Columns of dust are a natural phenomenon, part of the Earth’s nutrient cycle. They occur when high-speed winds pick up small dry particles from the Earth’s surface and transport them over long distances. Every summer, columns of dust from the Sahara desert in Africa cross the Atlantic Ocean.
They are generally not that large, and often sink into the ocean. But this one comes directly to America.
Sharp satellite eyes have been observing the plume as it developed and headed out to sea. ESA’s Copernicus Sentinel and Aeolus satellites have followed the progress of the plume. The plume is so large that it earned the nickname Godzilla.
The meteorological name for the plume is Saharan Air Layer (SAL). SAL is formed between late spring and early fall. Strong winds at the surface collect dust and transport it to the air and over the Atlantic Ocean.
If conditions are right, the dust can be transported to the upper troposphere and transported to the Caribbean or the United States, a journey of 8,000 km (5,000 miles).
Saharan dust cloud records go back about 20 years, and it ranks as one of the largest. It’s common for these dust feathers to make it to the U.S., but this one is remarkably large. NOAA says the plume is 60 to 70 percent larger than average.
The image below is from June 19, 2020. It is a composite image of the Copernicus Sentinel-5P satellite and the Aeolus satellite. The basecoat is a bright yellow 5P aerosol index and Aeolus aerosol cloud formation is placed on top.
Plume of desert dust over the Atlantic observed by Aeolus and Sentinel-5P. (THAT)
The Aeolus data is unique because it is the first satellite designed to acquire profiles of Earth’s winds worldwide. It helps build much more sophisticated models and forecasts, in part by determining wind heights more precisely. You can determine the height at which the dust layer travels, and in this image, Aeolus shows that most of the dust was 3 – 6 km (1.8 – 3.7 miles) above the ground.
Different space agencies now have a fleet of satellites that monitor Earth, and can closely observe things like this plume of dust. Each satellite can have a different combination of instruments, and together they give a more complete understanding of Earth’s atmospheric events.
Saharan powder feather on Sao Filipe. (Copernicus Sentinel / ESA / CC BY-SA 3.0)
Although its appearance in satellite imagery is prescient, the dust column could be good news. According to NOAA, these feathers can inhibit the formation of hurricanes. And it can also prevent those who are formed from becoming more powerful and destructive.
Dust is also a source of nutrients for phytoplankton, the small marine plants that float close to the ocean’s surface. Phytoplankton is central to the food web as it provides food for animals higher up the food chain. Phytoplankton is also photosynthetic, creating oxygen for the biosphere.
Dust feathers also replenish nutrients as far as the Amazon rainforest. Heavy and frequent rains there can deplete essential nutrients. Without these plumes, the Amazon is unlikely to exhibit such amazing biodiversity and lack such an intricate food web.
But there is bad news associated with the dust plume. Fog can trigger air quality alerts and can be a health risk, especially for people with underlying health conditions. This is in part because the dust has traveled so far that many of the larger particles have fallen to the surface. What remains are the smaller particles, which are more dangerous to people.
But for many people on the way to the plume, the part they will remember is the sunset. With all that dust in the air, the sunsets and sunrises will look stunning.
This article was originally published by Universe Today. Read the original article.
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