Dusty

WTF is going on with the massive Saharan dust cloud coming to the US

2020 is getting even crazier.

A plume of dust that once blanketed the Sahara Desert is making its way across the Caribbean and, soon, into the United States.

The so-called "Godzilla dust cloud" is the largest of its kind in the past 50 years, scientists say. It's expected to reach states near the Gulf Coast — including Texas, Louisiana, and Florida — by Wednesday or Thursday this week.

Along with dust, the cloud is expected to bring varied effects. Because dust in the air can spur or worsen respiratory issues, experts are concerned about the effect the dust will have on health.

At the same time, in the long-term, the plume may be helpful in tampering the effects of hurricanes.

By itself, an influx of dusty air from North Africa isn't unusual — it happens every year, ramping up around mid-June and lasting through the early fall, reports NASA's Earth Observatory.

Known as the Saharan Air Layer, this dust plume is often visible from space as it blows west over the Atlantic Ocean. Roughly 800 million metric tons of dust make the journey each year, usually filling a two-mile-thick layer of the atmosphere, starting about a mile above the ground.

Horizontally, this year's plume stretches about 1,500 miles at its widest parts, NASA reports. You can watch the plume travel in (almost) real-time on the Colorado State University website.

This year the incredible size of the cloud has come as an unexpected — and potentially dangerous — surprise. Because the African Easterly Jet, an important lower troposphere feature over West Africa that transports dust westward, was weak this June, experts believe a larger amount of dust was able to accumulate.

“This is the most significant event in the past 50 years,” Pablo Méndez Lázaro, a professor of environmental health at the University of Puerto Rico, told the Associated Press. “Conditions are dangerous in many Caribbean islands.”

Breathing dusty air — This year's dust outbreak has already swept over Puerto Rico, Dominican Republic, and Barbados.

Experts are particularly concerned for the safety of people with respiratory symptoms tied to Covid-19, AP reports. NASA is working on an alert system to notify people when the dust is at concerning levels, and scientists warn that even healthy people could be at risk.

At a time we're already advised to wear masks for our health, the dust cloud gives reason to take extra precautions. Experts are warning people in the most affected areas, including the Caribbean islands, to stay indoors and use air filters.

Conditions in the Caribbean could begin to clear up later this week, thanks to a small tropical wave moving toward the region.

Ecology of dust outbreaks — It goes without saying that breathing in a ton of dust isn't good for human health. But this large swath of dry air may have some helpful effects, too.

Air from the Saharan Air Layer can "help suppress the development of tropical systems," like hurricanes, according to the National Weather Service.

Ecologically, the dust plays another important role: It fertilizes soil in the Amazon and beaches in the Caribbean.

Nutrients in the Amazon, mostly coming from decomposing plant leaves and other organic matter, can be scarce. The abundance of plants soaks them up quickly, and some nutrients like phosphorus get washed away by heavy rainfall. Sometimes, this nutrient spike has negative effects, like harmful algal blooms.

Bright skies — One positive side-effect that's likely to come immediately: naturally filtered sunsets.

In a process known as scattering, particles (like dust) in the air cause sunlight rays to change course on their way to the Earth. That causes a more vibrant appearance.

This week, the skies in parts of the southern US may appear a brighter orange, red, pink, or bluish-purple because of this scientific phenomenon.

It makes one wonder if this is what Joni Mitchell referenced in her 1971 song Carey: "The wind is in from Africa / Last night I couldn't sleep."

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