ST. LOUIS – A large plume of Saharan dust has made for some milky skies overhead this week.
It also can give us beautiful sunrises and sunsets as the dust intensifies the hues of reds and oranges we see. All light we see passes through our atmosphere.
“And depending on what’s in the atmosphere, interesting things can happen,” said Eric Gustafson, the Senior Educator at the St. Louis Science Center’s Planetarium.
As the sun rises and sets, the light we see comes from a low angle and has to travel through more atmosphere.
“The colors we naturally see during sunset, because of how blue light is effectively scattered by air molecules, are enhanced when you have large amounts of dust in the atmosphere that can intensify those oranges and reds. We typically see at sunrise or sunset,” Gustafson said.
Air currents carry dust from the Sahara Desert across the Atlantic.
While it can be beautiful at times, the extra dust in the air can be dangerous to those living with respiratory issues because it lessens the air quality, just like ozone and other ground-level pollutants.
“In fact, in the past, when we’ve had large amounts of dust from the Sahara Desert, it has led the scale to go beyond what they typically can measure,” said Gustafson.
This phenomenon is not unusual.
“It’s a pretty normal process. We certainly don’t get it quite to this extent,” said Gustafson. “But every year, around the end of May, June, July, dust from the Sahara Desert comes across the Atlantic Ocean, which is a very important process for other parts of the world as well.”
Another positive to the Saharan plumes is that they suppress hurricane activity in the Atlantic. The layer of warm, dry air caps the atmosphere, which inhibits moist air that is key to storm formation.
It also shades the ocean which can help keep sea surface temperatures down. The storms that manage to form tend to get ripped apart by the strong winds associated with the Saharan Air Layer.