Origins of Extreme Lightning

Some flashes break the mold of what lightning is considered to be. They may extend over large distances or last for many seconds. Here, we explore the types of lightning flashes that live in the fringes of the LIS data. While the longest propagating flashes are enormous anvil crawlers, the largest flashes owe their extreme footprints to reflections off of lower cloud decks, and the longest-lasting flashes are actually convective cells with such high flash rates that they are constantly illuminated while TRMM is overhead.

The World Meteorological Organization recently accepted new records for the greatest length and duration of a lightning flash. These extreme flashes were observed by Lightning Mapping Array (LMA) networks that use radio emissions to trace the path lightning takes through the cloud.

Optical instruments such as the Lightning Imaging Sensor (LIS) measure the evolution of lightning from orbit by recording the light that escapes the top of the cloud. For many flashes, the optical signals reveal similar patterns of development to what is seen by LMAs. Though lightning imagers provide a limited picture of flash structure, their unparalleled global view is valuable for studying lightning phenomena in remote and data sparse regions.

This study identifies the most exceptional lightning flashes detected by LIS on the Tropical Rainfall Measuring Mission satellite and examines their optical structure, energetics, and evolutions. The longest optical flashes are shorter than the LMA records but still depict lateral development over a 50–100 km distance. The longest‐lasting LIS flashes rival the LMA record at 4–7 s. Notable examples of LIS flashes with radiant optical pulses (“superbolts”), flashes with many visible branches, and flashes that contain clusters of nearly continuous illumination are also identified.