What are Lightning Sprites?

Sprites were first reported anecdotally by pilots and scientists for decades but were officially documented in 1989 by researchers from the University of Minnesota who captured them on video.

Lightning sprites are large-scale electrical discharges that occur high above thunderstorms, often in the mesosphere at altitudes between 50 and 90 kilometers (31–56 miles). Unlike traditional lightning, which occurs within clouds or between clouds and the ground,

sprites are triggered by positive cloud-to-ground lightning strikes and have a unique reddish-orange glow due to ionized nitrogen molecules1. They are a transient luminous event (TLE) and are part of a broader category that includes blue jets, elves, and gigantic jets2. Sprites were first reported anecdotally by pilots and scientists

for decades but were officially documented in 1989 by researchers from the University of Minnesota who captured them on video. Since then, they have been extensively studied using high-speed cameras, satellites, and ground-based observations. The name “sprite” was coined due to their fleeting and ethereal nature, resembling mythical spirits.

A mythical spirit or sprite is a supernatural being often associated with nature, folklore, and legend, typically depicted as an ethereal, mischievous, or benevolent entity. Sprites are commonly found in European mythology, particularly in Celtic and Germanic traditions, where they are believed to inhabit forests, rivers, and other natural landscapes. They are closely related to fairies, elves, and nymphs, often portrayed as small, winged creatures that can influence human affairs, sometimes leading travelers astray or offering guidance. In literary works such as Shakespeare’s A Midsummer Night’s Dream, the sprite Puck embodies the playful and sometimes trickster-like nature of these beings. Sprites also appear in various mythologies worldwide, reflecting humanity’s deep connection with nature and the supernatural.

Sprites typically appear in clusters and exhibit various shapes, such as jellyfish-like forms, columns, and tendrils. Their duration is extremely short, often lasting only a few milliseconds. Unlike typical lightning, which carries high currents for short distances,

sprites involve weaker currents but extend over tens of kilometers. They occur in the upper atmosphere, where the lower pressure and different gas composition cause their distinct red and blue colors. Sprites form as a result of strong positive cloud-to-ground (CG) lightning discharges.

These discharges create an intense electric field in the mesosphere, which ionizes the thin atmospheric gases and triggers the luminous discharge. The process is known as dielectric breakdown, where the high-voltage difference causes the normally insulating air to become conductive. The breakdown releases energy in the form of visible light, creating the glowing structures seen from the ground or space. A sprite halo is a diffuse, disk-shaped luminous feature that often precedes the appearance of sprites.

It forms due to the initial electromagnetic pulse generated by the parent lightning strike, which momentarily ionizes a region of the upper atmosphere. Unlike sprites, halos are more uniform and lack distinct tendrils, but they play a crucial role in the sprite formation process.

Although sprites occur at altitudes above commercial air traffic (typically above 50 km), there have been concerns regarding their potential effects on high-altitude aircraft, space vehicles, and even satellites. While no major incidents have been definitively linked to sprites, the associated electromagnetic disturbances could, in theory, affect avionics or communication systems. Some researchers have suggested that more studies are needed to understand their full impact on aviation.

  • Sprites are often confused with other upper-atmosphere phenomena like blue jets and elves, but they have distinct formation processes and appearances.
  • NASA and other space agencies have captured sprite activity from orbit, providing valuable data on their properties and frequency.
  • Sprites were first captured in high-speed video in the early 1990s, leading to a rapid increase in scientific interest and study.
  • Some reports suggest that early civilizations may have witnessed sprites but lacked the means to explain or document them scientifically.
Footnotes
  1. Ionized nitrogen molecules are nitrogen (N₂) molecules that have lost or gained electrons due to high-energy interactions, such as electrical discharges, ultraviolet radiation, or cosmic rays. In the case of lightning sprites, the intense electric fields from thunderstorms excite and ionize nitrogen in the mesosphere, causing it to emit the characteristic red and blue glow observed in these transient luminous events. The ionization process occurs when an electron is stripped from a nitrogen molecule (forming N₂⁺) or when nitrogen atoms gain excess energy, leading to visible light emission as they return to a lower energy state. This phenomenon is crucial in atmospheric physics, auroras, and other high-energy atmospheric processes. ↩︎
  2. Blue jets, elves, and gigantic jets are transient luminous events (TLEs) that occur in the upper atmosphere during intense thunderstorms, distinct from traditional lightning. Blue jets are cone-shaped electrical discharges that originate at the tops of thunderclouds and propagate upward into the stratosphere, reaching altitudes of about 40–50 km. They are typically bluish due to ionized nitrogen emissions and differ from sprites in that they are not triggered by cloud-to-ground lightning. Elves (Emissions of Light and Very Low-Frequency Perturbations due to Electromagnetic Pulse Sources) are rapidly expanding, disk-shaped flashes that occur at around 90–100 km altitude, created by the electromagnetic pulses from powerful lightning strikes. Unlike sprites or jets, elves last only a millisecond and are much wider in scale. Gigantic jets are a rarer and more powerful variation of blue jets, extending from the top of a thundercloud to the ionosphere at altitudes of about 80–90 km. They bridge the gap between thunderstorms and space weather phenomena and have been observed to carry large electrical currents. These TLEs provide critical insight into the complex interactions between thunderstorms and the Earth’s upper atmosphere. ↩︎
Further Reading
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Author: Doyle

I was born in Atlanta, moved to Alpharetta at 4, lived there for 53 years and moved to Decatur in 2016. I've worked at such places as Richway, North Fulton Medical Center, Management Science America (Computer Tech/Project Manager) and Stacy's Compounding Pharmacy (Pharmacy Tech).

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