Health & Science

Here’s Why Dust From The Sahara Desert Is Turning The Houston Sky Yellow

Why are parts of the Texas sky yellow and what does this mean?

Residents in parts of Houston and East Texas woke up Thursday morning to find the sky yellow. Although it may look like pollution, it’s actually caused by small particles of sand that have traveled from Northern Africa. Here’s what you need to know about the Sahara dust, or Saharan Air Layer, as it’s formally called. 

What is it?

The dust comes from the Sahara Desert in Northern Africa. Each year, hundreds of millions of tons of soil is lifted from the Sahara into the air, according to NASA. It’s not uncommon for this dust to change the color of the sky several times throughout the summer, while trade winds move north and take particles from the Sahara into the Gulf of Mexico. 

The dust itself is composed of sand and other mineral particles, according to researchers from Texas A&M’s Department of Atmospheric Sciences, who analyzed NASA satellite images and computer models in July of 2018.

[Video by NASA’s Scientific Visualization Studio / NASA Center for Climate Simulation]

Who will it affect?

People with respiratory illnesses, such as asthma and allergies, will likely see flare ups in their symptoms.

How long will it last?

“It’s maybe not as strong as has been noticed in past days, but it’s still there and it does look like it is heaviest north of Houston,” said Sean Luchs, a meteorologist with the National Weather Service. He says the cloud is mostly on the way out, though things could change. 

What does this mean for Texans?

Research suggests dust clouds like this one can actually lower the intensity of hurricanes in the Atlantic because the air is so dry. The 2019 hurricane season is projected to be near-normal, with El Niño conditions in the Pacific also keeping activity suppressed. 

Texas A&M Professor of Atmospheric Sciences Renyi Zhang said in a press release that the chances of a hurricane forming tended to be much less and “our results show that dust may reduce the occurrence of hurricanes over the Gulf of Mexico region.”

“Dust may decrease the sea surface temperature, leading to suppression of hurricanes,” he said. 

This June 21, 2009, file photo from the NASA Earth Observatory shows Saharan sand blowing off the coasts of Mauritania and Senegal. Although this image shows dust immediately off the coast of West Africa, a layer of dust from storms such as this often travels virtually intact to the other side of the Atlantic. This layer of dry, hot, dusty air is called the Saharan Air Layer.

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