NASA. NASA has several satellites up monitoring air quality and air constituents. And literally, this event was off the chart. It wasn't even the same type of event. It was just so far off the plot scale.

SHAPIRO: And so for people who study atmospheric science like you, is this a moment to totally nerd out and, like, remember where you were when the great Sahara dust storm of 2020 came across the Atlantic?

SHEPHERD: I think it is. I mean, I've seen some sort of very hyperbolic terms like the Godzilla's dust storm and those types of things. I don't tend to like use such hyperbole when I talk about these things, but it is an anomaly event. My good friend and colleague Tom Gill at the University of Texas El Paso is an expert on dust storms. I know he's geeking out on this. You know, I host a podcast called "Weather Geeks" for the Weather Channel, and we use the term geeking out. I'm certain that scientists like Tom Gill are geeking out over this dust storm.

SHAPIRO: Marshall Shepherd is the director of the Atmospheric Sciences program at the University of Georgia and former president of the American Meteorological Society. Thanks for talking with us about this monster dust storm.

SHEPHERD: Thank you for having me.

(SOUNDBITE OF BLITHE FIELD SONG, "CLASPED HANDS") Transcript provided by NPR, Copyright NPR.

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