Lightning, Plasma and Balls of Fire
April 1967 Radio-Electronics

April 1967 Radio-Electronics

April 1967 Radio-Electronics Cover - RF Cafe[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Electronics, published 1930-1988. All copyrights hereby acknowledged.

"A typical discharge of lightning releases nearly 100 million volts along its path - through which as much as 250,000 amps of current flows. Temperatures reach 30,000°C, roughly five times the surface temperature of the sun. The stroke lasts only a few milliseconds, so the average power is low-typically from 10 to 100 watts." Let's see... 100 MV x 250 kA = 25,000 gigawatts (Doc Brown's DeLorean only needed 1.21 GW). Over 1 ms that's an energy of 25 gigajoules. I'm not sure where the 10 to 100 watts of "average" power in the article comes from. The National Weather Service says, "A typical lightning flash is about 300 million volts and about 30,000 amps." That's 9,000 gigawatts, enough for 7,438 time travel trips. ...but I digress. The April 1967 issue of Radio−Electronics magazine had a cover announcement of "Lightning and UFO's." This is the article to which it refers.

Lightning, Plasma and Balls of Fire

Common form of lightning is now believed to energize the type of "ball lightning" - RF Cafe

The common form of lightning is now believed to energize the type of "ball lightning" that may explain reports of several kinds of visual phenomena, including many UFO's.

A review of natural electrical discharges in the skies.

By Allen B Smith

To most of us, lightning is something that comes naturally with summer thunderstorms, and we usually don't worry about it. It's only when this powerful atmospheric electricity oversteps the bounds of good manners that it becomes a matter for attention. It's difficult to overlook the explosive shattering of a large tree near your house, or a lightning-caused forest fire which ravages thousands of acres of valuable timber. Worst of all is the stroke that snuffs out the lives of a family huddled away from a driving rainstorm under the branches of an old oak.

Electronics technicians - like many other people - have long been aware of the lethal power of lightning. We know that human carelessness leads to serious injury and property damage caused by lightning. In the normal course of our work, we've established safety procedures: Ground that antenna mast; use a lightning arrester on that lead-in. We have developed a healthy respect for the power contained in a storm cloud - and with good reason.

A typical discharge of lightning releases nearly 100 million volts along its path - through which as much as 250,000 amps of current flows. Temperatures reach 30,000°C, roughly five times the surface temperature of the sun. The stroke lasts only a few milliseconds, so the average power is low-typically from 10 to 100 watts. But its energy, as we all know, has astonishing effects. We also know that this form of electricity is the least predictable. About all we can do is wait for it to strike.

Early Discoveries

The apparently random and capricious behavior of lightning accounts in part for the belief in fire gods and other mystical beings among men of earlier civilization. Not surprisingly, some primitive cultures were strongly centered around the power of lightning, usually in the keeping of their strongest god. Even the Greeks and Romans had rather special views about atmospheric electricity.

In Rome, for example, there was a body of especially learned men known as the College of Augurs whose sale purpose was to predict the will of the gods. To obtain this extremely important information, the augurs observed the random action of birds, meteorites and comets, and lightning. Lightning, it was believed, was controlled by Jupiter, the most powerful of Roman deities. The direction from which lightning struck, the quarter of the sky in which it was seen, its intensity and physical character - all these had significance in determining the will of Jupiter.

Today, we have a far more scientific understanding of the causes and effects of lightning, but the new confidence with which we regard it is only as old as the experiments and observations of Benjamin Franklin. As one of a small number of educated men using the scientific method in studying natural phenomena, Franklin described, in 1750, an apparatus to determine whether the electrical charge held within a cloud could be tapped off and carried harmlessly to the ground. The device was constructed first in France, but Franklin proved to his own satisfaction - during the famous kite experiment - that the charge could, indeed, be grounded. He later described the construction and installation of lightning rods and grounding systems based on these observations.

Scientific studies of lightning in its various forms have been pursued by a surprisingly large body of scientists. In all parts of the world, visual, photographic and physical observations have resulted in a massive written record. Practically every aspect of the phenomenon is quite neatly cataloged.

Fire Balls

There is one significant exception, however. Like a thin wisp of smoke in a clear sky, descriptions of a maverick variation generally called "ball lightning" are found throughout the entire recorded history of lightning sightings. Refusing to follow the well-known behavior patterns of its common relative, ball lightning may roll along the ground, pop through an open window or down a chimney, ricochet off the walls of a house, sit on a fence, hum, buzz, hover, fade away or explode. Somehow, the first impression one gets in reading about the stuff is that everyone who claims to have seen it has a different story to tell.

Following an extensive study of ball-lightning observations, scientist Donald J. Ritchie concludes that there probably are two basic types. The first is a diffuse red ball which fades slowly without doing any apparent damage. The second is bright, bluish-white and decays rapidly with a loud explosion, charring and blasting nearby objects. The balls apparently range in size from an inch or so to as much as 30 or 40 feet in diameter; the average seems to be about 1 foot. Their lifespan is anywhere from a few seconds to 3 minutes on the average, yet Ritchie notes that one very large ball was seen hanging below the base of a storm cloud for 15 minutes.

Graphical representation of the Uman/Helstrom theory of ball lightning - RF Cafe

Fig. 1 - Graphical representation of the Uman/Helstrom theory of ball lightning shows the limits of current density and current for balls of varying diameters.

Probably the most unusual aspect of these electrical enigmas is that they move as if they had no appreciable weight, sometimes very quickly, sometimes just barely creeping along, changing direction rapidly and at random. In one incident, reported by eyewitness J. Durward (a one-time director of the British Meteorological Service), a ball of fire entered the cockpit of an airliner flying through a heavy thunderstorm. It passed in through an open window vent, singed the eyebrows of the captain, burned holes in his safety harness and flight case, bounced through the passenger cabin into the rear of the craft, where it burst in a loud explosion.

In spite of literally hundreds of reported sightings in recent years, photographs of ball lightning are extremely rare. Those which do exist have been judged by some investigators as frauds and by a few as due to other natural phenomena. Others, of course, believe that the pictures represent actual images of ball lightning.

UFO's and Lightning

At this point you already may have formed the idea that many of the characteristics of so-called ball lightning also may be ascribed to at least one kind of UFO's (unidentified flying objects). In one famous case, investigated by John Fuller and reported in his book Incident at Exeter, 60 people observed some kind of bright and highly mobile object. It darted through the skies of Exeter, N. H., before disappearing. There seems to be no doubt that observers actually saw something strange and captivating that night in September 1965. Fuller's conclusion was that the shimmering glow which visited Exeter was a spaceship from a planet in another solar system. Even though such a visit is possible, Fuller's explanation doesn't seem too convincing. Exeter's spaceship sounds like many descriptions of ball lightning.

Noted astronomer Harlow Shapley (fifth director of the Harvard Observatory) believes that perhaps as many as 100,000 planets capable of supporting some form of intelligent life may exist within our own galaxy, the Milky Way. Harrison Brown of Cal Tech says a thousand or so. If either is correct, then at least one of these higher forms of life may wish to visit what must seem to them to be our remote and insignificant solar system. But, all "evidence" of such visits seems poorly observed, badly reported and devoid of scientific basis or credibility. Visual evidence, as we all know, can be extremely misleading.

Until recently the subject of ball lightning was a muddled morass of unsupported observation. Like reports of flying saucers and other UFO's, it was regarded by most of the scientific community as part of an interesting folklore, good for spirited conjecture and little else. In May 1966, however, two scientists at the Westinghouse Research Labs published a report that has added strong evidence that ball lightning actually does exist. Its physical and electrical characteristics are described in careful detail.

Drs. M. A. Uman and C. W. Helstrom, with the assistance of a high-speed computer, have constructed a mathematical model that predicts the properties of ball lightning in terms of known physical forces. The Uman-Helstrom model describes the ball in terms of current density, temperature and diameter. The descriptions agree in surprising detail with recorded observations of ball lightning.

As Fig. 1 shows, central temperatures in a lightning ball may range from 3,500°C to 6,000°C, 58% to 100% of those found at the sun's surface. Current flowing within the ball itself varies from a few tenths to several hundreds of amps. The ball size is predicted as a function of temperature and of the current density that exists in the air between the storm cloud and the ground.

The theory also predicts that a ball having an 8-inch diameter and a 5,000°C central temperature would be as bright as a 1,000-watt light bulb.

Electric Gas

Weakly ionized gas has a high density of neutral molecules - RF Cafe

Fig. 2 - Weakly ionized gas has a high density of neutral molecules. Increasing ionization decreases number of neutral molecules. Completely ionized gas has no neutral molecules.

Uman and Helstrom based their work on a phenomenon that's been known only a short time to physicists - the effect known as plasma. (Not to be confused with plasma - the fluid part of blood.) When a gas becomes ionized to the point that it contains a nearly equal quantity of electrons and positive ions, it's called plasma. How does it differ from ordinary gas? For one thing, it's a good conductor of electricity. Also, it's affected by magnetic fields.

We know that gas in its normal state is an electric insulator, and that application of intense electrostatic or electromagnetic fields will release free electrons and ions. Under these conditions, the gas becomes conductive and remains so as long as the gas-discharge conditions are met. The ionized gas consists of electrons, positive ions, and neutral molecules. The electrons and ions in a given volume of ionized gas tend to balance in number, because any excess, either of ions or electrons, creates an intense electrostatic field that tends immediately to restore the condition of particle balance.

Complete equilibrium for the ionized gas depends additionally on the molecular density of the gas, its temperature and the degree of ionization. This total equilibrium normally exists for all degrees of ionization. In weakly ionized gases, the ratio of positive ions and free electrons to neutral molecules is very low. In strongly ionized gases, however, the ratio is high. And, in a completely ionized gas of specific volume, the density of neutral molecules is zero. The resulting incandescent gas cloud is called a plasma.

To put it another way: The ionized gas which generates the light in a fluorescent tube is weakly ionized; the controlled-fusion reaction of the sun with its extraordinarily powerful magnetic field is a hydrogen plasma.

Because large regions of the universe and many specific stellar and nebular bodies now are assumed to be plasmas, the study of their characteristics is of basic interest to astrophysicists and cosmologists. Nuclear explosions produce matter that is almost completely ionized, as do the superconducting magnets used by physicists working to control the fusion reaction of heavy hydrogen. The entire concept of radio astronomy is based on the intense electromagnetic radiation of stellar bodies, particularly the class of radio stars known as quasars - another form of galactic plasma.

Physicists often remark that plasmas constitute the fourth state of matter, being neither liquid, gas nor solid. No matter how one views them, certainly their importance in achieving a better understanding of basic physical forces is hard to exaggerate. Plasma research undoubtedly will lead to controlled-fusion power, to pulsed-plasma engines of low thrust and extremely high (near the speed of light) velocities for interplanetary and interstellar space-craft, and to a more complete understanding of how the entire universe was formed and developed.

Lightning and Plasma

How does the Uman-Helstrom theory of ball lightning relate to the conditions of plasma generation? The electrostatic charge necessary for ionizing a small volume of air lies between a highly charged cloud and the ground. The heating requirement is met by a lightning stroke - usually far in excess of the temperature needed to ionize the air completely. Still, there must be a missing ingredient. Otherwise, every lightning stroke would create a plasma, and ball lightning would be bouncing from wall to wall during every thunderstorm.

According to research conducted at the Illinois Institute of Technology in which ball lightning was artificially generated, the volume of air from which the plasma is formed must differ in some way from the air that surrounds it. This difference may result from just the right distribution of dust particles, from random concentrations of foreign gases (hydrogen sulfide, methane, ammonia. etc.) or from almost any form of contamination that happens to be directly in the path of a lightning stroke and in the presence of a strong magnetic field. The relative rarity of ball lightning attests to the odds against all of these circumstances occurring simultaneously and within the limits shown in the graph. But when they do occur - Fireworks!

Once the plasma has been formed, the fireball is free to move in response to the constantly changing magnetic field surrounding it. When the cloud-to-ground currents are symmetrical around the ball and flow symmetrically through it, the net force is zero, and the ball hangs stationary in space. It has, after all, the same weight as the surrounding air. Any change in the distribution of the magnetic field will cause the ball to move. Further, any change in the symmetrical shape of the ball also will impart motion, due to a resulting distortion of the field. In particular, an elongated or cigar-shaped ball is very unstable and moves at high speeds.

When the magnetic field supporting the plasma collapses slowly, the degree of ionization is reduced and the ball, like an old soldier, just fades away. If the magnetic field collapses abruptly, or if the ball moves into an area shielded from the field, all the latent energy held in the ball is released at once. The result is an explosion, the severity of which depends on the size of the ball, the temperature inside it, the molecular current density and the strength of the field at the time of collapse.

Well-documented accounts of this phenomenon have described massive damage to buildings, multiple deaths from blast and burns, and other examples of high-energy release. One of the most serious of these occurred during a tornado that struck a small village in Dartmoor, England, on a Sunday in October 1638. After being assaulted by high winds and lightning, a church (in which services had just begun) was bombarded by a fireball which moved through the main hall, severely burned several parishioners, then exploded. More than 60 persons were killed in the resulting blast and collapse of the damaged building.

It's apparent that ball lightning, especially now that its formation and existence have been verified by mathematical computation and by the IIT experiments, may hold the answer to a variety of previously unexplained occurrences. Foremost among these, of course, are the reports of UFO's that glow in night skies, move erratically at high speed with a buzzing sound, then disappear - either silently or with a loud report.

This possible explanation for several types of UFO's is strengthened when we learn that a plasma may be formed in the vicinity of high-voltage power lines, even in particularly dry weather. What's more, operators of NASA's rocket-tracking radars, who follow the paths of satellite-launch vehicles, know that the plasma trail formed by a massive rocket is easier to obtain an echo from than the craft itself.

Since the Air Force now has authorized a serious study of UFO's - interestingly enough, under the direction of the research and development branch rather than the intelligence agency as before - this new interest in plasmas and ball lightning surely will not go unnoticed. At this time, of course, we have no way of knowing whether further investigation will show that ball lightning and other plasmas account for most UFO reports.

If it does - and this seems likely - I'll be among those who will feel a little let down. I've been interested in some of the serious efforts in books and magazine articles that attempt to show that earth has been visited by visitors from outer space. Theories have been proposed describing members of some higher life form, whose home probably lies far beyond the comfortable confines of our own solar system. Frankly, I like the idea that the extraordinary interstellar and intergalactic distances can somehow be spanned despite the contradictions of our brief lifespans and the apparent limitation of the speed of light (186,000 miles per second) as our greatest attainable spaceship velocity.

I'd like to believe the theories. But the evidence - scientific evidence - so far isn't convincing. Right now, I'll place my bets on the balls of fire.



Posted March 25, 2024