Hubbry Logo
Crown flashCrown flashMain
Open search
Crown flash
Community hub
Crown flash
logo
7 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Crown flash
Crown flash
Crown flash
View on Wikipedia
from Wikipedia

Crown flash is a rarely observed meteorological phenomenon caused by the effect of atmospheric electrical fluctuations on the alignment of ice crystals. It has been described as "the brightening of a thunderhead crown followed by the appearance of aurora-like streamers emanating into the clear atmosphere".[1] The current hypothesis for why the phenomenon occurs is that sunlight is reflecting off, or refracting through, tiny ice crystals above the crown of a cumulonimbus cloud. These ice crystals are aligned by the strong electric field effects around the cloud,[2] so the effect may appear as a tall (sometimes curved) streamer, pillar of light, or resemble a massive flash of a searchlight/flashlight beam. When the electric field is disturbed by electrical charging or discharging (typically, from lightning) within the cloud, the ice crystals are re-oriented causing the light pattern to shift in a characteristic manner, at times very rapidly and appearing to 'dance' in a strikingly mechanical fashion.[3] The effect may also sometimes be known as a "leaping sundog" or "jumping sundog". As with sundogs, observation of the effect is dependent upon the observer's position – it is not a self-generated light such as seen in a lightning strike or aurora, but rather a changing reflection or refraction of the sunlight. Unlike sundogs, however (which are also caused by refraction of sunlight through ice crystals), these features move and realign within seconds, forming beams and loops of light, and the effect appears localised directly above the cloud rather than at some distance to the side(s) of the sun.

The first scientific description of the crown flash phenomenon appears to be in the journal Monthly Weather Review in 1885,[4] according to the Guinness Book of Records.[5] Also mentioned in Nature in 1971[6] and in a letter to Nature slightly earlier in the same year,[7] this phenomenon is regarded as uncommon and not well documented. Starting with an initial video upload in 2009 dozens of YouTube videos have since been emerging that appear to document this phenomenon.[8]

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Crown flash

View on Grokipedia
from Grokipedia
Crown flash is a rare optical meteorological observed as intermittent, rapidly oscillating beams or patches of emanating from the upper regions of cumulonimbus clouds, particularly during thunderstorms, resembling a luminous crown or jumping sundog. It manifests as bright, feather-like luminescence that sweeps downward and upward in jerky motions over seconds, often triggered by discharges within the cloud. The phenomenon arises from the interaction of with oriented ice crystals suspended above the cloud top, typically in the form of thin plates or elongated at altitudes around 10-12 km. These crystals become temporarily aligned by the intense, fluctuating produced by charge separations in the thundercloud, which can reach strengths of 10-100 kV/m; this alignment enhances forward scattering and reflection of , creating the visible flashes without involving actual electrical discharge through the air. When the changes—often due to intracloud —the crystals reorient, causing the light patterns to shift and "jump," a sometimes exhibiting a "memory effect" where prior alignments influence subsequent ones in certain temperature ranges. First scientifically documented in 1885 in the Monthly Weather Review by an observer in the United States, crown flash was initially mistaken for unusual lightning but later explained through atmospheric optics in the mid-20th century. Pioneering research by Bernard Vonnegut and others in the 1960s-1970s proposed the ice crystal-electric field mechanism, supported by observations linking it to active storm conditions and confirmed by modern video analyses showing no thermal or electrical signatures of true lightning. Though sightings remain infrequent—requiring clear sunlight, specific crystal habits, and strong fields—advances in amateur videography have documented dozens of events since the 2010s, aiding further study of thunderstorm electrodynamics.

Description

Definition

A crown flash is a rare characterized by a sudden brightening at the crown of a thunderhead—the upper portion of a . This effect manifests above the cloud top and lasts several seconds, often repeating at intervals of 30 to 60 seconds. Crown flashes occur exclusively above active cumulonimbus clouds during daylight hours, when sunlight is available to illuminate thin cirriform layers or the cloud's upper structure through reflection or refraction. The phenomenon is observed in association with developing thunderstorm cells, where the cloud's anvil or dome-shaped extensions become prominently lit against the sky. As a purely passive optical effect, crown flashes involve no self-emitted light from the cloud itself, relying instead on external solar illumination. Their infrequency arises from the precise geometric alignment needed between the observer, the sun, and the cloud's internal particles, making sightings uncommon even during suitable thunderstorms. This rarity is underscored by limited documented observations, often verified by multiple witnesses in specific locations like near Ann Arbor, Michigan, in 1970.

Visual Characteristics

Crown flash appears as a sudden brightening at the summit of a , manifesting as dynamic beams or arcs of light that flash, jump, flip, or dance across the cloud top. These luminous features often form twisting columns, loops, pillars, or rapid sweeps, creating an aurora-like or feather-like that ripples upward and outward from the point of initiation. The light is predominantly , reflecting direct , particularly when the display resembles elongated sun pillars known as jumping sundogs. The phenomenon is highly dependent on the observer's position relative to the sun and cloud, becoming visible only from specific angles where aligns precisely with the ice crystals at the cloud's . From these vantage points, the beams may exhibit jerking or dancing motions, giving the impression of an ethereal spotlight sweeping the sky, with durations ranging from fractions of a second to several seconds per event, though sequences can persist for up to a minute. As a purely optical effect, crown flash produces no audible sounds or thermal sensations, distinguishing it as a silent, visually striking display above active thunderstorms.

Occurrence and Observations

Environmental Conditions

Crown flash requires the presence of mature cumulonimbus clouds with strong vertical development, typically reaching altitudes where temperatures are sufficiently low to support the formation of ice crystals at or above the cloud top. These clouds, often in their mature stage of thunderstorm evolution, provide the necessary charged environment and structural height for the phenomenon to manifest. The event occurs exclusively during daylight hours, with optimal visibility when the sun is positioned at a low relative to the horizon, as this configuration enhances the reflection and of by the ice crystals. High-altitude ice crystals, commonly found in the or spreading cirrus layers extending from the cumulonimbus top, play a critical role in enabling the optical effects observed. Crown flashes are more commonly reported in mid-latitude regions during convective seasons, particularly summer, when frequent and intense thunderstorms develop under unstable atmospheric conditions. Observations necessitate a clear line-of-sight from the observer to the illuminated top, free from obscuring lower-level clouds or . Proximity to activity within the is a key influencing factor, as discharges perturb the local and trigger the alignment of ice crystals, though the phenomenon bears no direct relation to the height of the or the specific type of , such as or , occurring at lower levels.

Notable Sightings

One of the earliest widely shared videos of a crown flash was captured in , on June 21, 2015, by a motorcyclist who filmed a dynamic beam of emanating from a thundercloud, initially mistaken for an extraterrestrial sighting. In 2016, a striking example occurred in the Moscow region of , where footage showed a sweeping streamer just prior to a discharge, highlighting the phenomenon's association with activity. A particularly vivid instance was recorded in in May 2022, featuring a prominent beam of projecting from clouds near a , described as a spectacular display due to its intensity and visibility. In April 2023, a crown flash over , gained significant attention through a that amassed over 618,000 views on , showing a flashlight-like beam dancing across the cloud tops. More recently, on June 21, 2025, an impressive crown flash was documented over Anniston and , via video, capturing erratic light rays from a developing . Documentation of crown flashes has increased markedly, coinciding with the rise of platforms like and , which have enabled the sharing of amateur footage. No injuries, fatalities, or direct hazards have been associated with these optical events, as they pose no physical risk beyond the underlying conditions. Crown flashes are often misidentified as UFOs, lights, or other anomalies, contributing to their mystique, and they are best observed from ground level or low altitudes where the alignment of ice crystals with the observer's is optimal.

Historical Background

Early Descriptions

The earliest scientific account of the crown flash phenomenon was published in the Monthly Weather Review in 1885, describing it as a sudden brightening around the tops of cumulonimbus clouds during thunderstorms. This report is recognized by as the first documented scientific description of the event, marking its initial entry into meteorological literature. In the broader 19th-century context, anecdotal reports from ground observers of unusual light effects near thunderclouds were common but largely dismissed by scientists as optical illusions or misperceptions, lacking the means for verification such as , which was not yet widely used for such transient atmospheric events. These early sightings often appeared in weather logs without formal analysis, contributing to the phenomenon's obscurity until the 1885 publication. Initial misconceptions frequently led observers to confuse crown flashes with auroras due to their streamer-like appearance emanating from tops, as both involved unexplained luminous displays in stormy conditions. The visual similarity to auroral displays, noted even in the description, reinforced such interpretations in pre-modern records. The phenomenon was later linked to involvement at tops, though early accounts emphasized only the observed brightening without mechanistic explanation.

Modern Documentation

Modern documentation of crown flash has advanced significantly since the mid-20th century, transitioning from initial qualitative observations to more structured scientific inquiries and widespread visual recordings. In 1965, proposed an explanation linking the phenomenon to electrical effects in thunderstorms, suggesting that rapid changes in the atmospheric could reorient ice crystals in the cloud top, producing the observed brightening; this hypothesis was published in the journal as "Orientation of Ice Crystals in the Electric Field of a " and marked an early attempt to move beyond mere descriptions toward testable mechanisms. Building on this, a 1971 article in by John C. Gall Jr., Maurice E. Graves, and Vonnegut detailed a ground-based of crown flashes occurring concurrently with strokes in a , describing the sudden brightening and subsequent aurora-like streamers while noting the potential role of ice crystals in the cloud environment. This publication, along with an earlier 1971 Nature note by Gall and Graves titled "Possible Newly Recognized Meteorological Phenomenon called Crown Flash," represented a key step in hypothesis testing by correlating the flashes with electrical activity and advocating for further instrumentation to capture the events. The advent of digital technology has greatly facilitated documentation, with amateur videos emerging as a primary tool for capturing crown flashes since around 2009; compilations on platforms like have preserved numerous instances, allowing researchers to analyze the phenomenon's dynamics retrospectively. From 2015 onward, has amplified sharing of these sightings, including high-resolution captures from smartphones and drones, which have provided clearer views of the flashes' rapid movements over locations such as the and , though no dedicated satellite observations have been reported to date. This evolution reflects a broader shift in atmospheric research, from anecdotal and qualitative reports to empirical validation through visual and electrical data, underscoring the rarity of crown flash despite increased documentation efforts. In the 2010s, the Guinness World Records officially recognized the 1885 publication in Monthly Weather Review as the first scientific description, highlighting the phenomenon's historical significance amid modern interest.

Scientific Explanation

Electric Field Effects

Thunderclouds, particularly cumulonimbus formations, generate strong vertical electric fields through charge separation processes involving ice particles and supercooled water droplets within the cloud. These fields typically range from 10 to 100 kV/m in strength and can extend upward to the upper ice layers of the cloud, where anvil cirrus forms. The charge separation arises primarily from collisions between graupel and ice crystals in the mixed-phase region, with positive charges accumulating in the upper portions and negative charges lower down, establishing a dipole structure. Perturbations in these occur due to discharges or intracloud charge redistributions, which rapidly alter the field configuration over fractions of a second. Such changes induce temporary electric dipoles in particles suspended in the upper regions, though the fields themselves do not directly emit . Historical observations link these field dynamics to variations in brightness, as proposed in early studies of . Field strengths around 10 kV/m serve as a threshold for aligning small ice particles against aerodynamic forces in thunderstorms, with stronger fields (100 kV/m or more) affecting larger crystals. Bernard Vonnegut's 1965 analysis highlighted how such electric fields in thunderclouds influence ice crystal orientation, providing a foundational connection to transient atmospheric optical effects. These perturbations briefly alter crystal alignments, contributing to the initiation of phenomena like crown flash without involving direct luminescence from the field.

Ice Crystal Dynamics

Ice crystals involved in crown flash phenomena are typically plate-like or columnar in shape, with dimensions ranging from several micrometers to over 100 micrometers, forming in the upper regions of cumulonimbus clouds through vapor deposition or freezing of supercooled droplets. These crystals exhibit a nature due to their hexagonal structure, which permits the induction of electric dipoles when subjected to atmospheric of sufficient strength, such as those around 4-5 kV/m near thunderstorm tops. The induced dipole moment arises from the separation of charges within the crystal lattice under the field's influence, enabling the crystals to respond as polarizable particles. The alignment process occurs as the exerts a on the induced , qualitatively described by the interaction where the magnitude depends on the dipole moment, field strength, and angle between them, prompting the to rotate toward alignment with the field lines. Plate-shaped crystals tend to orient their flat faces horizontally, while columnar ones align vertically along the field direction, a configuration that minimizes the of the dipole-field system. Upon reversal or perturbation of the field—often triggered by nearby discharges—the crystals reorient rapidly, with the process taking on the order of 0.5 seconds, leading to collective oscillations at frequencies of 1-2 Hz across a volume of crystals. This reorientation involves tilting of 8-12 degrees and gyration, resulting in conical motion of the crystal axes and synchronized motion among nearby crystals. Optically, the aligned crystals function as oriented scatterers, preferentially refracting and reflecting into narrow beams due to their uniform orientation, which enhances and along the beam direction. The rapid tumbling and reorientation during field changes disrupt this alignment momentarily, causing the reflected and refracted light intensity to flicker as the crystals reflect and refract differently in their transitional states, producing the dynamic, pulsing visual effects characteristic of crown flash. This collective response amplifies the optical variability, with the flickering visible at rates matching the field's .

Similar Atmospheric Optics

Crown flash shares optical mechanisms with several other atmospheric phenomena primarily involving the interaction of with ice crystals suspended in the air. Light pillars, for instance, manifest as vertical beams of light extending above or below the sun or , resulting from the reflection of off the flat faces of horizontally oriented plate-shaped ice crystals that slowly fall through the atmosphere. These crystals, typically found in high-altitude cirrus or cirrostratus clouds during cold , align parallel to the ground, creating the pillar effect when the sun is low on the horizon. Phenomena like light pillars and sundogs generally occur in cold, stable atmospheric layers with low , where crystals form and persist without rapid melting. Sundogs, or parhelia, appear as bright, colored spots on either side of the sun, about 22 degrees away, caused by the of sunlight through hexagonal plate crystals that act as prisms. These plate crystals, with their 60-degree prism angles, bend light rays outward, producing a of colors with nearest the sun and blue on the outer edges; they form in cold, clear air containing supercooled droplets that freeze into crystals near clouds. A dynamic variant, jumping sundogs, exhibits rapidly moving or flickering light patches, akin to the transient nature of crown flash, where may orient and reorient ice crystals, altering their reflective paths in real time. In contrast, auroras represent an electrically driven light display, generated when charged solar particles collide with atmospheric gases, exciting them to emit light without relying on crystal or reflection. Crepuscular rays, meanwhile, arise from the scattering of sunlight by dust, smoke, or water droplets through gaps in clouds, creating perspective-converging beams that appear to radiate from a point, distinct from crystal-mediated .

Key Distinctions

Crown flash is fundamentally distinct from , as it represents a passive optical of by ice crystals rather than an active electromagnetic emission from electrical discharge. While produces intense, omnidirectional illumination accompanied by thunder and potential ionization, crown flash manifests as transient brightening or streamers at the cloud top, visible only when the sun illuminates the scene from a specific angle and lacking any associated sound or heat. This observer-dependent visibility arises from the reorientation of plate-like or columnar ice crystals in response to fluctuating near the thundercloud, a process triggered but not equivalent to the lightning stroke itself. In contrast to the aurora, which generates its own through the excitation of atmospheric gases by charged particles from solar activity, crown flash involves no intrinsic emission but solely the reflection and of existing . Auroral displays often exhibit , , or hues due to specific lines and occur at high altitudes in polar regions, independent of local storms, whereas crown flash is localized to the upper portions of cumulonimbus clouds and retains the white or yellowish tint of direct solar . Crown flash also differs markedly from ball lightning and misidentified UFO sightings, as it lacks the spherical shape, thermal energy, audible reports, or autonomous movement through space typical of those rare or debated phenomena. Instead, the effect remains fixed to the or dome of the thundercloud, with no of plasma formation or extraterrestrial origin, and is fully explained by . Unlike free-floating , which may persist for seconds to minutes and interact with surfaces, crown flash episodes are brief (lasting fractions of a second to several seconds) and tied directly to the cloud's structure. Finally, crown flash stands apart from other atmospheric optical flashes, such as standard halos or sundogs, by requiring dynamic variations to induce rapid crystal reorientation—conditions absent in the stable, field-free environments that produce those static effects. Conventional halos form from fixed orientations of ice crystals refracting sunlight at consistent angles (e.g., 22° or 46°), resulting in persistent rings or parhelia, whereas the electric dipole moments in crown flash cause tilting and chaotic alignments, yielding fleeting, beam-like or rippling displays. This electric influence, unique to electrified storm regions, underscores the phenomenon's reliance on dynamics rather than uniform optics.

References

  1. https://www.guinnessworldrecords.com/world-records/400050-first-description-of-a-crown-flash
  2. https://www.nature.com/articles/231258a0
  3. https://ojs.bonviewpress.com/index.php/JOPR/article/view/4594
  4. https://doi.org/10.1038/229184b0
  5. https://doi.org/10.47852/bonviewJOPR52024594
  6. https://www.nature.com/articles/229184b0
  7. https://slate.com/technology/2016/11/video-of-a-crown-flash-in-russia.html
  8. https://www.oregonlive.com/weather/2015/06/space_aliens_have_arrived_amaz.html
  9. https://www.yourweather.co.uk/news/trending/crown-flash-rare-phenomenon-captured-in-the-usa-weather-light.html
  10. https://www.newsweek.com/video-captures-rare-crown-flash-skies-above-miami-1797481
  11. https://www.facebook.com/spannwx/videos/crown-flash/1431504111190106/
  12. https://www.washingtonpost.com/news/capital-weather-gang/wp/2015/06/25/this-video-is-proof-that-aliens-exist-just-kidding-its-a-crown-flash/
  13. https://doi.org/10.1002/j.1477-8696.1965.tb02740.x
  14. https://www.youtube.com/playlist?list=PLS8LbL7GIZiDcEf_E4GWRwKbx3fIFpW0p
  15. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JD031433
  16. https://www.sciencedirect.com/science/article/abs/pii/S0169809501000898
  17. http://amasci.com/amateur/vonngt_1965.html
  18. https://repository.tudelft.nl/file/File_27d5e31b-efe8-4cda-837b-28800cb287d4
  19. http://www.cmsim.eu/papers_pdf/april_2018_papers/April_3_2018_CMSIM_Tufaile_et_al_159-171.pdf
  20. https://rmets.onlinelibrary.wiley.com/doi/10.1002/j.1477-8696.1965.tb02740.x
  21. https://www.weather.gov/arx/why_halos_sundogs_pillars
  22. https://rammb.cira.colostate.edu/dev/hillger/optical-phenomena.htm
  23. https://www.mdpi.com/2410-3896/5/3/45
  24. https://science.nasa.gov/sun/auroras/
  25. https://slate.com/technology/2015/06/crown-flash-electric-cloud-phenomenon-makes-light-dance.html
  26. https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.3247
Add your contribution
Related Hubs
User Avatar
No comments yet.