Sprites, Elves, Trolls, Pixies, Ghosts, Gnomes, and Blue Jets
No, we’re not traveling today to Middle-earth or into the belly of a dungeon crawler. Instead, we’ll take to the skies.
All the fantastical characters of today’s title are real phenomena in the upper atmosphere!
Most of us are familiar with the visuals of a lightning storm. The intense brightness and the clap of the electrostatic discharge of thunderclouds together produce one of the indelible images of our world and universe. Lightning strikes occur in three ways. The most famous is the cloud-to-ground bolt, though lightning can also occur from one cloud to another or within a single cloud. The bolts simply require two oppositely charged regions.
But what happens above thunderclouds?
Despite the common occurrence of lightning hitting the planet beneath its parent storm, a physicist named C.T.R. Wilson predicted in 1925 that electrical breakdown should happen above thunderstorms (Wilson won a Nobel prize in physics for inventing the cloud chamber). Electrical breakdown is the scientific term for the process in which a material that usually does not conduct electricity (insulator) suddenly experiences electrical flow, usually thanks to a voltage high enough to overcome the material’s insulating properties.
In the early years of aviation, pilots reported high-altitude discharges. However, many meteorologists dismissed the claims, despite Wilson’s prediction and various firsthand sightings over previous centuries. Not until scientists from the University of Minnesota accidentally snapped low-light images of a “large upward electrical discharge” above a thunderstorm in 1989 did the weather world realize what happened above the clouds!
The Minnesota scientists had stumbled upon the first hard evidence for sprites. Several years after that video capture, scientists coined the name after the carbonated beverage, er, the elusive, mischievous air spirits of folklore, such as Shakespeare’s famous Puck and Ariel. Sprites are typically red to red-orange and sometimes feature blue tendrils that hang below the main body. Scientists have classified three types of sprits: Jellyfish (large, up to 50 kilometers by 50 kilometers), Column (C-sprite; tend to move upward), and Carrot (C-sprite with “roots” that hang down).
Because sprite wasn’t good enough on its own, meteorologists created an acronym to go with it: Stratospheric/mesospheric Perturbations Resulting from Intense Thunderstorm Electrification.
Since the first documented sprite in 1989 and the first color image, taken in 1994, sprites have emerged as the most common form of upper-atmospheric lightning or transient luminous events (TLEs). Sprites are visible all over the world from the ground, if we’re lucky, but have become star performers for the International Space Station. The ISS is often in the perfect location to see both a lightning strike and the sprite above it.
Once we discovered sprites, the fairies were out of the Midsummer bag. Now, we knew where to look; were there other electrical phenomena flashing across the atmosphere?
Since you already read the title of the article, you know the answer is a fat yes!
ELVES (Emission of Light and Very Low Frequency perturbations due to Electromagnetic Pulse Sources) are dim and flattened areas of glowing, typically about 400 kilometers wide, that last a millisecond. Elves live really high in the sky, 100 kilometers up, typically, in the ionosphere. Elves are so ephemeral that scientists are not certain yet about their color, but think they are red like sprites. The space shuttle Discovery detected the first elf in 1990. They appear on film like a large, horizontal flash.
Then you have your Trolls. Another acronym: Transient Red Optical Luminous Lineaments. Trolls form after sprites. They appear in the form of a red spot with faint tails, finishing their existences with a red streak downward from its dot.
Pixies are, fittingly, tiny. They appear as single points of brilliant white. Pixies tend to arrive randomly and scientists do not believe they are tied to any specific lightning strike, though they do emerge over thunderstorms.
Gnomes are also on the smaller end of upper-atmospheric lightning. Like pixies, they are white, but, unlike pixies, they are not points, but spikes that emanate upward from the anvil of large thunderheads. They last for mere microseconds.
Pixies and Gnomes do not have cool acronyms.
The newest member of the paranormal stable, however, does have a cool acronym. Ghosts are Green emissions from excited Oxygen in Sprite Tops. Now that I look at it, they’ve cheated and inserted an “H” that does not feature in the long-form name. Uncool. Back in the cool realm, though, are the ghosts themselves. They form after sprites, at their tops. Scientists speculate ghosts are excited oxygen particles, whereas sprites tend to excite nitrogen. Check out this incredible video for some science behind it, incredible imagery, and the documentation of the discovery of Ghosts.
These transient luminous events entered my life the other day thanks to a notification from The Weather Channel about the rarest form of the phenomena and, in my opinion, perhaps, the neatest. A photographer named Lori Grace captured blue jets during a thunderstorm in Arizona.
Jets are brighter than sprites and the other LTEs and, as the name implies, a shade of brilliant blue. Like a lot of the others, blue jets were first spied by a space shuttle in 1989. In the first 20 years of research on blue jets, only a few hundred images were captured and a majority of those were from a single thunderstorm. That storm had been targeted for the purpose by aircraft. Since then, the ISS has focused on searching for blue jets and has nabbed a good number of great photos. Seeing them is still quite rare from the ground, so when a human with feet on earth snags a photo it becomes big news.
Blue jets come in three sizes: starters, jets, and gigantic jets. The upward tournament brackets of the blue jets are awe-inducing; the scale of a gigantic jet nears unimaginable.
I tell you what: blue just does it for me.
Thunderstorms have always held a special sway over my imagination. The sounds, the light shows, the power. I never realized they held even more wonder in the parts we can’t always see. These transient luminous events are entrancing to watch. I could dump footage on you for hours. If they strike your fancy, I urge you to keep looking into them. You won’t be disappointed!
Further Reading and Exploration
Blue Jets Captured in Thunderstorms Over Arizona-Mexico Border – The Weather Channel
Sprites and Their Siblings – Thought Co.
Once Upon a Time in a Thunderstorm – NASA
The Role of the Space Shuttle Videotapes in the Discovery of Sprites, Jets, and Elves – NASA
Recent Blue Jet Photography – Lori Grace