Satellite Spider Lightning Flashes
© Michael Peterson
Satellites detect lightning by measuring the light produced by the flash that escapes the top of the cloud. Lightning imagers have been added to satellites and the International Space Station in low-Earth orbit that provide snapshots of the lightning in thunderstorms across the globe. Building on the success of these instruments, the Geostationary Lightning Mapper (GLM) on the GOES-16 satellite is the first lighting imager in geostationary orbit that continuously detects lightning activity across the western hemisphere.
Lightning imagers tell us more about lightning than simply whether a flash occurred. They measure the evolution of the optical energy produced by individual flashes at 500 frames per second. We can use this information to characterize lightning flashes and study the underlying physics of lighting discharges. This video shows a spider lightning flash observed by the Lighting Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite - a predecessor to GLM. It traces the lateral development of the optical energy of the flash as it evolves along its various branches.
The CICS-MD Scientist Michael J. Peterson and the lightning group at ESSIC quantifies flash structures such as these to improve situational awareness of the hazards posed by thunderstorms observed by GLM. The shape, energy, and structure of lightning depend on the organization of the parent thunderstorm. For example, spider flashes like the one in this video typically occur in electrified stratiform regions of mature Mesoscale Convective Systems (MCSs). Classifying GLM flashes by their shapes, sizes, and energetics provides insights into convective processes in electrified weather that are helpful to forecasters.