Transient Luminous Events (TLEs) are optical phenomena that occur in the upper atmosphere, specifically in the mesosphere and lower ionosphere. These events are brief, transient, and often visually striking, appearing as luminous flashes, glows, or other atmospheric discharges. TLEs are typically associated with thunderstorm activity and are observed above thunderclouds.
There are three main types of TLEs:
Sprites: Sprites are large-scale electrical discharges that occur above thunderstorm systems. They typically appear as reddish-orange, jellyfish-like structures with a branching, filamentary structure. Sprites are usually triggered by intense lightning discharges in thunderstorms and can extend upwards to altitudes of about 50 to 90 kilometers (30 to 55 miles) above the Earth's surface.
Blue Jets: Blue Jets are less common than sprites and are characterized by upward-directed electrical discharges originating from the top of thunderstorms. They appear as blue, cone-shaped jets that can reach altitudes of about 40 to 50 kilometers (25 to 30 miles).
Gigantic Jets: Gigantic Jets are even rarer and larger than sprites. They are similar to sprites but reach much higher altitudes, extending up to the lower edge of the ionosphere at approximately 90 kilometers (55 miles) above the Earth's surface.
TLEs are challenging to observe and study due to their transient nature and the fact that they occur at high altitudes. However, advancements in high-speed cameras and atmospheric research have allowed scientists to capture and study these phenomena in greater detail in recent years.