On the Electromagnetic Basis of Tornadoes.
Tornadoes are a devastating natural phenomenon, currently beyond our ability to predict or control. However, science marches on… Diligent scientists have tried for many years to connect the dots between the electrical properties of supercell thunderstorms and tornadogenesis. New measurements of electromagnetic waves could indicate they were on the right track.
The history of electrical theories for tornadogenesis goes back quite a ways. There have been many anecdotal reports of luminous phenomena (most likely of an electrical nature) associated with tornado formation.
In one instance, a fisherman was greeted by a surprise funnel cloud and claims to have witnessed the inside of the tornado. There was an apparently violent outer vortex and a more orderly inner vortex inside which many bolts of lightning were seen.
January 21, 1992. Near Cripple Creek, Colorado. Shortly after 2 PM, while fishing at Skagway Reservoir, D. Mc Gown spotted an ominous cloud formation developing in the west. A horizontal, black cloud rolled toward him. Suddenly, it lifted to reveal a huge, twisting funnel advancing directly at him. He threw himself to the ground, but got a good look up into the interior of the funnel.
“The outside of the tornado was spinning so fast my eye couldn’t follow it, but the inside was rotating almost lazily. I could see a thousand feet up inside it. Tiny fingers of lightning lined the hollow tube.”
Passing over him, the funnel bounced across the lake, ripped up some trees, and was gone.
(McGown, Dennis; “Letters,” Time, 147: 8, June 10, 1996)
The double-vortex seems quite reminiscent of the description of an electrically-motivated “charge sheath vortex” surrounded by a more chaotic “turbulence” or “shear” vortex, as proposed by Peter Thomson, from the UK.
In another instance, one R.S. Hall claims to have gotten a good look at the inside of another tornado funnel and was awed by what he saw, including a long bright central cloud that shimmered like a fluorescent light. Is it possible that the same mechanism used in fluorescent lights (a “glow discharge” in plasma) was at play inside the tornado?
May 3, 1943. McKinney, Texas. People rarely get the chance to look up into the funnel of a tornado and live to tell about it. R.S. Hall did; and what he saw is very strange.
“The bottom of the rim was about 20 feet off the ground, and had doubtless a few moments before destroyed our house as it passed. The interior of the funnel was hollow; the rim itself appearing to be not over 10 feet in thickness and, owing possibly to the light within the funnel, appeared perfectly opaque. Its inside was so slick and even that it resembled the interior of a glazed standpipe. The rim had another motion which I was, for a moment, too dazzled to grasp. Presently I did. The whole thing was rotating, shooting past from right to left with incredible velocity.
“I lay back on my left elbow, to afford the baby better protection, and looked up. It is possible that in that upward glance my stricken eyes beheld something few have ever seen before and lived to tell about it. I was looking far up the interior of a great tornado funnel! It extended upward for over a thousand feet, and was swaying gently, and bending slowly toward the southeast. Down at the bottom, judging from the circle in front of me, the funnel was about 150 yards across. Higher up it was larger, and seemed to be partly filled with a bright cloud, which shimmered like a fluorescent light. This brilliant cloud was in the middle of the funnel, not touching the sides, as I recall having seen the walls extending on up outside the cloud.
“Up there, too, where I could observe both the front and back of the funnel, the terrific whirling could be plainly seen. As the upper portion of the huge pipe swayed over, another phenomenon took place. It looked as if the whole column were composed of rings or layers, and when a higher ring moved on toward the southeast, the ring immediately below slipped over to get back under it. This rippling motion continued on down toward the lower tip.”
Hall also reported a peculiar bluish light and blue streamers that appeared to consist of vapor. (Hall, Roy S.; “Inside a Texas Tornado,” Weatherwise, 40:73, 1987.)
Another observation included what was most likely a nighttime tornado emitting a noticeable internal glow:
At 0448 GMT, following a sudden cessation of rainfall, M.D. Smith became aware of an orange glow outside his window. Accompanying it was a roar like that of a military jet. The phenomenon occurred a total of four times; the second of which is the most interesting.
“A second illumination was observed twenty seconds later, but this time it reappeared away from the tree so a clear view was possible. The illumination was in the form of a narrow column and of the classic gentle ‘S’ tornado shape in the ‘roping out’ stage; it was silvery in colour towards the top and golden-orange lower down. Additionally, Mr. Smith saw the illumination move from the sky towards the ground, but at a speed slower than lightning. The sound of rushing wind was heard again, while this illumination lasted five to six seconds. Mr. Smith also noted a very low cloud base with a second layer of cloud only slightly higher.”
(Reynolds, David J.; “Nocturnal Tornado Illuminated by an Electrical Discharge at Farnham, Surrey, 10 January 1994,” Journal of Meteorology, UK, 20:381, 1995.)
Another historical anecdote, provided by no less than the NOAA, provides two independent accounts of laying claim to the witness of internal tornado dynamics, including a “central cloud,” constant internal lightning, smaller tornadoes forming at the base of hte larger tornado and making a screaming / hissing sound.
Mr. Will Keller, a farmer of near Greensburg, Kans., is the man to whom reference is made, and the following is substantially his story:
It was on the afternoon of June 22, 1928, between 3 and 4 o’clock. I was out in my field with my family looking over the ruins of our wheat crop which had just been completely destroyed by a hailstorm. I noticed an umbrella-shaped cloud in the west and southwest and from its appearance suspected that there was a tornado in it. The air had that peculiar oppressiveness which nearly always precedes the coming of a tornado.
But my attention being on other matters, I did not watch the approach of the cloud. However, its nearness soon caused me to take another look at it. I saw at once that my suspicions were correct, for hanging from the greenish-black base of the cloud was not just one tornado, but three.
The family had entered the cellar and I was in the doorway just about to enter and close the door when I decided that I would take a last look at the approaching tornado. I have seen a number of these things and have never become panic-stricken when near them. So I did not lose my head now, though the approaching tornado was indeed an impressive sight.
Steadily the tornado came on, the end gradually rising above the ground. I could have stood there only a few seconds, but so impressed was I with what was going on that it seemed a long time. At last the great shaggy end of the funnel hung directly overhead. Everything was as still as death. There was a strong gassy odor and it seemed that I could not breathe. There was a screaming, hissing sound coming directly from the end of the funnel. I looked up and to my astonishment I saw right up into the heart of the tornado. There was a circular opening in the center of the funnel, about 50 or 100 feet in diameter, and extending straight upward for a distance of at least one half mile, as best I could judge under the circumstances. The walls of this opening were of rotating clouds and the whole was made brilliantly visible by constant flashes of lightning which zigzagged from side to side. Had it not been for the lightning I could not have seen the opening, not any distance up into it anyway.
Around the lower rim of the great vortex small tornadoes were constantly forming and breaking away. These looked like tails as they writhed their way around the end of the funnel. It was these that made the hissing noise.
I noticed that the direction of rotation of the great whirl was anticlockwise, but the small twisters rotated both ways — some one way and some another.
The opening was completely hollow except for something which I could not exactly make out, but suppose that it was a detached wind cloud. This thing was in the center and was moving up and down.
The tornado was not traveling at a great speed. I had plenty of time to get a good view of the whole thing, inside and out.
I am not the first one to lay claims to having seen the inside of a tornado. I remember that in 1915 a tornado passed near Mullinville and a hired man on a farm over which the tornado passed had taken refuge in the barn. As the tornado passed over the barn, the door was blown open and the man saw up into it, and this one like the one I saw, was hollow and lit up by lightning. As the hired man was not well known, no one paid much attention to what he said. [Mr. Keller thought that this tornado was the one shown in photograph opposite p. 448 of MONTHLY WEATHER REVIEW of 1919.]
Mr. Keller is a man apparently between 35 and-40 years of age. His reputation for truthfulness and sobriety is of the best. Apparently he is entirely capable of making careful and reliable observations.
With so much anecdotal evidence on the side of an electrical interpretation, it seems like scientists should jump at the opportunity to study these phenomena from an electrical perspective. However, electrical studies of tornadoes seems to be spotty in the literature at best. Perhaps that will change soon, considering a recent “revelation” released via an article in New Scientist magazine. It seems that some scientists are now actively taking the electrical study of tornadoes seriously and believe that it may just revolutionize the study and prediction of the same. Though they didn’t explicitly say it in so many words.
Tornado hunters may have a new, unlikely ally – electricity. Armed with only an antenna mounted on top of a vehicle and a simple receiver, researchers have been able to pick up low-frequency electromagnetic waves – a possible sign that a tornado is brewing. The frequency of the signal should even be able to tell them the ferocity of the storm.
The team – Ernst Schmitter from the University of Applied Sciences Osnabrueck in Germany and his colleague, John Leeman from the Leeman Webb Storm Laboratory – picked up the signals while investigating a type of rotating storm known as a “supercell”.
Supercells are characterised by heavy wind, rain, and hail, along with a vortex of swirling air several kilometres wide. About 30% of these spinning storms spawn tornadoes as the vortex descends towards the ground. Schmitter and Leeman say that it is this swirling action that generates the electromagnetic radiation.
The researchers believe that if this study pans out it may make for a safer and more reliable method of determining storm behavior and when a tornado is in the offing.
At present, most tornado detection relies on either groups of roving “tornado spotters” or weather radar.
Schmitter reckons that detecting the electromagnetic waves should offer advantages over both methods. Low-frequency radiation can penetrate further through cloud than microwaves, giving a more accurate picture of the heart of storm. The new approach should also be quicker as an electromagnetic signal could be picked up instantly, whereas it takes a few minutes to refresh each new radar scan.
The method would also offer advantages over tornado hunters who rely on eyes alone to gauge developing storms and cannot always get close enough to the storm to get a clear picture of the area of rotation.
The research does indeed appear to be promising, in light of the anecdotal evidence from historical testimony. But, moreover, it seems to be in line with prior theorerical papers from several prominent meteorologists and physicists.
Some historical testimony (from the likes of R.S. Hall, above) has likened the internals of tornadoes to fluorescent lights. But is the analogy apt? Tentatively, yes, it does appear to offer a path of inquiry. In fact, just such an inquiry was, intentionally or not, performed by Bernard Vonnegut in experiments with high voltage discharges and vortexes.
Without a vortex, a stable spark could not be maintained if the electrodes were more than 37 mm apart. A spark between electrodes having the separation is shown in fig. 3. When the blower was turned on and a vortex was created, we observed that the discharge between the electrodes became more steady, that its diameter increased, and that it appeared to assume the characteristic of a glow rather than a spark discharge. Fig. 4 shows the appearance of the discharge when the vortex is present. When the vortex was turned on, we observed that the potential difference across the discharge dropped from 6.0 kv to 4.3 kv and that the current increased from 17.5 to 19 milliamperes. It was also observed that, without the vortex, the discharge produced considerable radio-frequency noise in the broadcast band but that, when the vortex was turned on, this noise disappeared.
It was further observed that with the vortex it was possible to obtain a stable discharge even when the electrodes were as much as 68 mm apart. Such a discharge is shown in fig. 5. The potential difference in this case is 7.3 kv, and the current is 14.5 milliamperes.
In essence, it was found that without a vortex a spark discharge could not be initiated if the electrodes were too far apart. Moving the electrodes closer together would reduce the spark gap and increase the electric field potential between the electrodes, allowing a spark to form. However, when a vortex was created with a fan, a lower-intensity discharge (a glow discharge) was able to form between the electrodes over longer distances. The implication is that rotation due to wind shear may create an environment conducive to a glow discharge (tentatively, a tornado), where a spark discharge (lightning) is not possible due to insufficient electric field potential between the cloud and the Earth.
This would appear to be not out-of-line with the reports of electrical glows within the funnels of tornadoes, in the few instances where the innards have been accidentally observed.
It is possible that the electrical forces involved may also give the tornado some portion of its destructive power on the ground. Where charges are out of balance, the electrical force dominates over the force of gravity!
Have you ever wondered why that little piece of plastic wrap clings to your hand (static [electric] cling), despite violently shaking it and despite the entire gravitational potential of the Earth resting below your feet pulling downward it? Yep, that’s how much stronger the raw electric force is with respect to gravity…
The notion of electrical forces playing a significant role in tornadoes is not especially new, just not well-known. In fact, several notables have contributed anecdotally to the theory. Their collected works may be greater on the whole than any one single contribution.
In addition to the paper above on stabilization of a high-voltage discharge, Bernard Vonnegut also penned a paper on the Electrical Theory of Tornadoes (abstract below):
Modern theory and observations appear to support the very old and almost forgotten idea that tornadoes are a manifestation of thunderstorm electricity. It is suggested that there is sufficient electrical energy in an intense thunderstorm to power a tornado and that the electrification could cause extraordinarily intense winds by electrically heating air or by accelerating charged air in an electric field.
The theory of “electrically heating air” has been largely discarded as a formative mechanism. Accelerating charged particles in the air, and thus the air itself through collisions of those particles with neutral particles in the air, has not been as widely studied. However, a few notable papers have been penned on the subject.
C. Souzou treated the topic with a paper written back in 1984, specifically noting that rather than using the typical argument of “electrical heating,” his concern was in applying the Lorentz force.
… The idealized solution is, in effect, the superposition of two existing solutions both of which are associated with up-draught velocities and lends qualitative support to theories that associate tornado vortices with electrical activity, though here the agency generating the velocity field is the Lorentz force and not, the usually assumed, electric heating.
Thomas Dehel, et al, penned a paper entitled “Electric Field and Lorentz Force Contribution to Atmospheric Vortex Phenomena” that also treats tornado initiation and sustenance specifically utilizing the Lorentz force.
The physics that initiate and sustain tornadoes and dust devils is still under investigation. Forces that operate throughout a wide range of scales and could contribute to atmospheric vortex phenomena are the Lorentz force and the force of electric fields. The Lorentz force results in a circular motion of charged particles in a magnetic field. An electric field will pull or repel a charged particle in the direction of the field. This paper will demonstrate that the Lorentz force and the force of electric fields, acting on charged particles that exist in atmospheric vortex phenomena, plausibly contribute to the set of physics that will explain tornadoes and other atmospheric vortex phenomena.
However, the treatment of tornadoes as electrical phenomena goe back at least as far as ’59-’60 in the form of a paper by E.R. Rathbun entitled “An Electromagnetic Basis for the Initiation of a Tornado.”
A new suggestion, which is believed worthy of further investigation, is offered here. It is advocated that not only is there a significant factor to be found in electrical activity but that the Earth’s magnetic field is also important. These parameters are believed to be especially significant during the initial phases of the storm.
The exact conditions that are relevant require further investigation.
Bothun, Patton and Sessions provide their own contribution in a paper entitled “An Electric Force Facilitator in Descending Vortex Tornadogenesis”.
We present a novel explanation of the physical processes behind one type of cloud and ground-level tornadogenesis within a supercell. We point out that the charge separation naturally found in these large thunderstorms can potentially serve to contract the preexisting angular momentum through the additional process of the electric force. On the basis of this, we present a plausible geometry that explains why many tornado vortices begin at storm midlevel and build downward into ground-level tornadoes. A simple model based on this geometry is used to demonstrate the strength of the electric force compared to the required centripetal acceleration to maintain cloud midlevel tornado vortices measurable as tornado vortex signatures (TVSs). Furthermore, a model based on this geometry is used to get a time estimate for tornado vortex formation. From this we are able to identify a plausible value for the threshold charge density that would lead to tornadogenesis and tornado maintenance on the timescale of a few minutes. We show that the proposed geometry can explain the observations that ground-level tornadoes thrive in regions with high shear and large convective available potential energy (CAPE) and are able to make some predictions of specific measurable quantities.
Other pertinent papers include but are by no means limited to “Electric Currents Accompanying Tornado Activity” by Marx Brook and “On the Geo-Electromagnetic Aspects of Tornado Initiation” by F.A. Berson and H. Power.
All told, it seems that this “all things old are new again” approach may inevitably pay off if all the pieces of the puzzle can be brought together effectively and the thoery can be efficiently and rigorously tested in the lab and in real life.
If and when we understand the mechanics of tornado initiation and sustenance, it might even be possible to devise a method of tornado control. Though it sounds a bit like scienec fiction, with our present level of understanding, science soldiers on. Who knows what the future might hold? Exciting times lie ahead.