aslkahuna Posted May 15, 2011 Share Posted May 15, 2011 It is not a good year for Bouncing Castles. Another one in Tucson was taken out on Friday at a party in a city park. Some minor injuries due to flying debris but no one was in the Castle. This past week was a bad one for inflatable balloons as the FHU Aerostat broke its tether and broke up crashing in Sierra Vista. Strong winds at ridgetop level were a factor. A video of the demise of the Bouncing Castle was shown on weather.com. Steve Link to comment Share on other sites More sharing options...
Amped Posted May 15, 2011 Share Posted May 15, 2011 How do dust devils work. My best guess A week antural wind shift line moves over an area of hopt sand. As the wind picks up sand, the sand it heats the air enhancing the updraft. This increases the wind and the flux of warm sandy air into circulation. If this is true dust devils should never form at night and should dissipate quickly over forests. water, or wet sand. Link to comment Share on other sites More sharing options...
Crazieman Posted May 16, 2011 Share Posted May 16, 2011 They're strong little buggers sometimes. A few days ago I watched one take out a stop sign and bring it along a field several hundred yards Link to comment Share on other sites More sharing options...
aslkahuna Posted May 16, 2011 Author Share Posted May 16, 2011 Large devils can be as strong as EF1. Winds by Doppler have been measured as high as 97 mph in a dust devil. They are very interesting as they can show all forms of natural vortices including multiple vortex devils. Most are small but the big devils of Arizona/SE CA/NM/TX and other desert locations can be thousands of feet high and over 100 feet across. There is a misconception that you need hot air to form a devil but if that were the case then Mars would never get the big devils it does. What triggers a devil is the strong heating of the surface which sets up a strong thermal, as cooler air races in to replace the rising air of the thermal, surface roughness will result in the development of a surface whirl which can rotate either way. One interestign thing about AZ devils is that in recent years there has been video documentation showing that devils in close proximity to thunderstorm updraft bases can actually morph into landspout type tornadoes. Because devils depend upon surface heating to get going, they do not occur at night. They can be dangerous when large-we've had injuries this year and a man was killed in Maine by flying debris from a dust devil. Steve Link to comment Share on other sites More sharing options...
TimChgo9 Posted May 17, 2011 Share Posted May 17, 2011 Years ago, during a windy, hot summer day, a dust devil formed in the local park that my friend and I were hanging out in, and traveled about 200 feet before dissipating... it formed over the ball field at the south end of the park. It was active for about 45 seconds or so..maybe a bit longer... it picked up a couple of pieces of loose paper, but it was interesting to watch. It got no higher than the backstop for the ball field, if I remember correctly. I remember it being a hot afternoon, and while we were at the park, when the wind blew, little swirls would appear over the ball fields, and then dissipate right away. Before we saw the "big" one there were two or three short lived ones over the other fields, maybe lasting a few seconds. It was kind of weird watching it move across the grass after it formed over the baseball field. Link to comment Share on other sites More sharing options...
Amped Posted May 17, 2011 Share Posted May 17, 2011 Large devils can be as strong as EF1. Winds by Doppler have been measured as high as 97 mph in a dust devil. They are very interesting as they can show all forms of natural vortices including multiple vortex devils. Most are small but the big devils of Arizona/SE CA/NM/TX and other desert locations can be thousands of feet high and over 100 feet across. There is a misconception that you need hot air to form a devil but if that were the case then Mars would never get the big devils it does. What triggers a devil is the strong heating of the surface which sets up a strong thermal, as cooler air races in to replace the rising air of the thermal, surface roughness will result in the development of a surface whirl which can rotate either way. One interestign thing about AZ devils is that in recent years there has been video documentation showing that devils in close proximity to thunderstorm updraft bases can actually morph into landspout type tornadoes. Because devils depend upon surface heating to get going, they do not occur at night. They can be dangerous when large-we've had injuries this year and a man was killed in Maine by flying debris from a dust devil. Steve I was also thinking hot sand plays a role. The small size of sand grains (High surface area to volume) should make them good at rapidly transfering heat into the atmosphere. Link to comment Share on other sites More sharing options...
aslkahuna Posted May 19, 2011 Author Share Posted May 19, 2011 I was also thinking hot sand plays a role. The small size of sand grains (High surface area to volume) should make them good at rapidly transfering heat into the atmosphere. Yes, sandy soil helps as it does heat up fast. Also, it's easier to blow around making for some really photogenic devils. One great area for observing devils is along I-10 from the Divide to NM/AZ state line and especially near Lordsburg. There are large Playas (dry lake beds) in the area. Steve Link to comment Share on other sites More sharing options...
tacoman25 Posted May 19, 2011 Share Posted May 19, 2011 I saw a dust devil that lasted for about 15-20 minutes in eastern WA once. It was probably 150-200 feet high, maybe 6-8 feet across...pretty impressive, and it just meandered around in an area smaller than a football field. Link to comment Share on other sites More sharing options...
Amped Posted May 21, 2011 Share Posted May 21, 2011 I saw a dust devil that lasted for about 15-20 minutes in eastern WA once. It was probably 150-200 feet high, maybe 6-8 feet across...pretty impressive, and it just meandered around in an area smaller than a football field. The one I saw was in San Dunes National Park near Pueblo CO. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted May 23, 2011 Share Posted May 23, 2011 Dust Devils have always fascinated me. Is there any video of the recent dust devils? Link to comment Share on other sites More sharing options...
das Posted May 24, 2011 Share Posted May 24, 2011 Dust Devils have always fascinated me. Is there any video of the recent dust devils? Me too. Being an east coaster, when I went to school in Fresno, I was transfixed by them and, yes, was one of those idiots that would jump in the particularly aggressive examples I would "chase" through a dusty parking lot. There's lots of good examples on the net. Here's a fact page from Goddard and JPL's LIDAR study of dust devils in the AZ desert as they analyzed analogs to the martian dust devils they were seeing with the Spirit rover. http://www.nasa.gov/vision/universe/solarsystem/2005_dust_devil.html Link to comment Share on other sites More sharing options...
Mallow Posted May 24, 2011 Share Posted May 24, 2011 I saw a dust devil that lasted for about 15-20 minutes in eastern WA once. It was probably 150-200 feet high, maybe 6-8 feet across...pretty impressive, and it just meandered around in an area smaller than a football field. I was with my dad once down in the Salem area on a hot day, driving along dirt fields (fallow?), and there were scores of giant dust devils drifting this way and that. Probably at least 5 to 10 per field, most of which were over 100 feet high (some were probably several hundred feet high). Some were narrower (a couple feet across) while others were several yards across. Some seemed semi-permanent... like they were just meandering through the fields without showing any signs of weakening. It was pretty cool. EDIT: Kinda like this one, but that day they were moving much more slowly and somewhat more tightly-wrapped, in general... Link to comment Share on other sites More sharing options...
Bozart Posted May 26, 2011 Share Posted May 26, 2011 But it doesn't have to be sandy soil. Link to comment Share on other sites More sharing options...
k*** Posted May 26, 2011 Share Posted May 26, 2011 But it doesn't have to be sandy soil. That's awesome! I'd have to consider jumping into the middle of it. Link to comment Share on other sites More sharing options...
Bozart Posted May 26, 2011 Share Posted May 26, 2011 What the heck, let's chill the surface down even more: Link to comment Share on other sites More sharing options...
AppsRunner Posted June 7, 2011 Share Posted June 7, 2011 Saw a minor dust devil in a field off of Route 25 today. Actually picked up some twigs/leaves and tossed them around, but once it hit the road it collapsed. Was quite interesting to see, especially way up in Ohio. Link to comment Share on other sites More sharing options...
wall_cloud Posted June 7, 2011 Share Posted June 7, 2011 the primary factor in creating dust devils, as aslkahuna mentioned, is creating the thermal that stretches vertical vorticity. This can happen whether its hot or cold. you simply need cooler air above the surface to create said instability. I've seen a lot of dust/snow devils but that video of the devil over the water is a first. That video was awesome. Link to comment Share on other sites More sharing options...
tacoman25 Posted June 8, 2011 Share Posted June 8, 2011 But it doesn't have to be sandy soil. Wow, that thing gets fairly intense around the 30 second mark. I'd estimate winds at least 50-60 mph? But in an extremely small vortex lol. Link to comment Share on other sites More sharing options...
aslkahuna Posted June 8, 2011 Author Share Posted June 8, 2011 There's a classic video from years ago that shows a "hay devil" in New England. Steve Link to comment Share on other sites More sharing options...
AppsRunner Posted June 9, 2011 Share Posted June 9, 2011 There's a classic video from years ago that shows a "hay devil" in New England. Steve 1994: http://www.youtube.com/watch?v=4sGEaCto4-4 Link to comment Share on other sites More sharing options...
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