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© Thomas AshcraftAshcraft captures a large sprite hanging over West Kansas.
(Click here to watch the video)

In the blink of an eye, an enormous bright red light flashes above a thundercloud, spreading energetic branches that extend five times taller than Mount Everest and look like jellyfish tendrils and angel's wings.

These mysterious phenomena are known as Transient Luminous Events (TLEs), and are usually invisible to the naked eye because they happen on millisecond timescales, too fast to be seen. They occur between 50 to 100 kilometers above the ground, a long-ignored area of the atmosphere that is too high for aircraft but too low for satellites to investigate. There, the thin air interacts with strong electrical fields to ionize molecules and create arcing plasmas.

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© Thomas AshcraftTwo sprites burst on the scene above Oklahoma.
Using a relatively simple camera and radio dish, Ashcraft has seen a whole bestiary of odd TLE phenomena. The most common are sprites, tall and highly structured bursts of light that appear above thunderstorms. They ionize the nitrogen in our atmosphere, causing a red glow. Often, they happen in conjunction with "Emissions of Light and Very Low Frequency Perturbations due to Electromagnetic Pulse Sources," also known as ELVES, which are enormous halos of light that shoot outward to cover up to 500 kilometers in a millisecond. Though they are too short-lived to see, ELVES can produce bright afterglows that some people have mistaken for UFOs. Other TLEs have names like blue jets and trolls.
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© Thomas AshcraftThe long tendrils from a sprite can be seen in this video, which captures an incident above Amarillo, Texas in 2012.
(Click here to watch the video)

To deliver great TLE shots, Ashcraft first checks radar maps of the local area around his observatory in Santa Fe, New Mexico. Red spots on such maps indicate strong lightning cells, which increases the probability of sprite activity. Because the phenomena are mostly visible in near infrared wavelengths, he uses a modified off-the-shelf DLSR camera from which he removed the clear glass filter covering the CCD that blocks infrared light.
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© Thomas AshcraftA donut ELVE is an extremely powerful ELVE that has a hole in its center.
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By taking continuous three-second exposures, Ashcraft records thousands of pictures each night. He then goes through the catalog looking for a sprite to appear. If he spots something, he can check a video camera that he has running during the night to see if captured more detail there. He shares his most interesting findings with other sprite observers, who may chime in with their own pictures from other positions.
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© Thomas AshcraftA spectacular vista shows a tiny blip above a cloudbank. Ashcraft thinks the small flash is either a starter, a blue jet, or a gnome.
From Santa Fe, Ashcraft says he can usually catch sprites up to 1,000 kilometers away. "I can see big storms out over the Great Plains, usually beyond Oklahoma City and into Nebraska," he said. "After that, the curvature of the Earth gets in the way."
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© Thomas AshcraftThe forking nature of a sprite is evident in this image, taken above a storm east of Las Vegas in 2012.
Using a radio dish, Ashcraft also captures extremely low frequency emissions that the TLEs give off. He converts these into sound files, which can be heard in his videos, and can help researchers pick out details they might otherwise miss.
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© Thomas AshcraftA zoomed-in image showing a cluster of sprites.
A lot of research regarding TLEs is still cutting-edge science, said Ashcraft. Only in recent years have scientists aimed high-speed cameras capable of capturing thousands of frames per second to study the spectacles in detail. While researchers had originally hypothesized that the phenomena were starting at the tops of thunderclouds, fast-motion videos prove that TLEs start as luminous spheres and then shoot upwards and downwards at the same time.
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© Thomas AshcraftAn amazing flash of sprites
(Click here to watch the video)

In this gallery, we take a look at some of Ashcraft's most spectacular TLE recordings to get a better appreciation of these weird and wonderful phenomena.
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© Thomas AshcraftA great bright sprite from a storm above Clovis, New Mexico.