A lightning strike of unprecedented distance, recognized as 'Megaflash', reportedly surpassed 500 miles, breaking a previous record according to research findings.
In a groundbreaking study titled "Megaflash lightning," a team of scientists, led by Randy Cerveny, a professor of geographical sciences at Arizona State University, delved into the mysteries of record-breaking lightning bolts. The findings were published in the Bulletin of the American Meteorological Society on Thursday.
The study sheds light on the phenomenon of megaflashes, which are not typically associated with the intense cores of storms but rather form in the weaker, outer parts. Megaflashes form under specific conditions found in long-lasting, electrically active thunderstorms, particularly in mesoscale convective systems (MCS) over regions like the U.S. Great Plains and southeastern South America.
Key conditions include severe thunderstorms with strong updrafts that carry rain and ice particles to various altitudes. These particles, by colliding, generate and transfer electrical charges inside the storm clouds. The vertical extent of the storm’s convective cells is limited, generally not rising beyond about 11 km (the top of the troposphere). When charged particles can no longer continue upward, they spread out horizontally, creating very large, thin, horizontally extensive charged layers. These expansive charged layers are crucial for megaflash formation.
Megaflashes occur in large, organized storm systems with extensive cloud layers and complex cloud-to-ground lightning interaction. They are rare events, occurring in less than one percent of thunderstorms. Satellite observations, such as from NOAA’s GOES-16, have shown megaflashes spanning hundreds of kilometers, with multiple ground strikes spread across vast areas.
The expansiveness of the storm is likely the primary driver of megaflashes, as smaller storms can't support as much horizontal travel. Megaflashes represent a worst-case lightning scenario due to their potential to spark wildfires or cause damage far from a storm's core.
Interestingly, megaflashes often form after the storm has moved on. This was evident in the 2017 megaflash that traveled 515 miles from eastern Texas to Kansas City, Missouri. The 2020 lightning bolt of 477 miles is now surpassed by this record-breaking event.
Understanding the conditions that allow megaflashes to occur at these scales is crucial for public safety, according to the study's lead author, Michael Peterson. Correcting the misconception that lightning can strike "out of the blue" is also important for public safety, as many lightning injuries occur because people underestimate the distance a bolt can travel from a storm and the duration of the danger.
As scientists continue to analyze data from satellite-based lightning mappers, which have only been operational for about 10 years, they expect to find more megaflashes. Chris Vagasky, a meteorologist with the National Lightning Safety Council, anticipates that the new datasets will help in understanding the location of lightning occurrences and the behavior of thunderstorms. The location of lightning occurrences is expected to be a key focus in future lightning research.
In summary, the combination of strong updrafts generating charged rain and ice particles, a large horizontally extensive but vertically thin charged region in the storm, and long-lasting organized thunderstorm systems create the conditions necessary for megaflashes. These findings provide valuable insights into the behaviour of these rare, powerful, and potentially dangerous phenomena.
- The study, focusing on megaflashes, underlines the importance of understanding environmental-science factors like severe thunderstorms, strong updrafts, and long-lasting organized storm systems, which contribute to their formation.
- In addition to shedding light on the science behind megaflashes, this research aims to correct misconceptions about lightning, emphasizing the need to account for their expansive travel capabilities and the continued danger even after a storm has moved on.
