Saharan dust clouds reach Florida and the Atlantic coast. What is that?

Notice hazy skies in Florida?

It could be dust transported from the Sahara desert in Africa, to the southeastern states.

The movement of dry Saharan dust-filled air occurs every year, often reaching the United States just before Atlantic hurricane season. Last year, the dust clouds were expected to be seen in Florida in mid-June.

In addition to air pollution, other possible health risks include eye, ear, nose and throat irritation.

Palm Beach Weather:Storms, heat and Saharan dust could be expected over the weekend

NASA research breakdown:Will Florida see more or fewer of these annual storms?

See Monday’s dust forecast from NASA and the Global Modeling and Assimilation Office (GMAO), an organization that uses computer models and data assimilation techniques to improve Earth’s Earth observation program, below. The NASA.

NASA/GMAO - SEOS Prediction: Map of the optimal thickness of dust aerosols

What is Saharan dust?

Also called the Saharan Air Layer (SAL) by the National Oceanic and Atmospheric Administration, Saharan Dust is a very dry, dusty air mass that forms over the Sahara Desert in late spring, summer and in early fall.

Its dust clouds can travel and touch places all over the world, thousands of miles from its African origins. Heat, dryness, and strong winds associated with dust clouds have been shown to suppress tropical cyclones.

“SAL activity typically intensifies in mid-June and peaks from late June to mid-August, with new outbreaks occurring every three to five days,” said lead researcher Dr Jason Dunion. , a hurricane researcher at the University of Miami.

“During this peak period, it is common for individual outbreaks of SAL to reach farther west – as far west as Florida, Central America and even Texas – and cover large areas of the Atlantic.”

How does SAL influence weather and climate?

According to the National Weather Service, there are three characteristics of these Saharan dust outbreaks that can affect tropical cyclones, tropical disturbances, and the general climatology of the Atlantic tropical atmosphere:

  1. Extremely dry air: The dry, dusty air of the Saharan air layer contains about 50% less humidity than the typical tropical atmosphere. This extremely dry air can weaken a tropical cyclone or tropical disturbance by promoting downdrafts around the storm.
  2. East African Jet: Strong winds in the Saharan air layer (25-55 mph or 10-25 meters per second) can significantly increase vertical wind shear in and around the storm environment. This “mid-level jet” of enhanced winds, typically found at a height of 6,500 to 14,500 feet (2,000 to 4,500 meters), can cause the tropical cyclone vortex to tilt with height and can disrupt the engine. internal thermal of the storm.
  3. Hot temperatures: The warmth of the Saharan air layer acts to stabilize the atmosphere, which can suppress cloud formation. This stabilizing effect is produced when warm, buoyant air from the Saharan air layer passes over relatively cooler, denser air. The suspended mineral dust of the Saharan air layer also absorbs sunlight, which helps retain its heat as it crosses the Atlantic Ocean.

Saharan dust has vibrant sunsets

Short term… Due to the particular way Saharan dust scatters sunlight, the best times of day to spot it are usually a few hours after sunrise and in the late afternoon, according to the SAL website. During the day, the sky will take on a hazy white look and the sunsets will take on an orange glow.

Clouds reflect off a bright sunset in 2020 as dust from the Sahara moves near Satellite Beach, Florida.

Long-term… White sunlight is made up of all the colors of the rainbow. Our skies are normally blue because the gases that make up the atmosphere naturally diffuse blue hues (shorter wavelengths) as opposed to yellow-orange-red hues (longer wavelengths). Sunsets and sunrises take on more yellow and reddish hues because low-angle sunlight passes through more of the atmosphere before reaching your eyes. A heavy dust load in the atmosphere can enhance this effect, resulting in darker, longer-lasting colors that cause vivid sunsets and sunrises.

Saharan dust map today

From the Broward County Division of Natural Resources:

“Hello! The #AirQuality forecast for #BrowardCounty on Monday, May 23rd is MODERATE. This is due to Saharan dust and not uncommon at this time of year. Thanks to @NASA for the map below which gives us makes it easier to visualize this!”

South Florida:

Over the weekend, WPLG Local 10 meteorologist Brandon Orr (Miami) tweeted:

“Our first Saharan dust puff of the season went to South Florida.”

Grace Pateras is a digital producer for the USA TODAY Network. Follow her on Twitter at @gracepateras.

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