SIOUX FALLS, S.D. (KELO) — Dust in the wind can travel thousands of miles, according to researchers and the World Meteorological Organization.
In general, “the smaller the particle the more it can travel,” said KELOLAND News meteorologist Scot Mundt.
The wind in South Dakota may not carry dust particles thousands of miles but dust will travel.
The U.S. Department of Agriculture studied how the wind blows dust in a field. Scientists measured the levels of dust in suspension from a small field containing sandy lamp soil after eight different dust storm events.
The study concluded that 30-foot wide vegetation buffer strips did not capture much of the dust. An average of 34% of the total dust was deposited within 600 feet of the eroding field. Another 30% was deposited about 150-feet away and only 12% to 15% fell within 30 feet.
What’s in that blowing dust?
Dust can contain dirt, sand, and small bits of rock and gravel.
Dust can also contain hair, bacteria, smoke, pollutants and other materials.
“There are two types of dust in the atmosphere, both kicked up by high-velocity winds in dry areas. Fine dust tends to lead to cooling because it scatters sunlight, much like clouds do. Coarse dust, which is larger and originates in places such as the Sahara Desert, tends to warm the atmosphere, much like greenhouse gases,” said an April 2020 news research story shared by the National Science Foundation .
Why does the wind blow so much?
Sioux Falls, Aberdeen, and Pierre have their average wind speeds peak in April, Mundt said.
But the wind was blowing long before April.
“The reasons behind the wind the past several months can be due to fast moving systems from the northwest (known as clippers),” Mundt said. “These usually bring a quick hit of light snow as well as strong winds. But, much of the snow has been deposited in central Minnesota and north while much of South Dakota has been dry. This sets us a big temperature gradient (change) between the snow-covered ground and the bare ground. This also results in plenty of wind. Once these clippers pass, they have northerly winds, so the dominant wind direction has been from the north.”
The average wind speed at 33 feet above sea level in South Dakota is 12.8 mph. At 328 feet above sea level, it’s 20.3 mph.
Various data analysis rank South Dakota as the sixth most windy state in the U.S. Wind energy industry analysts also list South Dakota as having high wind energy production potential.
Often, it seems, the wind may be stronger in the western part of the state.
Land features bring about the stronger winds in western South Dakota,” Mundt said. “As the cool, dry air descends from the Hills to the plains of western South Dakota it picks up speed and warms (also known as compressional warming). Also, lack of trees cuts down on surface friction there’s nothing to slow it down as winds race in from the north or south.”
NOAA has this explanation for why we have wind: Warm air rises and leaves low pressure pockets behind it. Cold air sinks.
“Gases move from high-pressure areas to low-pressure areas. And the bigger the difference between the pressures, the faster the air will move from the high to the low pressure. That rush of air is the wind we experience,” NOAA says.
National Geographic has more: “Winds generally blow from high-pressure areas to low-pressure areas. The boundary between these two areas is called a front. The complex relationships between fronts cause different types of wind and weather patterns.”
Who pays attention to the wind?
Scientists pay attention to the wind and the stuff that blows around in it.
But so do contractors, farmers and the wind energy industry.
GX, the Grading and Contractor website and magazine, discussed “Working With Dirt When the Wind Blows” in a January 2000 post.
“Microscopic soil particles can carry such noxious materials as heavy metals and bacteria, endanger motorists and pedestrians by reducing visibility on roads, and irritate our noses, throats, and lungs,” the GX post said.
The post discussed ways to reduce disturbed soil and dust at construction sites.
The Indiana Contractors website has advice for contractors who work in high winds, including if they are at elevated levels or on the ground.
“Do not schedule work at elevations on days where high winds are forecast,” is one guideline.
Another is “Keep a clean work site. Don’t leave cones, signage and other loose materials laying around and unsecured. A gust of wind could pick up a scrap of material and send it flying.”
The wind industry pays a lot of attention to wind speeds.
Wind turbines can produce power with wind speeds of about 6 mph. The rated power rate is around 26 mph to 30 mph. The cut-out speed is about 55 mph.