When the right conditions combine all at once, huge electric currents can be found in the ash plumes of a volcanic eruption. The discharges create the unique and breathtaking phenomenon of volcanic lightning. Image credit: Ivan Alvarado / Reuters.

How do volcanoes make lightning?

The science of volcanic lighting is almost as spectacular as the phenomenon itself.

When hot, molten rock pushes its way up through the Earth’s crust and exits through to the surface, it often results in a volcanic eruption. These eruptions sometimes occur via slow and steady flows, but often show themselves in huge bursts of activity. When this latter case happens, a large amount of ash, dust, rock, volatile gases, and lava all are expelled in a very short period of time. While we might think of these as the major features of a volcano, there’s often a magnificent visual sight that accompanies these: volcanic lightning. Although not every eruption will produce this stunning light show, it’s been observed and recorded by humans for countless generations. Now, with our advanced understanding of physics and the physical sciences, we finally understand how it’s produced.

In 2015, the Chilean volcano Calbuco erupted for the first time in 42 years. Although the sight of volcanic lightning may be beautiful, the eruption itself causes significant damage and widespread devastation. Image credit: Jose Mancilla/LatinContent/Getty Images.

Magma, the subterranean predecessor to lava, can form in a variety of ways. Pockets of magma exist deep within the Earth’s mantle, originating as deep as the Earth’s liquid outer core, but are also created from the crust sliding over the top of the mantle. Either way, when…