Volcanic lightning can be partially powered by the natural radioactivity of the Earth | Science

Much of the lightning that flickers around and inside the plumes of ash from erupting volcanoes is triggered by static electricity, which accumulates when particles of ash rub against each other. the others in flight. A field study now suggests that the Earth's natural radioactivity could also help volcanic plumes recharge electrically, even when these clouds contain little or no ash.

Scientists have long known that radon, a radioactive gas, is one of the plumes that flow from active volcanoes. When these radioactive atoms disintegrate, they emit charged particles and create "daughter" elements that disintegrate and also emit charged particles. In the autumn of 2017, with the help of balloon-mounted instruments (pictured above) located at the top of Stromboli, an active volcano on an island near the Italian 'boot', researchers measured the amount of electrical charge accumulated in a rash plume the first time.

In some parts of the eruption cloud, the number of charged particles per cubic meter was at least 80 times greater than the number found in a typical cloud on a cloudy day. Geophysical Research Letters. The data also reveal that positive and negative charges migrate to different parts of the eruption plume, which creates voltage differences. The researchers noted that these differences are not strong enough to trigger lightning, but in plumes filled with ash, they can slightly increase or decrease the charge differences generated by static electricity. It is not yet well understood, they add, how such changes would affect the strength, frequency or brightness of volcanic lightning.