Hurricanes are among nature's most violent storms. It takes surprisingly little to break them up, and Saharan dust is one of the main culprits.
A classic model
Most of the Atlantic Ocean's most violent hurricanes originate from thunderstorms thousands of kilometers away, in the heart of Africa.
Thunderstorms over sub-Saharan Africa are at the origin of most of the tropical depressions and storms evolving into tropical cyclones that develop over the Atlantic at the height of the hurricane season, taking advantage of a favorable environment to grow from a modest disturbance into a fearsome monster.
However, even if the continent serves as a cradle for the most violent storms, another hazard blowing in from the coast can just as easily neutralize a budding hurricane before it has a chance to blossom.
The Sahara is the world's largest hot desert. It covers almost a third of the African continent, with sand dunes and some of the hottest temperatures the climate can produce. Moving southwards from the Sahara, the climate gradually changes from desert to tropical, with summer monsoons bringing almost daily thunderstorms and heavy rain.
Violent thunderstorms regularly form near this transition zone and move westwards towards the continent under the influence of prevailing winds. These tropical waves make their way to the eastern Atlantic Ocean, where they slowly develop into tropical cyclones that swirl around the basin.
Saharan air can kill a nascent hurricane
Dry, sand-laden winds frequently blow off the Sahara desert during the summer months, throwing huge clouds of dust across the Atlantic Ocean. Each puff of hot, dusty air blowing across the continent is known as a Saharan Air Layer (SAL). These features can greatly disrupt hurricane development and even fill the skies over North America with haze and dangerous air quality.
A significant intrusion of Saharan dust over the tropical Atlantic Ocean can alter the environment to the point of stifling the development of tropical cyclones.
The high concentration of dust in the air can reflect sunlight and cool the environment. These desert winds are also very dry, depriving tropical cyclones of the moisture they need to develop and thrive. The combined effects of lower temperatures and drier air can deprive existing storms of the ingredients they need to survive, and the hostile environment cripples tropical disturbances before they have a chance to develop.
Fig. 1; Source: NASA
Saharan dust may affect North American skies
In the summer of 2020, a large plume of dust from the Sahara desert reached the skies over the Caribbean and the southern United States. tats-Unis, considerably affecting air quality throughout the region and giving rise to extremely colorful sunsets for several weeks.
High concentrations of dust are dangerous to breathe, especially for children and adults suffering from chronic illnesses such as asthma. Dust particles are so tiny that they easily penetrate the lungs.
Dust puffs migrating from the planet's scorching deserts can also have beneficial effects. According to NASA, the minerals contained in the dust can fall into the oceans and onto the ground thousands of kilometers away, fertilizing the waters and soils to the benefit of life in these bountiful ecosystems.
