During powerful eruptions, ash, rock fragments and volcanic gases become electrically charged, producing spectacular lightning known as volcanic lightning or a "dirty thunderstorm"
Main claim
Volcanic eruptions can generate lightning within and around the eruptive plume as particles collide, fragment and separate electric charge, creating conditions for electrical discharges similar in some respects to those in thunderclouds.
Generation mechanisms
Two primary mechanisms explain plume electrification: triboelectric charging, where frictional contact between particles transfers charge, and fractoelectric charging, where breaking or fracturing of particles produces charge. Strong convective updrafts and, in colder plumes, the presence of ice can further enhance charge separation.
Appearance and range
Volcanic lightning can appear as frequent, rapid flashes inside the ash column or as long discharges extending from the plume to the surrounding atmosphere. In large eruptions these flashes are visible from many kilometres away and often create dramatic photographic sequences.
Scientific observations
Historical accounts describe luminous phenomena during eruptions, and modern instruments including high-speed cameras and electromagnetic sensors have confirmed that eruptive plumes carry significant electrical activity. Measurements help researchers infer particle concentration, fragmentation rates and plume dynamics.
Implications and hazards
Beyond their striking visuals, volcanic lightning poses extra hazards such as igniting fires on land and complicating monitoring and response efforts. The electrical signals also provide valuable data for volcano monitoring, aiding early detection of explosive activity and characterising plume behaviour.
Conclusion
In summary, volcanic lightning is a real and well-documented phenomenon caused by electrification of ash and other particles during eruptions. Often called a "dirty thunderstorm," it is both an impressive natural spectacle and an important subject of scientific study.