Volcanic lightning has very little to do with tectonic activity, and everything to do with everyday physics.Volcanic lightning is not formed deep in the Earth. It only forms in a volcanic plume, the cylinder-shaped column of volcanic ash emitted by some erupting volcanoes. Volcanoes that lack a thick volcanic plume usually lack volcanic lightning. Volcanoes in Hawaii, for instance, are more likely to eject fluid lava fountains than thick plumes of ash. These volcanoes rarely have volcanic lightning.The tiny particles that make up a volcanic plume are tightly compressed beneath a volcano. The airy atmosphere aboveground, however, is much less dense. This change in density contributes to volcanic lightning.As densely packed particles are violently ejected in a volcanic plume, they rub against each other. This interaction is called friction. Through friction, ash particles gain and lose electrons—they become electrically charged. As charged particles ascend the less-dense volcanic plume, the plume experiences charge separation. Positively charged particles become increasingly separated from negatively charged particles.When the charge separation becomes too great for air to resist the flow of electricity, lightning tears through the volcanic plume to connect the positively and negatively charged particles.Everyday LightningYou don’t need an actual volcano to get an idea of how volcanic lightning works. Friction creates charged particles when you rub a balloon across your hair or your socked feet across a carpet. You’re covering the balloon or yourself with negative particles. This imbalance of electrons is called static electricity.Eventually, you come into contact with something—another person or a metal doorknob, for instance—that is not electrically charged. The static “shock” you receive is the lightning-fast discharge of electrons.
Volcanic lightning is most often reported at night. Why do you think people are more likely to report seeing volcanic lightning at night than during the day?
Lightning from thunderclouds can appear as bolts, sheets, or balls. What shapes do you think volcanic lightning can take?
A common nickname for the conditions that support volcanic lightning is a “dirty thunderstorm.” What makes this thunderstorm “dirty”?
Term Part of Speech Definition Encyclopedic Entry ascend Verb
to go up.
layers of gases surrounding a planet or other celestial body.
Encyclopedic Entry: atmosphere charge separation Noun
building of space between charged particles. Sometimes called static electricity.
to press together in a smaller space.
tube or long, circular object.
having parts or molecules that are packed closely together.
to eject or get rid of.
to get rid of or throw out.
set of physical phenomena associated with the presence and flow of electric charge.
negatively charged subatomic particle.
to give off or send out.
to explode or suddenly eject material.
material that is able to flow and change shape.
force produced by rubbing one thing against another.
lava fountain Noun
phenomenon where lava is forcefully but not violently ejected from a volcano through a fissure or vent.
small piece of material.
study of the physical processes of the universe, especially the interaction of matter and energy.
static electricity Noun
motionless electronic charge that builds up on a material.
tectonic activity Noun
movement of tectonic plates resulting in geologic activity such as volcanic eruptions and earthquakes.
strong, destructive force.
volcanic ash Noun
fragments of lava less than 2 millimeters across.
Encyclopedic Entry: volcanic ash volcanic lightning Noun
bolts of electricity produced in a volcanic plume. Also called a dirty thunderstorm.
volcanic plume Noun
cylinder-shaped structure of volcanic ash and gas emitted by an explosive volcanic eruption. Also called an eruption column.
an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.
Encyclopedic Entry: volcano