A Saharan dust plume off the west coast of Africa is expected to blow into the Atlantic and Gulf of Mexico this week, suppressing storm development. For now.
The Atlantic plume, the largest of the 2024 hurricane season, will hinder tropical development from Africa to the Caribbean.
The natural event is known for stealing moisture from the air as sand, dirt and other dust from the North African desert area swirls into the atmosphere.
These plumes are common in the Atlantic basin around late June and early July, according to Michael Lowry, a meteorologist with WPLG-TV in South Florida.
What is Saharan dust?
Saharan dust consists of sand and mineral particles blown from the 3.5 million square miles of the Sahara desert in Africa.
Also called the Saharan Air Layer (SAL) by the National Oceanic and Atmospheric Administration, dust forms over the Sahara Desert during late spring, summer, and early fall.
Its dust clouds can travel and affect places around the globe, thousands of miles away from its African origin. Warmth, dryness and strong winds associated with dust clouds have been shown to suppress tropical cyclones.
Sahara dust has vivid sunsets, sunrises
In layman’s terms, because of the peculiar way Saharan dust scatters sunlight, the best times of day to spot it are usually a few hours after sunrise and late afternoon, according to the SAL website. During the day, the sky will have a hazy white appearance and sunsets will take on an orange glow.
Technically, white sunlight is made up of all the colors of the rainbow. Our skies are normally blue because the gases that make up the atmosphere naturally scatter blue hues (shorter wavelengths) as opposed to yellow-orange-red hues (longer wavelengths).
Sunsets and sunrises take on more yellow and reddish hues because low-angle sunlight passes through most of the atmosphere before reaching your eyes. A large dust load in the atmosphere can enhance this effect, leading to more consistent and darker colors that cause vivid sunsets and sunrises.
How does Saharan dust affect weather, climate and hurricanes?
According to the National Weather Service, there are three characteristics of these Saharan dust outbreaks that can affect tropical cyclones, tropical disturbances, and the overall climatology of the tropical Atlantic atmosphere:
- Extremely dry air: The dry, dusty air of the Saharan Air Layer has about 50% less moisture than the typical tropical atmosphere. This extremely dry air can weaken a tropical cyclone or tropical disturbance by inducing downslope around the storm.
- African Easterly Airplane: Strong winds in the Saharan Air Layer (25 to 55 mph or 10 to 25 meters per second) can significantly increase vertical wind shear in and around the storm’s environment. This “mid-level jet” of enhanced winds, typically found at an altitude of 6,500 to 14,500 feet (2,000 to 4,500 meters), can cause the tropical cyclone’s vortex to tilt with height and can disrupt the engine of inside the heat of the storm.
- Warm temperatures: The warmth of the Saharan Air Layer acts to stabilize the atmosphere, which can suppress cloud formation. This stabilizing effect is produced when the warm, buoyant air of the Saharan Air Layer passes over relatively cooler, denser air. The suspended mineral dust of the Saharan Air Layer also absorbs sunlight, which helps preserve its warmth as it crosses the Atlantic Ocean.
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Image Source : www.usatoday.com
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