Saharan dust: The good and the bad

The first large plume of Saharan dust is set to arrive in Florida. These tiny particles travel thousands of miles through the Saharan Air Layer (SAL), which is located between half and 3.5 miles from the surface. Sahara dust has been found in virtually all parts of the globe—even atop glaciers at or near both poles.

On average, a new plume or layer arrives in the Western Hemisphere about once a week or every other week, but their density can significantly vary.

NOAA started tracking the annual dust storms about 20 years ago. According to the National Weather Service, July 2024 was nearly 60%-70% dustier than usual, which made it rough for those with allergies. The plume was estimated to be roughly the size of the lower 48 in the United States, recorded as one of the larger Sahara Dust storms tracked.

Dust can mean hotter temperatures, which can be problematic for those with respiratory issues. However, it also suppresses tropical activity and provides plenty of nutrients for the largest rainforest in the world, the Amazon. Let's dust it all off!

The Bad

Most dust is between 5,000 and 20,000 feet in the atmosphere. But the particles eventually travel down to the surface, to the air we breathe in, and that’s where the respiratory issues can begin. Saharan dust can irritate people’s eyes, ears, noses, and throats. If you have allergies or respiratory health issues like asthma or chronic bronchitis, you may want to stay indoors and take your allergy medication.

When Saharan dust is present, temperatures tend to rise sharply. Dust particles absorb sunlight during the day, warming the air and reducing radiational cooling at night. This, in turn, can lead to higher minimum temperatures each morning. Since storms are very limited in the afternoons, there is no cooling, and the atmosphere is thoroughly warmed.

Lastly, the same nutrients that replenish the Amazon and Caribbean beaches also fall into the ocean. These same nutrients also feed the algae, which often collaborate in the production of red tide, which is mainly seen along Florida's coastline.

The Good

One big plus of the Saharan dust is that it suppresses tropical systems. Big, intense storms can usually fight off the dust, but weaker storms, or those not well defined, struggle to survive if dust particles are present.

The dust brings essential, limited nutrients to the Amazon rainforest, like phosphorus. Nutrients and minerals that travel thousands of miles are crucial to plant and phytoplankton growth on land and in the ocean, and they are vital for marine ecosystems.

Finally, hazy skies with more dust in the atmosphere make for brilliant sunrises and sunsets, typically lasting a few weeks. So, although it will be hotter when dust is present, make sure you go out and enjoy the sunset or sunrise. It will be extra beautiful!