John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
Grime wafting across the ocean from the Sahara is predicted to reach Houston today.
Temperatures in Texas today might resemble those of the Sahara Desert, with heat-index values in Houston as extreme as 108. But that’s not the only similarity between the regions: A vast cloud of desert dust incoming from Africa is expected to hit Texas between now and Friday, potentially coating cars and windows with red grime and creating excellent sunsets.
The Saharan plume was moving over Mexico yesterday and could reach southern Texas today, according to the National Weather Service:
The floating grit isn’t likely to trigger any health issues, but could cause haze and spread an alien, red hue across the skies at dawn and dusk. Here’s more about such wandering dust from NOAA:
Consisting (mostly) of tiny pieces of metal oxides, clays, and carbonates, dust is the single largest component of the aerosols in Earth’s atmosphere, and it likely has a significant impact on the Earth’s climate, as it effects a wide range of phenomena, including from temperatures in the Atlantic Ocean to the rate of snowmelt in the southwestern U.S. Dust may also affect hurricanes, as recent research based on data sets dating back to the 1950s suggests an inverse relationship between dust in the tropical North Atlantic and the number of Atlantic hurricanes during the past several decades….
And speaking of the Sahara, Lake Chad, which sits just below it in the north-central part of Africa, is the Earth’s largest single source of atmospheric dust. In fact, about half of the dust suspended in Earth’s atmosphere originates in North Africa, due to both the abundance of dust sources there and the region’s position under the subtropical jet stream, which carries dust around the world. The rest is said to come from just a handful of other well-known dust-producing regions, including northwestern China’s Taklimakan Desert, parts of Arabia, Iran, the shore of the Caspian Sea, the Lake Eyre Basin in Australia, and the area around Utah’s Great Salt Lake.