Transient luminous events: Sprites, Jets and Elves around the world

High above thunderstorms, red flames, blue streaks or sometimes circular doughnuts flash toward the sky.

These are real Transient Luminous Events (TLE) from different parts of the World.

All these visual phenomena are called transient luminous events (TLEs). They can happen in the blink of an eye and are extremely rare forms of upper-atmospheric electromagnetism.

Sprites, Jets and Elves

Transient luminous events can be broken down into sprites, jets and elves.

Red sprites appear high in the atmosphere, usually 25 to 55 miles above thunderstorms, with tendril-like structures that extend downward as far as 25 miles. They usually are associated with positively charged cloud-to-ground lightning strikes.

Atmospheric researchers have discovered that sprites are common above the decaying portion of large mesoscale convective systems but are rare above supercell thunderstorms.

Sprites are thought to occur due to ionization of the upper atmosphere above terrestrial lightning strikes. When a positively charged lightning bolt strikes the ground, it leaves the top of the thunderstorm negatively charged. When enough electric potential builds up, a discharge results in the form of a red sprite.

Blue jets are a visual phenomenon that propel upward from active thunderstorms. They can extend up to 12 miles from the top of the thundercloud, though they are not necessarily associated with a specific cloud-to-ground lightning strike. Atmospheric research indicates that blue jets only last one-tenth of a second, making them difficult to see with the naked eye. Scientists are still unsure as to what causes blue jets and how they form.

Elves are electromagnetic pulses generated by lightning strikes. Elves is an acronym for Emission of Light and Very Low Frequency Perturbations Due to Electromagnetic Pulse Sources. They look like doughnut-shaped flashes that spread laterally up to 186 miles. Atmospheric research indicates the brightness of elves is closely related to the peak current in a return lightning stroke (the movement of charges from the ground to the cloud), and that elves may be the most dominant type of TLEs in the atmosphere.

New transient luminous events are discovered every year, for a description of those pictured above and a full list of the ethereal phantoms visit the TLEs webpage of University of Albany-SUNY.

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