This article is a Deal Alliance summary of an article by By Umair Irfan written for VOX.
The giant dust storm, called the Saharan Air Layer (SAL), that emanates form the hot Saharan desert cloud is part of a system that has, among other ecological advantages, the ability to suppress hurricanes if conditions are right. This year in June, those conditions were unprecedented. The air mass was enormous and fast-flowing.
What is the SAL and how does it form?
On the boundary between the Sahara desert and the Sahel there is an ancient dry lake bed called the Bodélé Depression. The Bodélé Depression is a giant dust bowl which gets whipped up to a height of 10,000 feet and forms an area of desert dust during the summer months. This is called the Saharan Air Layer (SAL). In June this year, this convectivly generated airmass reached a height of 20,000 feet above ground.
With the assistance of the West moving trade winds, the SAL drifts off the coast of West Africa, moving across the North Atlantic Ocean every three to five days from the late spring through to the early fall. It then dissipates most of the dust as critical mineral additions to the surface of the Atlantic ocean before reaching the coast of the Americas.
What was different about the SAL during June 2020?
During June his year, the SAL was particularly large, high, hot and fast-moving. Furthermore, it managed to hold together all the way across the Atlantic ocean to inject extremely hot, dry air deep into the tropics where hurricanes tend to form. This has the effect of reducing hurricane intensity.
The hurricane-suppressing action comes not from the dust itself but from the hot, dry air that carries it. Hurricanes feed off moist air while dry air impedes hurricane development y shutting down the deep convection pattern at the core of the storm.
Who is interested in the SAL?
The SAL phenomena is of great interest to different areas of science for various reasons. Metoerologists study it for indications of climate change, environmental Agencies for air pollution, and the medical world for dust as a possible vessel for viral and bacterial diseases from other continents.
Marine biologists will also keep a close eye as they watch for the impact of less dust settling on the Atlantic ocean and more reaching and fertilizing the Amazon rainforest, while an artist or photographer would look forward to experiencing spectacular sunsets when the atmosphere is heavy with dust.
This an important environmental phenomenon with far-reaching consequences that also plays an important role in so much of life on earth.