6.4 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Ball lightning | 1/8 | https://en.wikipedia.org/wiki/Ball_lightning | reference | science, encyclopedia | 2026-05-05T11:04:47.852283+00:00 | kb-cron |
Ball lightning is a rare and unexplained phenomenon described as luminescent spherical objects that vary from pea-sized to several meters in diameter. Though usually associated with thunderstorms, the observed phenomenon is reported to last considerably longer than the split-second flash of a lightning bolt and is distinct from St. Elmo's fire and will-o'-the-wisp. Some 20th-century reports describe balls that eventually explode and leave behind an odor of sulfur. Descriptions of ball lightning appear in a variety of accounts over the centuries and have received attention from scientists. An optical spectrum of what appears to have been a ball lightning event was published in January 2014 and included a video at high frame rate. Nevertheless, scientific data on ball lightning remain scarce. Although laboratory experiments have produced effects that are visually similar to reports of ball lightning, how these relate to the phenomenon remains unclear.
== Characteristics == Descriptions of ball lightning vary widely. It has been described as moving up and down, sideways or in unpredictable trajectories, hovering and moving with or against the wind; attracted to, unaffected by, or repelled from buildings, people, cars and other objects. Some accounts describe it as moving through solid masses of wood or metal without effect, while others describe it as destructive and melting or burning those substances. Its appearance has also been linked to power lines, altitudes of 300 m (1,000 feet) and higher, and during thunderstorms and calm weather. Ball lightning has been described as transparent, translucent, multicolored, evenly lit, radiating flames, filaments or sparks, with shapes that vary between spheres, ovals, tear-drops, rods, or disks. Although they are separate and distinct phenomena, ball lightning is often erroneously identified as St. Elmo's fire. The balls have been reported to disperse in many different ways, such as suddenly vanishing, gradually dissipating, being absorbed into an object, "popping", exploding loudly, or even exploding with force, which is sometimes reported as damaging. Accounts also vary on their alleged danger to humans, from lethal to harmless. A review of the available literature published in 1972 identified the properties of a "typical" ball lightning, whilst cautioning against over-reliance on eye-witness accounts:
They frequently appear almost simultaneously with cloud-to-ground lightning discharge They are generally spherical or pear-shaped with fuzzy edges Their diameters range from 1–100 cm (0.4–40 inches), most commonly 10–20 cm (4–8 inches) Their brightness corresponds to roughly that of a domestic lamp, so they can be seen clearly in daylight A wide range of colors has been observed, with red, orange, and yellow being the most common The lifetime of each event is from one second to over a minute with the brightness remaining fairly constant during that time They tend to move at a few meters per second, most often in a horizontal direction, but may also move vertically, remain stationary, or wander erratically Many are described as having rotational motion It is rare that observers report the sensation of heat, although in some cases the disappearance of the ball is accompanied by the liberation of heat Some display an affinity for metal objects and may move along conductors such as wires, metal fences, or railroad tracks Some appear within buildings passing through closed doors and windows Some have appeared within metal aircraft and have entered and left without causing damage The disappearance of a ball is generally rapid and may be either silent or explosive Odors resembling ozone, burning sulphur, or nitrogen oxides are often reported
== Historical accounts == Ball lightning is a possible source of legends that describe luminous balls, such as the mythological Anchimayen from Argentinean and Chilean Mapuche culture. According to a statistical investigation carried out in 1960, of 1,962 Oak Ridge National Laboratory monthly role personnel, and of all 15,923 Union Carbide Nuclear Company personnel in Oak Ridge, found 5.6% and 3.1% respectively reported seeing ball lightning. A Scientific American article summarized the study as having found that ball lightning had been seen by 5% of the population of the Earth. Another study analyzed reports of more than 2,000 cases.
=== Gervase of Canterbury === The chronicle of Gervase of Canterbury, an English monk, contains what is possibly the earliest known reference to ball lightning, dated 7 June 1195. He states, "A marvellous sign descended near London", consisting of a dense and dark cloud, emitting a white substance that grew into a spherical shape under the cloud, from which a fiery globe fell towards the river. Physicist Emeritus Professor Brian Tanner and historian Giles Gasper of Durham University identified the chronicle entry as probably describing ball lightning, and noted its similarity to other accounts:
Gervase's description of a white substance coming out of the dark cloud, falling as a spinning fiery sphere and then having some horizontal motion is very similar to historic and contemporary descriptions of ball lightning ... It is fascinating to see how closely Gervase's 12th century description matches modern reports of ball lightning.
=== Great Thunderstorm of Widecombe-in-the-Moor ===
One early account reports on the Great Thunderstorm at a church in Widecombe-in-the-Moor, Devon, in England, on 21 October 1638. Four people died and approximately 60 suffered injuries during a severe storm. Witnesses described an 8-foot (2.4 m) ball of fire striking and entering the church, nearly destroying it. Large stones from the church walls were hurled onto the ground and through large wooden beams. The ball of fire allegedly smashed the pews and many windows, and filled the church with a foul sulfurous odor and dark, thick smoke. The ball of fire reportedly divided into two segments, one exiting through a window by smashing it open, the other disappearing somewhere inside the church. Because of the fire and sulphur smell, contemporaries explained the ball of fire as "the devil" or as the "flames of hell". Later, some blamed the entire incident on two people who had been playing cards in the pews during the sermon, thereby incurring God's wrath.