Interesting finding: it's freezing inside a Tornado

Concordia researchers reveal why temperatures drop inside a vortex. CREDIT National Geographic Kids

Concordia researchers reveal why temperatures drop inside a vortex. CREDIT National Geographic Kids

Montreal, January 17, 2018 [sic] — With winter upon us in full force, outdoor temperatures are plummeting. But inside an intense tornado, it’s always chilly — no matter the time of year. A new study from Concordia proves why that’s the case.

In an article forthcoming in the Journal of Aircraftof the American Institute of Aeronautics and Astronautics, mechanical engineering professor Georgios Vatistas looks into the case of a violent tornado that touched down in 1955 in Scottsbluff, Nebraska.

During the storm, three broadcasters from the mobile unit of a local radio station were reporting live on the scene and had to take shelter in the basement of a stone building. There, as the tornado’s funnel passed overhead, they reported strange climatic changes. The temperature dropped from a mid-summer average, down to chilly, until the broadcasters were actually cold. They also found it difficult to breathe.

For 61 years, the cause of these phenomena remained unexplained. Enter Vatistas — a leading expert on the topic — who was able to formulate an analytical approach that allowed him to construct a new mathematical model of a turbulent compressible vortex.

To do this, he expanded on his previous theoretical developments on vortices to include the effects of turbulence and density variation.

“Using this new advanced approach, we were able to identify the cause of the temperature drop inside vortices for the first time ever,” says Vatistas, who conducted the study with recent Concordia master’s students Badwal Gurpreet Singh (MASc 14) and Rahul Rampal (MASc 14).

“As air pockets move from the outer periphery of the vortex toward its centre, the pockets expand, thereby bringing the temperature and density down.”

In the case of Scottsbluff, Vatistas and his team found that the temperature inside the tornado would have dropped from a comfortably warm background temperature of 27o C to a chilly 12o C. And at the tornado’s centre, the researchers estimated the air density would have been 20 per cent lower than what’s found at high altitudes.

“That’s what’s known as the ‘death zone,’ at 8,000 metres in altitude, beyond which mountaineers should not climb without breathing assistance gear,” Vatistas explains.

That’s why the reporters in Scottsbluff reported feeling deprived of oxygen. Luckily, the tornado passed quickly, and they avoided asphyxiation.

“It’s my hope that this important finding will help researchers better understand the many mysterious manifestations associated with violent atmospheric vortices like tornados and waterspouts.”

The study will also help engineers improve the operation of refrigeration vortex tubes, which are often used in the cooling of cutting tools during machining, various electronic components, hot melts, gas samples and heat seals.


Related links:

Cited study

Thermal Properties of Compressible Line Vortices

Georgios H. Vatistas*Gurpreet S. Badwal*Rahul Rampal

Concordia University, Montreal, Quebec H3G 1M8, Canada

*Professor, Department of Mechanical and Industrial Engineering; . Senior Member AIAA (Corresponding Author).

†Graduate Research Assistant, Department of Mechanical and Industrial Engineering.

Publication Date (online): January 11, 2017

A simple mathematical model to simulate the temperature, pressure, and density distributions in intense turbulent compressible line vortices is reported. Based on the previous n=2 member of the n family of vortices, a wider-range model that includes the rudimentary combined features of turbulence and compressibility is built. In antithesis to the previous laminar theoretical approaches, where the converging flow cooled down monotonically with decreasing radius, it is now discovered that, far from the axis of rotation, the gas is first heated up, reaching a static temperature maximum that is higher than the ambient value; then, it chills down to a subambient minimum at the vortex center. The cause of this effect is recognized to be the outcome of competition between two fundamental mechanisms: gas heating because of mechanical dissipation, and cooling due to mainly fluid parcel’s dilation. Thus, the present investigation identifies the cause of the Ranque–Hilsch-like thermal effect observed in unconfined compressible vortices. In comparison to laminar vortices, the center of a turbulent gaseous vortex is found to be cooler, thinner, and under lower-pressure conditions. All thermodynamic properties are shown to be functions of the vortex Mach number and level of turbulence.

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100 thoughts on “Interesting finding: it's freezing inside a Tornado

    • This is news? No one has even thought about this before?
      I have never studied the thermodynamics of tornadoes but it is obvious they are spinning fast and we know they suck stuff up and spit it out at high altitude: flying cows etc.
      This means that air at ground level is being sucked up at a very high velocity which implies a very high pressure gradient.
      We also know about centrifugal forces and if you centrifuge a gas you get low pressure at the centre. We also know about adiabatic cooling due to decompression.
      Now the it seems like there must be some serious achievement in getting a detailed mathematical model of all this work and give credible results. Kudos to the authors for that. But the rest seems pretty obvious just based on high-school physics.

    • “until the broadcasters were actually cold. They also found it difficult to breathe.”
      Sheesh, the answer is right there in front of them.
      It’s always been known that tornadoes have low pressure cores. Anything that spins that fast is going to have one.

  1. “…as the tornado’s funnel passed overhead, they reported strange climatic changes. ”
    *climatic* changes?? Oh, I seriously doubt that… Besides, within a tornadic vortex, there has been video of descending air parcels…which would be adiabaticly warming, not cooling.
    I would think this supposed phenomenon would have been something the past VORTEX projects would have experienced/observed.
    Just my $.02

    • Any adiabatic warming would be pressure dependent. The inside of a tornado is an extreme low pressure area so there is no adiabatic heating. Low pressures to the brink of asphyxiation and accompanying low temps are the resulting phenomena.

      • Seems like it gets cold and low pressure inside the venturi in my old carburetor.
        The Meredith Radiator tucked under the wing of every Spitfire that ever flew, including the prototype, cools the engine through expansion of air that is first warmed by the heat exchanger.
        The resulting thrust ( jet engine) completely overcomes the drag caused by having that box under the wing. So it was a net thrust.
        North American put the same gizmo under the belly of the P51. They think it was their idea. It was but they thought of it eight years or longer after K5054 was already flying.

      • george e. smith January 17, 2017 at 5:09 pm
        Seems like it gets cold and low pressure inside the venturi in my old carburetor.
        The Meredith Radiator tucked under the wing of every Spitfire that ever flew, including the prototype, cools the engine through expansion of air that is first warmed by the heat exchanger.
        The resulting thrust ( jet engine) completely overcomes the drag caused by having that box under the wing. So it was a net thrust.
        North American put the same gizmo under the belly of the P51. They think it was their idea. It was but they thought of it eight years or longer after K5054 was already flying.

        Well the radiator was named after its inventor F.W. Meredith from RAE Farnborough so it certainly wasn’t their idea! Here’s K5054 George:
        Note the radiator.
        The original P51 by North American couldn’t get out of it’s own way so the RAF had Merlin engines put in it which transformed it into a superb high altitude fighter. Since they were using the Merlin they also had the radiator with it, North American’s idea used an Alison engine in the original. The upgrade boosted the performance: horsepower from 1,200 to 1,620, top speed from 390 mph to 440 mph and service ceiling to almost 42,000 ft.

      • Thanks George. I looked into the Meredith Radiator. Interesting concept for the time. Thinking outside the box.

      • Well if you check my email tag which is seafang, you will find that was the last navalized version of the Supermarine Spiteful; the last Spitfire “variant”.
        Something like 235 seafangs were built for the Royal Navy, but after they were QA’d at the factory and passed as up to spec, they were just about all loaded onto trucks, and trucked over to the scrap metal yard, and never were flown. Something called “The Bomb” put an end to the need for more Spitfire models.
        You should be able to find a photo of the Seafang prototype, which had a five bladed prop on its Rolls Royce Griffon engine. Some of them had contra rotating six bladed props; somewhat weird looking.
        But the Spitfire narrow track undercarriage was not the greatest idea for a carrier aircraft, but surprisingly a lot of Spitfire mark 48s were used on carriers in the far east (post war).
        The P51 undercarriage folds in rather than out like the Spitfire. Somewhat odd that they used an outward folding plan when the Spitfire wing was known for being thin.
        There is some Seafang video on the web.

      • I don’t remember all this stuff. I have the special Spitfire 60th anniversary book that lists virtually everything that is known about the aircraft. And what isn’t in there is somewhere in the mountain of other books I have that do have it.
        And yes, I do know that they pinched the P51 belly radiator from the Royal Aircraft Establishment design. The original papers on the Meredith Radiator are in the spitfire 60th book, including all the thrust performance information.
        I always had a soft spot for wing leading edge radiators as used in the De Havilland Mosquito, and its son the De Havilland Hornet, which had contra-rotating mirror image engines (special Merlin 130/131 types) 2070 HP each, and more compact than a regular Merlin.

  2. If the funnel is a condensation cloud, then the temperature and pressure in the tornado vortex must be near the lifting condensation level. Lots of western tornadoes are visible only through dust they pick up, and have only a little tongue of a condensation cloud near the cloud base.
    J.R. Eagleman, a civil engineering professor at U of Kansas, applied compressible vortex theory to tornadoes in the 1970s. He got some outrageous estimates of maximum wind speed and central pressure drop. It would be nice to compare all these theories to measurements.

  3. Expanding gas can result in intense cooling. I read an accident report once which went something like this:
    A plumber used to freeze water in pipes by pointing his unlit propane torch at the pipe. That would effectively freeze and thereby turn off the water so he could work on the pipes. He did this while standing in a trench. Propane is heavier than air. I leave the result to you as an exercise.

  4. The tornado was in 1955, it is now 2017.
    It took them 63 years to discover that:
    Wait for it….
    Wait for it ….
    PV = nRT
    Wooo Hooo!!!
    ClimateScience! makes another great stride into the future!

    • It is not Pv=RT. It is cooling by adiabatic expansion. Both P and T vary during the process making the equation of state ambiguous. You need an additional relationship before applying the ideal gas law.

      • 1saveenergy, thank you.
        I was not aware of the ‘vortex tube’ before your post. Most impressive is that someone came up with the idea!
        Lots of good stuff in the comments on this thread. Inquiring minds need to know!

      • Ranque-Hilsch vortex tube tube refrigeration was used to cool railroad cars for decades before more modern methods. The engine provided abundant compressed air.

    • “Nice to know ‘climate scientists’ are finally catching up with engineering”
      No climate scientists involved here. This is an engineering prof writing in AIAA.

      • Very true, Vatistas is not a climate scientist. Whoever said he was should apologize. A Mann-esque defamation lawsuit might be pending.

      • We know Vatistas is an engineering prof, he did the study (that ‘climate scientists’ have never bothered / unable to do ), he mentioned vortex tubes near the end.
        What are you talking about ?
        Didn’t you read the artical ?

      • “Didn’t you read the artical ?”
        Yes, I did. And I found no mention of climate scientists. It isn’t climate science.
        I read the abstract too. There he cites Ranque–Hilsch thermal effects, referring to just the vortex tubes that you have depicted.

      • Nick , I immediately thought Hilsch vortex , too . Not heard Ranque’s name before .
        Always fascinated me that you could separate hot and cold molecules just by spinning them .

      • Later you’ll be claiming this article isn’t referencing climate, that the article isn’t about climate inside a gas vortex. You’re just wrong. There’s also the claim you’ll make that there are no climate scientists involved.
        Only the Aspberger challenged would try to claim what you said. It’s like a threaded needle of how wrong you can be almost every time you speak.
        FACE IT: your FRAUDULENT MOVEMENT has been REVEALED the FOLLY of FRAUDS. You hung your intellectual reputation on it and it’s been revealed – EVEN to the man on the STREET: as utter intellectual dross.
        “During the storm, three broadcasters from the mobile unit of a local radio station were reporting live on the scene and had to take shelter in the basement of a stone building.
        There, as the tornado’s funnel passed overhead,
        they reported strange climatic changes.
        The temperature dropped from a mid-summer average, down to chilly, until the broadcasters were actually cold. They also found it difficult to breathe.”

    • 1saveenergy,
      I am in partial agreement with you. The difference stems from the application of this well known principle to an “unconstrained vortex”. I played around with vortex tube cooling generators 35 years ago and we understood the mechanisms involved. This extension of the principle to unconstrained vortices demonstrate the same things happen in nature as the lab, or maybe the other way round.

    • Right. You can purchase vortex tube coolers to cool, for example, electrical cabinets in hot climates. My company uses them now and then but they require a lot of compressed air.

    • Ranque Hilsch effect was mentioned in the article. Far more refrigeration effect than simple adiabatic expansion and rivaling Brayton refrigeration cycle.
      Back to the side thread on the P51 Mustang and Spitfire…that thrust from the cooling system is called the Meredith Effect. The Mustang only suffered high altitude performance with the Allison as the turbosupercharger had a limited flat rating altitude. The same engine did fine in the P38. The Mustang was far more advanced than the Spitfire, using laminar flow wings and trapezoidal wing planform.

  5. I seem to recall having known that from decades ago.
    The rapid loss of pressure in the vortex reduces density via decompression and lowers temperature.
    This cannot be news, can it ??

      • That’s the nice thing about WUWT, lots of multi-disciplinary experience & all talking to each other & learning…..its how science & engineering used to work , until politicians & bean counters took over.

    • The air at the inlet of a gas turbine compressor (as used for electrical power generation and on jet airplanes) can be cooled by several degrees Celsius due to the intense suction at the inlet, which causes low pressure. Compressor bleed air is used to prevent icing.
      Older airplanes with piston engines and carburetors were subject to icing in the carburetor flow path caused by expansion cooling of the air. Pilots are still taught to suspect carburetor icing if the ambient temperature is below 75°F and the humidity is high.
      Stone-age tribes of South East Asia used the opposite effect, compression heating, for fire starters. They are called fire pistons and may have been using them since prehistory.

      • Carburetor icing is not JUST a result of air cooling due to a drop in pressure at the venturi. The other thing that happens is evaporative cooling due to fuel volatilizing as it enters the airstream in the venturi.

      • I remember one time I was in a plane taking off from the Seattle airport in the morning. I was sitting just forward of the wings and I could see vapor forming as it was sucked into the engines.

  6. Wouldn’t the vortex rapidly evaporate moisture creating cooling? Rain and hail are commonly part of the storm. Remember the highschool physics class where under a bell jar being evacuated, water in a watch glass began to boil and freeze at the same time? The mouth of the funnel would be vacuuming up moisture continuously.

  7. This may be a better model explanation, but somehow I don’t think it is either a new explanation or a new discovery. The internal low funnel pressure is what causes explosion rather than implosion of structures damaged by tornados. (Whereas hurricne damage is via implosion.) And PV=(nR)T is high school stuff. More hype by press release, it seems.

  8. Not suprised. After watching the white (i.e condensation) vortexes off the wingtips of landing airplanes and wondering why condensation is occurring it finally came to me. The spinning and widening vortex separates the air in the vortex from the air outside. This allows the expansion of the air in the vortex to be largely adiabatic, thus lowering the temperature in the vortex to drop, often below the dew point.

    • TPG, Very astute observation and analogy. Kudos. We have all seen that (well, before wingtip winglets reduced the vortex, since it is also wasted Energy drag).

      • I tried to leave a comment with the same picture a few hours ago. Could not isolate the url (?).
        Anyway, I have spent considerable time pondering the exact forces involved and have never found an explanation that I was content with.

      • Sorry eyesonu, my reply is in the wrong place (above here), basically you’re dealing with something called the Prandtl-Glauert singularity. “Near Mach 1, the Prandtl-Glauert singularity has amplified all pressure perturbations. As a result, the regions of expansion ( low pressure ) above the wings and cockpit correspond to much lower pressures than we would expect in an incompressible flow. As in other condensation problems, the lowered bulk pressure results in a lowering of the temperature causing condensation of the ambient water vapor.”

      • Phil,
        I don’t have time now but I will respond ASAP. If you have any links it would be greatly appreciated.
        The minute details have eluded me for years. I have cooked up my own theory but can’t mathematically substantiate it.
        Sincerely yours,

      • Phil, I have seen the exact same condensation around cars barrelling down the highway after some rain. At first you think the tires are just flinging up water from the road. But when you have the right temperature/humidity conditions and you study it closely, you can see the fog coming from in front of the wheels before it can get picked off the road.
        it is very common when I drive over the grapevine to LE during winter rains.
        Those are some cool pics you found there.

  9. Yes, drop pressure and temp tends to follow. As for tornadoes, I have been in the close proximity of several, and yes, after one passes the ambient temp tends to be lower.

  10. Tornadoes and cyclones are the result of the global electric circuit , and the way the atmosphere and Earth exchange energy. Swarm has discover that there’s a connection between the ionosphere and Earths molten iron Jetstream in the core . Looking down this road will give greater understanding to how foul weather systems form.
    Without electricity we wouldn’t be here.

  11. I machined up a Hilsch vortex tube one time. I followed the instructions in the Amateur Scientist column of the once-noble Scientific American magazine … sigh …
    It was amazing. It worked a treat. I got the cold end down to below 0°C.
    So I’m not surprised that it happens in an unconfined vortex. The interesting part of this news is that they’ve solved the math of the physical process. That’s always a huge step towards understanding.

    • Then why take the time to post a comment?
      So, uninteresting that you must post ad hominems without proofs, just displaying your animosity for all to read?
      Thank you.
      Now we know to skip your comments and to not bother following your links.
      Especially, since your comment reads exactly like fake advertisements and phishing spam.

      • Obviously a tube/cone with air rushing into it is going to have low pressure. A five year old child can realize that. Yet Anthony went his whole career and somehow managed to not realize that. His head is filed with the brain dead convection model–the marketing mantra of a brain dead paradigm. One can only wonder how the fact that storms, low pressure, and vortices are observationally correlated never inspires these zombies to question the validity of the vague, cartoonish, convection model of storm theory.

        • Gosh, because I run a press release verbatim because I found it interesting in the historical context of the Scottsbluff tornado you have concluded:
          1. You know what’s inside my head
          2. Five year olds are smarter than me
          3. I’m brain-dead
          4. I don’t understand the Bernoulli principle
          Well, two can play at that game. From your writing, I conclude that you’re a self-important asshole.
          Feel free to be as upset as you wish.

      • Meteorologists and climatologist have much in common. They hide behind the vagueness of their poorly understood, core beliefs.
        Tell us why you were surprised by this observation. Stop hiding. Address the freekin issue.
        Only if you are honest about what you don’t understand do you have any chance of breaking free from the stupidity you were taught in the earliest years of your education.
        What are you so worried about? Your reputation?
        We’ll all be dead in a hundred years.

      • “Claude Denkamonte January 18, 2017 at 4:05 pm
        Meteorologists and climatologist have much in common. They hide behind the vagueness of their poorly understood, core beliefs. ”

        You really mean you, Claude, fail to understand the simple words Anthony uses? Second grade words are too over your head.
        The article is about modeling winds in a tornado.
        Your straw man distraction statement regarding a tube/cone is not pertinent, nor are your ad hominems.
        And you are still phishing for traffic.
        Just another airhead troll ignorant of the difference between his backside and head, hoping to steer traffic to a website.

    • Gosh Claude, you come here to convince many that you are a pompous jerk,attacking Anthony for the “crime” of posting an interesting science/history based article for the PUBLIC to learn about.
      You can go away now,patting yourself on your back,congratulating yourself.

  12. A number of posts here state this is simply the application of the ideal gas law, Pv=RT, but there is more to it. A fast process of expansion in free air would be more like an adiabatic expansion. Since both T and P vary during the expansion, the ideal gas law produces an ambiguous result. A second relationship is needed, and usually we assume a reversible expansion obeying:
    Pv^k=Constant where k is the ratio of specific heats.

  13. Too bad they can’t figure out a way to cool molten slag before it drops on your crotch, burns a hole through your jeans and tighty whities, and says a hot hello to the family jewels, burning right through to the ground. It happened to a dear friend of mine.
    After running around the large piece of logging equipment he was field-repairing about 3 times he plugged the hole in his you know what with a rolled paper towel, finished the weld, then drove himself to the emergency room many miles away.
    And I am not making this up.

    • ! Whoa (ouch). That anecdote really sizzles. To take advantage of the cooling properties, I think getting your equipment repair job liked up with a tornado might be the tricky part.

    • OOHH!!! That smarts! I have had burn holes appear in a few spots, never that one. Worst one was lying under a trailer cutting an axle free on the side of an interstate hiway, 03:35. Remember cause I could see my watch as the glob fell from right beside it, onto my collar bone. Yowzer, did I come out from under there in a hurry. And no sympathy from stepdad, he just wanted to know why the axle was not loose yet.

  14. Where can I find a reference to air density being either that at 9 km or 20% less? The study is paywalled. At 9 km, a typical pressure is 350 mb and the temperature is generally well below zero. If air is at 12 degrees C while its density is typical of air 9 km above sea level, its pressure will be around 400 mb. Such low pressure (or 20% less) at Scottsbluff’s elevation of 3,891 feet is a very tall claim, and I would like a citation for such a tall claim other than a paywalled study. Average atmospheric pressure at that elevation is around 890-900 millibars, and the pressure could be around 870-880 millibars possibly as low as 860 in 27 degree C air at that elevation in a tornadogenic low pressure area. This means a pressure drop around 54%, which I consider an extremely tall claim for a tornado.
    Also, there is the matter of the amount of pressure drop that would reduce the temperature of air from 27 to 12 degrees C by adiabatic expansion. In a protected room during the time scale of a tornado passage, adiabatic expansion is essentially all that happens. This temperature drop is from 300 to 285 K, a 5% drop. The temperature change resulting from adiabatic compression or expansion follows the equation T2/T1 = (P2/P1)^((k-1)/k), where k is the specific heat ratio (ratio of the constant pressure value to the constant volume value), and for air k is close enough to 1.4. To reduce the absolute temperature of air by 5% using adiabatic expansion requires a pressure drop of about 16.5%.
    As for described effects: These sound like anecdotes from persons surviving a strong tornado, and this specific tornado is in the records as an F4. A 16.5% pressure drop easily explains F4 winds, even some F5 winds.

    • “Where can I find a reference to air density being either that at 9 km or 20% less?”
      Yes, it is a poorly worded and confusing claim. There is a paper
      here which measures a drop to 850 mb, which is much less than they claim here. However it may not be the biggest of tornadoes, and elsewhere there don’t seem to be many measurements. According to my lapse rate calculation, 150mb difference would make a 10°C drop in dry air, but a lot less in moist (1/(ρc_p) Δ P).

      • Yes, condensation is what counts. But it could be anywhere aline the gradient, basically between the core and ambient. I would expect that ambient was fairly humid, so in a transition from, say, 26°C to 12°C some condensation is likely.

      • As in, I remember being in Orlando at a pool one time and while wearing swim trunks a thunderstorm passed and it dropped from 90 to rain at 70 degrees F. It was freezing. No tornado though.

  15. You’ve gotta be kidding me!! I learned this in 1961 in my first aerodynamics course as a college sophomore. What is it with “scientists” that they have to pick subjects that were proved half a century ago and re-prove them.

  16. If you are inside a tornado and it is freezing, less than 0 C, your big problem isn’t the freezing. You are probably above 10,000 feet above ground. You better have a parashoot on if you want to land safely…

  17. A few years ago I was going out to dive on a reef off Key Largo when a waterspout came our way. Just before we abandoned the boat we were riding in to dive to the bottom the spout lifted over us, we actually saw clear sky up the middle of the vortex, and I remember it got really cold. I’ve been confused by that observation until now. The girl friend got her headlights turned on big time.

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