The storm moves forward like a rolling wall of black, brown, beige, or sometimes red, depending on the color of the earth and sand whirling about inside, often with a speed and height that terrifies everyone in its path.
It can be miles long, and several thousand feet high. It is a dust storm, haboob, black blizzard, black duster, and it is dangerous.
Dust storms moving at 100 mph have sandblasted homes, animals and people.
They obscure the vision of drivers causing accidents, injuries, death.
They infect animals and humans with eye diseases, meningitis, and Valley Fever.
According to recent research, including studies funded by the NOAA (National Oceanic and Atmospheric Association) Climate Program Office, the storms are increasing in frequency and intensity with changes in the earth’s climate creating that dreaded killer of crops, animals, humans, and even entire cities: Drought.
Anatomy of a Dust Storm
Dust storms became a symbol of the 1930s Dust Bowl era, but they are a common occurrence in the American Southwest, Australia, and in countries in the Middle East, areas that have high levels of sand or experience frequent drought.
According to David M. Ludlum, author of the National Audubon Society Field Guide to Weather, a dust storm is defined as “Wind-borne dust or sand lifted high enough above the ground (eye level or higher) to reduce horizontal visibility to 5/8 mile or less.” The contents within the dust storm can be local dirt and sand, or they can come from far away as dust storms often travel long distances depending on the wind or the strength of the storm pushing them along.
Dust Storm, Sand Storm, or Haboob?
There is also a difference between a Dust Storm and a sand storm, and the difference is quite logical due to the weight of the matter moving within the storm. Dust Storms can reach heights of 15,000 feet due to the light weight of the dust, whereas sand storms are generally around 10 feet high due to the weight of the sand and dirt particles.
David M. Ludlum further differentiates between Dust Storms and haboobs, stating that haboobs, a Sudanese name, originate in gust fronts passing over dry soil. Although dust devils are sometimes seen near dust storms, they are not the same.
Dust devils, tornado debris clouds and microburst dust clouds are not considered Dust Storms, because they are generally localized and brief.
Dust Particles and Wind Speed
Just as the weight of the material in the storm determines the height of the storm, it also determines the speed. The wind speed required to get that storm up and moving depends on whether or not the material on the ground is dirt, sand, dust, or a combination.
For instance, a mix of dust and sand, as one might find in central New Mexico can move along the ground pelting joggers, animals, and children if winds are 20 mph, but in order to reach eye level for classification as a dust storm the wind speed would likely be closer to 40 mph. Some dust storms have been tracked moving at speeds as high as 100 mph.
Decoding Science. One article at a time.