Saharan dust has pros and cons

The season’s first plume of Saharan dust is arriving in the Caribbean from across the Atlantic, bringing beautiful sunsets and hazy skies. When clouds of dust billow off West Africa, they form what meteorologists call the Saharan Air Layer.

The annual peak period of the Saharan Air Layer, which started in West Africa at the start of the year, is now at its peak.  This layer floats at altitudes between 5,000 and 15,000 feet. If the layer is dense enough, it can smother an emerging tropical storm like a blanket on a fire. Some of the dust is rich in iron and phosphorus, so when it lands in the ocean, it acts like a fertilizer for phytoplankton.

The plume hoists so much dust into the skies that some of it ends up in the south-eastern United States. Its particles are so fine they can enter your bloodstream and trigger asthma and allergies. While Barbados is typically the first land mass Saharan dust reaches, the particles often travel further, even reaching the United States’ Gulf Coast, as witnessed recently.

Activity typically intensifies around now until mid-August, according to the National Weather Service. The Individual Saharan dust plumes have reached Florida, Central America and the Caribbean during the peak period and can even cover most of the Atlantic and the US.

While the current dust plume should bring seasonal concentrations of dust to the tropical Atlantic, it’s largely underwhelming so for this time of year.

So far in May and June, outbreaks of Saharan dust have been at record lows throughout the tropical Atlantic going back at least 20 years, which has contributed to the exceptional ocean heat wave across the north Atlantic this summer.

The Saharan Air Layer is a mass of dusty and dry air that can be up to 2.5 miles thick and can start hovering at just 1 mile above the earth’s surface.

A plume of Saharan dust moved into Cuba and The Bahamas recently. The pretty sunsets are formed when dust particles from the plume make the sky erupt in more vivid colours like orange, pink, and red during sunrise and sunset. They last longer, too.

Another positive of Saharan dust is that it helps keep tropical activity down. Its warmth, dryness, and strong winds typically suppress hurricane development and intensification. More specifically, it’s extremely dry air weakens tropical disturbances and hurricanes by promoting downdrafts around the storm. Its warmth helps suppress the formation of clouds, too.