On May 23rd, an enormous swarm of sprites flickered and danced across the top of a thunderstorm in Oklahoma. Almost 400 miles away in New Mexico, amateur astronomer Thomas Ashcraft trained his cameras on the display. He captured the sprites--and something more:

"Note the dendritic upward spray in the midst of the sprite cluster," points out Ashcraft. "That is a possible 'pop-through gigantic jet'--a rare event."

Ashcraft has posted a video of the event with VLF-ELF radio emissions he recorded as a soundtrack. Turn up the volume: "The deep bass sound of the lightning stroke sounds like a distant shotgun blast in the night," he says.

What is a pop-through gigantic jet? Lightning scientist Oscar van der Velde of the Technical University of Catalonia explains: "A cluster of sprites can actually warp Earth's ionosphere, bringing it down from its usual altitude of 90 km to only 40 km." This sets the stage for the jet.
"The sprite cluster triggers an upward-directed discharge which in the past received fancy names as 'troll' or 'palm tree'," says van der Velde. "A satellite-based study by Taiwanese researchers in 2012 found them similar to gigantic jets--large isolated discharges reaching from the thundercloud toward the ionosphere. In case of a 'pop-through gigantic jet,' the lowering of the ionosphere is not uniform and the jet may then reach higher than the bottom tendrils of the sprite".

Although sprites have been seen for at least a century, most scientists did not believe they existed until after 1989 when sprites were photographed by cameras onboard the space shuttle. Now "sprite chasers" routinely photograph sprites--and more!--from their own homes. "They are easily detected by certain cameras," says van der Velde, "and if a storm is in the mood, you may record one every few minutes."    www.spaceweather.com

Yesterday [see below], we reported a rare apparition of sprites above Hurricane Hilda. Steve Cullen, who lives in Hawaii where the storm is heading, spotted them in a video from the Canada-France-Hawaii Telescope CloudCam atop Maunakea. A closer look at the video, however, reveals that the dancing forms were not sprites. Instead, Hurricane Hilda has gigantic jets.

Think of them as sprites on steroids: Gigantic jets are lightning-like discharges that spring from the tops of thunderstorms, reaching all the way from the thunderhead to the ionosphere more than 50 miles overhead. They're enormous and powerful.

"Gigantic jets are much more rare than sprites," says Oscar van der Velde, a member of the Lightning Research Group at the Universitat Politècnica de Catalunya. "While sprites were discovered in 1989 and have since been photographed by the thousands, it was not until 2001-2002 that gigantic jets were first recorded from Puerto Rico and Taiwan." Only a few dozen gigantic jets have ever been seen, mostly over open ocean.

Because gigantic jets are so rare, researchers are paying special attention to Hurricane Hilda. "Observations in recent years suggest that large thunderstorm clusters embedded in tropical cyclones harbor favorable conditions for gigantic jets. Hilda seems to confirm this. Extreme turbulent mixing in the storm top may assist in triggering these events," he says.
www.spaceweather.com

On August 10th, the National Weather Service reported an intense outburst of lightning from Hurricane Hilda in the Pacific Ocean. Steve Cullen lives in Waikoloa, Hawaii, where the storm is heading, and when he heard the report he had an idea. Cullen explains: "I wondered if the storm was close enough to be captured by the Canada France Hawaii Telescope CloudCam atop Maunakea. After sunset I logged on to the CloudCam site to check the most recent two-hour timelapse loop, and sure enough, WE HAD SPRITES!!!" Here are some frames from the video:

Sprites are a strange and beautiful form of lightning that shoot up from the tops of electrical storms. They reach all the way up to the edge of space alongside meteors, auroras, and noctilucent clouds. Some researchers believe cosmic rays help trigger sprites, but this is controversial. In short, sprites are a true space weather phenomenon.

As awareness of sprites has increased in recent years, photographers have started to catch them dancing atop ordinary thunderstorms on a regular basis: photo gallery. Seeing sprites above a hurricane, however, is rare. Most hurricanes don't even have regular lightning because the storms lack a key ingredient for electrical activity: vertical winds. (For more information read the Science@NASA article "Electric Hurricanes" by Patrick Barry and Dr.Tony Phillips.) Clearly, Hurricane Hilda is not a typical storm.          www.spaceweather.com

Solar activity is extremely low. Nevertheless, space weather continues. High above thunderstorms in the American west, red sprites are dancing across the cloudtops, reaching up to the edge of space itself. Harald Edens photographed this specimen on July 18th from the Langmuir Laboratory for Atmospheric Research in New Mexico. 

"This colorful sprite occurred over a large thunderstorm system in northeast New Mexico and was visible to the naked eye," says Edens. "I took the picture using a Nikon D4s and a 50 mm f/2 lens at ISO 25600."

Inhabiting the upper reaches of Earth's atmosphere alongside noctilucent clouds, meteors, and some auroras, sprites are a true space weather phenomenon. Some researchers believe they are linked to cosmic rays: subatomic particles from deep space striking the top of Earth's atmosphere produce secondary electrons that, in turn, could provide the spark that triggers sprites.

Although sprites have been seen for at least a century, most scientists did not believe they existed until after 1989 when sprites were photographed by cameras onboard the space shuttle. Now "sprite chasers" regularly photograph the upward bolts from their own homes. Give it a try!       

http://spaceweather.com/

With the arrival of summer, thunderstorm activity is underway across the USA. We all know what comes out of the bottom of thunderstorms: lightning. Lesser known is what comes out of the top: sprites. "Lately there has been a bumper crop of sprites," reports Thomas Ashcraft, a longtime observer of the phenomenon. "Here is one of the largest' 'jellyfish' sprites I have captured in the last four years." The cluster shot up from western Oklahoma on June 23, so large that it was visible from Ashcraft's observatory in New Mexico 289 miles away:  (see video at : http://vimeo.com/99060196)

"According to my measurements, it was 40 miles tall and 46 miles wide. This sprite would dwarf Mt. Everest!" he exclaims.

Also in New Mexico, Jan Curtis saw a cluster of red sprites just one night later, June 24. "I've always wanted to capture these elusive atmospheric phenomena and last night I was finally successful."

Although sprites have been seen for at least a century, most scientists did not believe they existed until after 1989 when sprites were photographed by cameras onboard the space shuttle. Now "sprite chasers" regularly photograph the upward bolts from their own homes.

Ashcraft explains how he does it: "My method for photographing sprites is fairly simple.  First I check for strong thunderstorms within 500 miles using regional radar maps accessible on the Internet. There must be a locally clear sky to image above the distant storm clouds. Then I aim my cameras out over the direction of the thunderstorms (which will be hot red or purple on the radar maps) and shoot continuous DSLR exposures. I usually shoot continuous 2 second exposures but if there is no moon then I will shoot up to 4 second exposures. Then I run through all the photographs and if I am lucky some sprites will be there. It might take hundreds to usually  thousands of exposures so be prepared for many shutter clicks. I use a modified near infrared DLSR but any DLSR will capture sprites. Note that it does require persistence and a little bit of luck."

Inhabiting the upper reaches of Earth's atmosphere alongside meteors, noctilucent clouds and some auroras, sprites are a true space weather phenomenon. Now is a good time to see them.                        www.spaceweather.com

Some thunderstorms are so powerful that they create ripples in the atmosphere 80 to 90 km high, at the edge of space itself. In satellite images such storms look like a giant atmospheric bulls-eye. It turns out these ripples are also visible from the ground. Amateur astronomer Thomas Ashcraft recently photographed them over New Mexico:

"Over the past few years I have been photographing sprites above distant thunderstorms using an infrared camera," says Ashcraft. "It turns out that the strong thunderstorm systems that generate sprites often also perturb the mesosphere and create gravity waves."

"This near infrared image from June 05, 2014, shows gravity waves above a powerful thunderstorm cell over western Kansas. The storm was about three hundred miles away from my observatory so the thunderstorm itself was below my horizon."


"There are many stills of this phenomenon but not many time-lapses that show their complex motions," he says. "I posted a movie extract of the storm on vimeo. Note also the sprites that pop up sporadically."

"The mesosphere is not well studied and it holds much Nature yet to be discovered," concludes Ashcraft. "To me it is a vast ecological zone full of beauty."               http://spaceweather.com/

By A'ndrea Elyse Messer : May 7, 2014

Photograph of a sprite.   Image: H. H. C. Stenbaek-Nielsen

UNIVERSITY PARK, Pa. -- Atmospheric sprites have been known for nearly a century, but their origins were a mystery. Now, a team of researchers has evidence that sprites form at plasma irregularities and may be useful in remote sensing of the lower ionosphere.

"We are trying to understand the origins of this phenomenon," said Victor Pasko, professor of electrical engineering, Penn State. "We would like to know how sprites are initiated and how they develop."

Sprites are an optical phenomenon that occur above thunderstorms in the D region of the ionosphere, the area of the atmosphere just above the dense lower atmosphere, about 37 to 56 miles above the Earth. The ionosphere is important because it facilitates the long distance radio communication and any disturbances in the ionosphere can affect radio transmission.

"In high-speed videos we can see the dynamics of sprite formation and then use that information to model and to reproduce the dynamics," said Jianqi Qin, postdoctoral fellow in electrical engineering, Penn State, who developed a model to study sprites.

Sprites occur above thunderstorms, but thunderstorms, while necessary for the appearance of a sprite, are not sufficient to initiate sprites. Not all thunderstorms and lightning strikes produce sprites. Recent modeling studies show that plasma irregularities in the ionosphere are a necessary condition for the initiation of sprite streamers, but no solid proof of those irregularities existed.

The researchers studied video observations of sprites, developed a model of how sprites evolve and disappear, and tested the model to see if they could recreate sprite-forming conditions. They report their results today (May 7) in Nature Communications.

Sprites resemble reddish orange jellyfish with bluish filamentary tendrils hanging down below.   Careful examination of videos of sprites forming showed that their downward hanging filaments form much more rapidly than in the horizontal spread, leading the researchers to suggest that localized plasma irregularities cause the streamers to propagate.

Read the entire article at:  http://news.psu.edu/story/314975/2014/05/07/research/sprites-form-plasma-irregularities-lower-ionosphere

Sept. 10, 2013:  We all know what comes out of the bottom of thunderstorms: bolts of lightning. Jagged columns of light plunge Earthward, heating the air to 50,000 degrees F, about five times hotter than the surface of the sun. Claps of thunder announce this process somewhere on Earth as often as 50 times a second. Have you ever wondered, though, what comes out of the top?

In recent decades researchers have discovered some strange things happening in the cloud tops.  High above ordinary lightning, exotic forms known as red sprites and blue elves shoot toward the heavens, cold cousins to the fiery bolts below. In some places jets of antimatter fly upwards, triggering the detectors on NASA's orbiting high-energy observatories.  And as often as 500 times a day, Earth briefly mimics a supernova, producing a powerful blast of gamma-rays known as a Terrestrial Gamma-ray Flash or TGF.

No know knows exactly how these phenomena are related either to each other or to the lightning down below.

A new experiment called "Firestation" onboard the ISS aims to find out.  Firestation is a package of sensors designed to explore the links between TGFs, ordinary lightning, and sprites.

A new ScienceCast video explores the strange things coming from the tops of thunderstorms.

Read the full story at : http://science.nasa.gov/science-news/science-at-nasa/2013/10sep_firestation/

COLORFUL SPRITES OVER NEBRASKA: "August 12th was another successful night in our sprites campaign," reports Jason Ahrns of the University of Alaska Fairbanks. With a team of researchers from NCAR, he has been flying over the midwestern USA onboard a Gulfstream V in search of exotic forms of lightning. As they were photographing a thunderstorm over Nebraska, these six sprites appeared:

These remarkably beautiful discharges were red on top and purple on the bottom. "I really can't explain the color change," says Ahrns. "That's one of the things we hope to investigate with this campaign by capturing high speed spectra."

First documented in 1989 by scientists from the University of Minnesota who photographed strange flashes coming out of the tops of thunderstorms, sprites remain a mystery today. Neither their basic physics nor their effect on the surrounding atmosphere is well understood. "Do sprites have a large scale impact on the middle atmosphere?" asks Ahrns. "Sprites clearly represent some kind of transfer of energy, but is it on a scale that has a significant effect on the weather and climate? We can't answer that without studying them."

The ephemeral nature of sprites (they typically last no more than a few milliseconds) makes them tricky to study. Researchers on the NCAR Gulfstream capture sprites using Phantom cameras running at 10,000 frames per second. "One of the Phantoms has a diffraction grating in front of it to capture high speed spectra, which I don't think has ever been done before," notes Ahrns.

The prettiest pictures, though, come from Arhns' own camera, a dSLR that he mounts in the window of the airplane to capture "beauty shots." The image above is an example.
www.spaceweather.com

High above Earth in the realm of meteors and noctilucent clouds, a strange form of lightning dances at the edge of space. Researchers call the bolts "sprites," and they are as beautiful as they are mysterious. Jason Ahrns, a graduate student from the University of Alaska Fairbanks, photographed a cluster of bright red sprites over Oklahoma City on August 6th. Go to: http://www.flickr.com/photos/musubk/9448254067/  to view a rare high-speed movie of the phenomenon:

"I normally study auroras," says Ahrns, "but I've become involved in sprites as a side interest." At the time of the photo, Ahrns was flying onboard a Gulfstream V operated by the National Center for Atmospheric Research (NCAR). "We try to get off to the side of sprite-producing storms, ideally about 200 km away, and film them with a couple of Phantom cameras running at 10,000 frames per second. One of the Phantoms has a diffraction grating in front of it to capture high speed spectra, which I don't think has ever been done before."

"We've also managed to record a few sprites over a lightning mapping array so we can identify the exact lightning strike that caused the sprite," he continues. "This has also never done before, and should provide insight into what type of lightning causes sprites."

"Lately," says Ahrns, "I've begun slipping my personal camera into a spare window of the airplane, and the results have been so impressive that we're planning to make a dSLR (digital camera) a regular part of future campaigns. On August 3rd I recorded some blue jets over Oklahoma city; I believe these are the first blue jets recorded by an ordinary dSLR." More tales of sprite-chasing may be found on Ahrns' personal blog.                      www.spaceweather.com

High above Earth in the realm of meteors and noctilucent clouds, a strange and beautiful form of lightning dances at the edge of space. Researchers call the bolts "sprites"; they are red, fleeting, and tend to come in bunches. Jesper Grønne of Silkeborg, Denmark, photographed these specimens on August 15th:

"After several years of hunting sprites from my location in Denmark, I finally caught some last week--the first danish Red Sprites ever photographed," says Grønne. "They were located 50 km to 90 km above a thunderstorm some 350 km away over the North Sea. There were 2 flashes, each producing 5-6 individual Red Sprites."

"Sprites are a true space weather phenomenon," explains lightning scientist Oscar van der Velde of Sant Vicenç de Castellet, Spain. "They develop in mid-air around 80 km altitude, growing in both directions, first down, then up. This happens when a fierce lightning bolt draws lots of charge from a cloud near Earth's surface. Electric fields [shoot] to the top of Earth's atmosphere--and the result is a sprite. The entire process takes about 20 milliseconds."

Although sprites have been seen for at least a century, most scientists did not believe they existed until after 1989 when sprites were photographed by cameras onboard the space shuttle. Now "sprite chasers" routinely photograph sprites from their own homes. "I used an astro-modified Canon 5D II in video-mode to catch my sprites," says Grønne. Give it a try!
www.spaceweather.com

Sprites are electrical discharges that come out of the top of thunderclouds, opposite ordinary lightning bolts which plunge toward Earth. Sprites can tower as high as 90 km above ground. That makes them a form of space weather as they overlap the zone of auroras, meteors, and noctilucent clouds.   Because they are associated with lightning, sprites are most often seen in summer months, "but in the past few days sprites have been reported in Texas (particularly near the Mexican border) as well as here in New Mexico," notes Ashcraft.

So if there's lightning where you live, be alert for sprites.                                                                                     www.spaceweather.com