Why in news?

Volcanic lightning captured public attention after an educational project brought to life an eighteenth-century mechanical model of Mount Vesuvius. The project highlighted the dramatic electrical discharges that sometimes accompany volcanic eruptions. Volcanic lightning is an unusual and little-understood natural phenomenon, and renewed interest prompted scientists to explain its causes and historical observations.

Background

• Volcanic lightning occurs during explosive eruptions when ash, rock fragments and ice particles are ejected into the atmosphere. The violent mixing of particles creates static electrical charges similar to those in a thunderstorm.
• It was first described by Roman author Pliny the Younger after the catastrophic eruption of Mount Vesuvius in 79 AD. Italian physicist Luigi Palmieri later documented several instances of the phenomenon in the nineteenth century.

How does volcanic lightning form?

• Collision of ash particles: Friction between ash and rock fragments within the eruption plume causes electrons to be transferred from one particle to another. This separation of charge produces static electricity.
• Ice charging: Higher in the plume, water vapour from the magma condenses into ice. Collisions between ice particles build up additional electric charge, leading to lightning strikes at higher altitudes.
• Fractoemission: When rocks break apart during an eruption, the cracks can release charged particles that contribute to the electric field.
• The combined effect of these processes results in brilliant bolts of lightning within the ash cloud, often visible from many kilometres away.

Significance

• Volcanic lightning provides clues about the intensity and dynamics of an eruption. Monitoring lightning can help scientists track ash plumes and provide early warnings for aviation safety.
• The phenomenon demonstrates the complex interplay between volcanic activity and atmospheric electricity, offering insights into both fields.

Sources: SciTechDaily