Tikalon Blog by Dev Gualtieri

Ball Lightning

March 28, 2022

There's always interest in things cataloged as being "the greatest of all time," an example being just retired, then not-so-retired, football quarterback, Tom Brady (b. 1977), who earned the GOAT moniker for his exemplary performance. A recent review of data from the Geostationary Lightning Mapper on NOAA's GOES-16 satellite by the World Meteorological Organization has discovered the greatest of all time lightning flash that occurred on April 29, 2020 (see image). This lightning flash covered a horizontal distance of 477 miles (768 kilometers) that extended through three US states (Mississippi, Louisiana, and Texas).[1-2]

Lightning as seen from the Geostationary Lightning Mapper on NOAA's GOES-16 satellite from April 29, 2020. The World Meteorological Organization found that one lightning flash within this thunderstorm complex extended a horizontal distance of 477 miles (768 kilometers), making it the longest lightning flash on record. The previous record was a 440.6 mile (709 km) lightning flash recorded in Brazil in 2018.[1] Lightning rarely extends over 10 miles. (NOAA image. Click for larger image.)

A typical lightning flash is about 300 million volts and about 30,000 amperes, which calculates to 9 billion kilowatts. Since a typical flash is about a tenth of a second, this calculates to about 250 kilowatt-hours of electricity and 900 million joules of energy. Such a force of nature deserves attention, and I've written some previous articles on lightning (Climate Change and Lightning, November 26, 2014 and Lightning Striking Again, September 17, 2015).

The Internet has enabled many crowd-sourced projects, one of which is a very useful lightning monitoring network facilitated by Blitzortung.org. A nice graphical view of the data can be seen at lightningmaps.org. Some regions have a higher probability of lightning strikes, as illustrated in the following figure.

Global probability of lightning strikes (NSSTC Lightning Team)

Lightning strike probability, as shown on a map of the world, created from space-based optical sensing. The units are flashes per square kilometer per year. It's apparent that the warmer equatorial regions have higher probability, and it's been conjectured that global warming will increase the worldwide probability of lightning. It's estimated that a one degree Celsius increase in temperature leads to an increase in the frequency of lightning strikes of 12%.[3] (NSSTC Lightning Team image, via NASA.)[4]

Lightning was a major hazard centuries ago, when most of the population lived on farms in which their barn and dwellings were tall objects in the middle of flat fields. As I wrote in an earlier article (Our Technologist Forefathers, July 3, 2012), Benjamin Franklin (1706-1790), the inventor of the Franklin stove and bifocals, also invented the lightning rod. In his experiments with electricity, Franklin noticed that pointed conductors discharged at a greater distance than blunt conductors, so he thought that the converse property was also true, that these would be better at attracting charge. Franklin tested lightning rods designed according to this principle at his own home, and he later had them installed at the Pennsylvania State House, now named Independence Hall.

The kite experiment is the most popular image of Franklin.

This engraving is from the 1881 textbook, "Natural Philosophy for Common and High Schools," by Le Roy C. Cooley (fig. 82 on page 159).

In Franklin's experiment, the hemp kite string, wet with rainwater, conducted electricity from the upper atmosphere to a door key. The door key was insulated from the string holder by a silk cord.

The popular image of lightning striking the kite is wrong. The kite just allowed charge from the upper atmosphere to be conducted to ground level.

((Wikimedia Commons image). Click for larger image.)

Everyone is familiar with the appearance of ordinary lightning bolts, but there's another type of lightning known as ball lightning that exists as a longer lasting compact sphere. There is no consensus on the principle behind ball lightning creation or its properties. Scientists are creative people, and the Wikipedia page on ball lightning lists quite a few explanations, some that I think are the more plausible explanations (and one representative implausible explanation) are listed here:

• Vacuum Hypothesis. This hypothesis is interesting, since it demonstrates that an explanation of ball lightning was considered as far back as 1899. The master electrician of that time, Nikola Tesla (1856-1943), a man who created his own lightning bolts, conjectured that ball lightning consisted of highly rarefied hot gas. I'm reminded of the similar phenomenon, sonoluminescence.

• Vaporized Silicon Hypothesis This hypothesis suggests that ball lightning is actually silicon, vaporized by a lightning strike to soil and turned into an aerosol, that burns by oxidation. Experiments have created such luminous balls with a lifetime of a few seconds, and a captured emission spectrum of natural ball lightning lends credence to this idea.

• Microwave Cavity Hypothesis. This hypothesis was first proposed by Nobel Physics Laureate, Pyotr Kapitsa (1894-1984). In this hypothesis, the ball is a resonant microwave cavity surrounded by plasma. The cavity is pumped by an atmospheric maser associated with the thunderstorm.

• Soliton Hypothesis. In this ball lightning model, a plasma ball is host for spherically symmetric nonlinear oscillations of charged particles.

• Transcranial Magnetic Stimulation. I mention this theory only because the usual explanation for unexplained phenomena is "mass hallucination." In this case, a little science is added in stating that magnetic fields can induce visual hallucinations resembling ball lightning. There is, however, much evidence that ball lighting is a physical effect, and not an hallucination.

• Rydberg Matter Concept. This idea, proposed in 2003 by my former research director, Jack Gilman (1925-2009), is that ball lightning consists of highly excited Rydberg atoms with large polarizabilities that bind them together through London dispersion forces.[5] I wrote about Jack in an earlier article (Strength of Materials, May 11, 2020).

• Collective Oscillations of Free Electrons. According to this hypothesis, the balls undergo radial oscillations that suck in charged particles from the air around them to act as fuel.

While scientific data on ball lightning is still scarce, there's one observation that's quite complete. An account of a mid-1960s ball lightning incursion into a C-133A "Cargomaster" aircraft was recently published by Don Smith, a retired member of the United States Air Force.[6] Smith was the navigator aboard the C-133A cargo aircraft that was flying from California to Hawaii at night at an altitude of 18,000 feet. There were no storms in the vicinity, but the nose radome, visible from inside the cockpit, developed two horns of Saint Elmo's fire, each about a foot long, glowing blue.[6]

Suddenly, a glowing ball about the size of a volleyball appeared just inside the windshield. (see figure). The ball didn't make contact with anything, and it didn't make any noticeable sound. The ball floated slowly downward between the pilots and the other cockpit crew members, and it came within a foot of Smith, at his waist, about three feet above the floor. It then proceeded to drift throughout the aircraft. A careful check of the aircraft while in flight, and later, while on the ground, revealed no damage. The ball lightning appeared about halfway between Travis AFB, California, and Hickam AFB, Hawaii.[6]

Ball lightning in an aircraft, reconstruction by Don Smith.

Reconstruction of ball lightning in an aircraft. (Fig. 2 of ref. 6, licensed under a Creative Commons license.[6] Click for larger image.)

Gervase of Canterbury (c.1141-c.1210), an English monk, wrote a chronicle that contains the earliest known reference to ball lightning.[7-10] As he wrote, a dense, dark cloud appeared above London on June, 7, 1195, and it emitted a white substance. This substance grew into a spherical shape beneath the cloud, and a fiery globe fell from it towards the river.[7] Similarly to the aircraft sighting above in which no storms were present, the London event happened on an otherwise sunny day.[10] This is the earliest known description of ball lightning in England.[7]

The discovery of this earliest published account of ball lightning was made by emeritus physics professor, Brian Tanner, and professor of history, Giles Gasper of Durham University (Durham, UK).[7] Gervase's Chronicle and his other works exist as three extant manuscripts, one at the British Library, and two at the University of Cambridge.[7-8] The Gervase account predates the previously known early description of ball lightning recorded in England by about 450 years.[8-9] That was in a description of a great thunderstorm in Widecombe, Devon, on October 21, 1638.[9-10] An earlier 1556 claim wasn't published until 1712, by the historian, Thomas Atkyns.[10]

Engraving depicting ball lightning, and a portion of the Chronicle of Gervase of Canterbury which describes a ball lightning event.

Left, a 19th century engraving depicting ball lightning by Lantzy via Wikimedia Commons. Right, a Durham University photograph of a portion of the Chronicle of Gervase of Canterbury (c.1141-c.1210) where the medieval monk describes his observation of ball lightning, courtesy of The Master and Fellows of Trinity college, Cambridge, MS R.4.11, p.324. (Click for larger image.)

Gervase's Latin text was edited by Bishop William Stubbs (1825-1901) in 1879, and there is no English translation.[9] The ball lightning description is an entry between an announcement of a new abbot of St. Albans and the removal of the abbot of Thorney.[10] Although the primary purpose of the chronicle was to document activities of Christ Church Cathedral Priory in Canterbury and actions by the king and his nobles, it also contained natural phenomena, such as celestial events, floods, famine, and earthquakes.[9] Says Tanner,

"We should not dismiss medieval descriptions of the natural world as being mired in superstition and therefore of no value. This event was evidently sufficiently spectacular for it to merit special mention in the chronicle. Ball lightning was not understood then and it is still not understood now."[7]

This sentiment is affirmed by Susan Powell of BBC Weather, who says

"Modern technology allows us to observe our weather in more detail than ever before and understand with greater depth. Ball lightning however remains elusive and it's the subject of many theories. It's interesting to think that in this respect, despite our advances, we stand as mystified as observers in the 12th century."[7]

Ball Lightning

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