Dust devils
May 18th, 2009 at 4:19 pm by Matt Kirkwood under Weather
I did a little research for Joe LaFurgey to add to his story about the dust devil that hit Lincoln Nursery in Standale. He mentioned that a few eyewitness accounts said they saw railroad ties briefly lifted in the air along with various other debris.
My research suggests that most wooden railroad ties weigh between 120 to 140 pounds. Quite an impressive feat for a Michigan dust devil!
What causes dust devils? Well, in nearly every picture that you see of a dust devil the sky will be crystal blue with full sunshine. A light-to-nearly calm wind is also favorable for dust devil formation. This creates an ideal set up for strong heating of the air near the ground. Also, keep in mind this time of year when the sun angle is very high/strong. The end result is a highly unstable atmosphere at lower levels.
Dust devils typically initiate along the intersection of varying surface types, such as asphalt and dirt or a dirt road and a crop field. Once the thermal of air starts rising, the air near it rushes in to replace the initial updraft. So you will have a spiral of hot air swirling upwards with cooler air descending in the middle. The air rushing in to replace it will pick up any loose materials, such as dirt and leaves. Dust devils can range in size to 5 to 100 feet in diameter and have wind speeds from 10 to 70 mph.
On the Enhanced Fujita Scale, nearly all dust devils would be ranked an EF0 with winds less than 85 mph. Most last only a few minutes with the largest being sustained as long as a half an hour or more. The circulation of a dust devil starts at the ground and goes upward as opposed to a tornado where the circulation is derived from mid level winds that descend from the parent storm to the ground.
Glendale Community College in Arizona posted information about Dust Devils, and some recent damage was caused by a strong dust devil in Las Vegas.
Interesting post Matt,
I remember about 10 years ago driving through eastern Washington on US 2. We were surrounded by dust devils. We could see 30 or more surrounding us. They were going over the road and out in the fields. It was hot and dry. Pretty cool thing to see.
I had no idea this kind of thing happens in Michigan. I have seen them in Phoenix and Tuscon while visiting my sister, but thought that they were a desert thing. Thanks for the info!
I took some neat video in 2002 of a huge dust devil as it danced over the fields of Gettysburg (PA) National Military Park, at the site of Pickett’s charge. As Matt described, it was a bright-blue, cloudless sky with almost no wind.
On a beautiful clear day in Big Rapids about two weeks ago I was sitting in my side yard and saw a bunch of leaves and twigs going around in a fairly tight, perhaps 15 feet, circle. I could hear a strong wind but it wasn’t blowing hard where I was 100 feet away. This dust devil moved across the yard and when it hit my deck it moved a chair a little bit, dropped a bunch of debris on the deck and vanished behind the house.
For what it’s worth I have a small lake and the dust devil seemed to be following the shore before it headed for the house.
I have seen small Dust devils before, nothing too big. Looks like they can do some damage.
There was a big dust devil at the 2006 B93 Birthday Bash. It went right through the middle of the Ionia fairgrounds and lifted a tent up into the air for quite a while. Good times!