- Education and Science
Did You know that some of the beach sand in Florida actually comes from the Sahara Desert?
It's true. African dust has been blowing over the Atlantic Ocean since the ice ages. The summer months in the Earth's Northern Hemisphere allow for incredibly dry air over the Sahara, allowing for Saharan dust to blast up high into the atmosphere and travel incredibly long distances. In this article we'll explore the Sahara Dust event, when and why it happens, and where most of this sand is likely to land. We'll also look into an interesting theory that ties Florida's gulf coast's "Red Tides" to the Sahara Desert!
During the Northern Hemisphere's summer months, almost every day Sahara Desert sand blows up into the atmosphere and out across the ocean, most of which falls on the Caribbean, but some of which makes its way to Miami and even all the way across the Floridian peninsula! In fact, much of the dust in the topsoil of the Caribbean, from many generations of sand and dust storms, can actually be traced directly back to Africa!
The layer of sand and dust that is blasted up into the air is actually known as the "Sahara Air Layer" or SAL. The layer forms in the late Spring, Summer, and early Fall and gets pushed into the Atlantic almost every day.
The picture above was a snapshot of June 28, 2012. You can find the 5 day real time map of the SAL here. Most of the time, if the dust actually makes its way all the way to Miami, it is barely noticed. The sky may seem a bit "Hazy", and the sunsets might be spectacular, especially filled with the color red. When a significant amount of dust and sand makes its way to Miami and the rest of the Florida coast, it will leave a light coating of reddish-brown dust on your car. The reddish brown colored dust dropped by the Saran Air Layer comes from the large amount of Iron found in the Saharan desert dust.
Red Tides caused from the SAL?
"Red Tide", an algae bloom that kills fish and stinks up the everywhere around the beaches it effects, have been happening quite recently in Florida, and many like to blame man made pollution as the source of the problem. But... Red Tides have been occurring (at least publicly known about) and recorded for at least the last 200 years....
There's a theory by a few scientists that the "Red Tide" may actually be caused by the Sahara Air Layer! You see, Red Tide is actually an algae bloom. An algae bloom that feeds on nitrogen.
As it turns out, Florida has a microorganism called the Trichodesmium. The "Trich" feeds off of Iron in the air, and turns it into nitrogen....plenty of nitrogen to feed Red Tide Algae! "It's like fertilizing your lawn. " says John Walsh, PhD, Distinguished Research Professor, University of South Florida. You can read more about his study HERE. Or for more information visit FloridaEnvironment.com
Basically, his theory is that the more Saharan dust that lands along the Florida coast (east and west), the higher the chances of a RED TIDE event.
More Iron = More Trichs = More Nitrogen in the Ocean = Higher chance of Red Tide event.
And, since Saharan Dust has been blowing over the Atlantic ever since the Ice Ages, it stands as a more reasonable cause of Red Tide than pollution.
The next time your walking along the Florida coast, pick up a handful of sand, and ponder where it actually might have come from. Oh, and FYI - the Sand blows in both directions. In the 1930s sand from the American Dust Bowl blew along the westerlies and made it all the way to London!