Transient Luminous Events (TLEs) are optical phenomena that occur in the upper atmosphere of Earth. These events are characterized by brief and dynamic bursts of light, often appearing as luminous flashes, glows, or discharges. TLEs typically occur above intense thunderstorms and are associated with lightning activity.
There are several types of TLEs, including:
Sprites: These are large-scale electrical discharges that extend upward from the tops of thunderstorms. Sprites appear as clusters or columns of red, orange, or pink light, reaching altitudes of 50 to 90 kilometers (30 to 55 miles) above the Earth's surface. They are relatively short-lived, lasting only a few milliseconds.
Blue Jets: Blue jets are high-reaching discharges that propagate from the top of thunderstorm clouds in a cone shape. They can extend up to approximately 50 kilometers (30 miles) in altitude. Blue jets are characterized by their bluish color and can last for fractions of a second.
Elves (Emissions of Light and Very Low-Frequency Perturbations due to Electromagnetic Pulse Sources): Elves are rings or halos of light that occur in the upper atmosphere above thunderstorms. They are predominantly red in color and expand outward in a circular or doughnut-shaped pattern. Elves are extremely brief, typically lasting only a few milliseconds.
TLEs are challenging to observe due to their short duration and occurrence at high altitudes. They were discovered relatively recently with the aid of high-speed cameras and low-light imaging technology. The study of TLEs provides valuable insights into the electrical and atmospheric processes occurring in thunderstorms and their interaction with the upper atmosphere.