HOUSTON – It’s that time of year again when we are tracking hazy skies and the culprit is none other than Saharan dust. This dust has traveled thousands of miles across the globe to our Texas skies...but what exactly is Saharan dust? Most know it lowers our air quality, but what are the positives of Saharan dust? We’ll be answering all below, and if you have more questions please send them in!
What is Saharan dust?
At it’s simplest definition Saharan dust is dust particles that originate from the Sahara Desert in Africa. These particles are made up of tiny specks of minerals, such as sand and soil. The Saharan Air Layer (SAL) is the layer of warm, dry, and dusty air that forms during the summer months. It extends vertically from the surface up to about three miles into the atmosphere and can travel thousands of miles. It impacts weather patterns, air quality, and even hurricane development. Let’s dive in!
Benefits of Saharan dust:
Limits tropical development: Hurricanes need moist, unstable air to form, similar to a thunderstorm. The Saharan Air Layer is dry and stable which inhibits the development or intensification of tropical storms. I like to visualize the Saharan dust like cedar chips. If you throw cedar chips on the floor, it will absorb the moisture. The Saharan dust does the same thing but in the air, it creates a very dry atmosphere that is not conductive for thunderstorms. If the layer of Saharan dust is thick enough it can also reflect some sunlight which lowers the water temperature.
Gorgeous sunrises and sunsets: When sunlight passes through the Earth’s atmosphere, it interacts with particles present in the air, such as dust, water droplets, and gases. The dust particles scatters sunlight, leading to move vibrant sunrises and sunsets, especially for red, orange, and pink hues (longer-wavelength colors). It is the same phenomenon to why smoky skies bring more vibrant colors at dusk and dawn.
Helps our marine ecosystem: As the Saharan Dust travels over the Atlantic Ocean some of the particles will be dropped on the surface of the ocean, including mineral nutrients, such as iron and phosphorus. These nutrients act as fertilizers, promoting the growth of phytoplankton at the surface. Phytoplankton are tiny, plant-like organisms that are at the the base of the marine food chain. More phytoplankton brings more food for all marine life starting from zooplankton to small fish, and eventually larger fish and whales.
Cons of Saharan dust:
Poor air quality: Saharan dust contains fine particles, known as particulate matter (PM), which can be inhaled into the respiratory system. These particles can be small enough to penetrate deep into the lungs, leading to respiratory issues, especially for individuals with pre-existing respiratory conditions like asthma or bronchitis. When inhaled the particles can cause irritation and inflammation in the respiratory system. This is why our air quality plummets with the dust.
Reduced visibility: Saharan dust can reduce visibility by creating a hazy or foggy appearance in the air. This can be problematic for transportation like airplanes as impairing visibility increases the risk of accidents.
Research on Saharan dust:
NOAA has a branch dedicated to studying the Saharan Air Layer. More satellites are contributing to a better understanding of how the SAL will impact us through the decades to come. For more on their research check out this webpage.