According to the Discovery Channel website, how volcanic lightning is formed has baffled scientists, who have been trying to unravel the mystery for years. Now, two research reports published in Geophysical Research Letters help explain this phenomenon and unify two conflicting views.
The formation of lightning is well understood: particles in clouds are charged, creating an electric field that separates positive and negative charges, and the occurrence of lightning keeps the electric field balanced. In thunderstorms, ice crystals are charged particles, but it's not clear whether volcanic lightning also requires ice crystals, or if friction between dust particles has a similar effect. Two recent studies suggest that both scenarios are true. Depends on the actual situation.
In the first study, Alexa Van Eaton, a volcanologist at the USGS Cascades Volcano Observatory, and colleagues used a network of lightning sensors to analyze the weather in April 2015. Lightning at the Calbuco volcano in Chile, they found that downwind of the volcano, lightning moved along dust plumes higher up, where temperatures were low enough to form ice crystal structures.
Alexa said: "The phenomenon of volcanic lightning is basically decoupled from all other dust particles falling on the ground, and instead seems to follow the ice crystals and remains higher in the atmosphere." Volcanic Lightning Is this how the mystery is revealed? Are ice crystals all necessary for volcanic lightning to form? Alexa and her colleagues found that lightning also occurs during the second phase of an eruption, when streams of dust and air are close to the Earth and away from any ice crystals, suggesting that collisions of dust particles can generate enough electrical charge.
A second study by Corrado Cimarelli, a volcanologist at the University of Munich in Germany, strengthens this theory by documenting the high speed of lightning at Sakurajima volcano on the Japanese island of Kyushu. Video, The volcano continued to erupt in 2009. Because the dust plume obscured the lightning that formed inside, Cimarelli and the research team also used proximity acoustic sensors and electromagnetic field measurements.
They found that in volcanic eruptions, volcanic ash and debris particles are close to each other, forming an electric charge. Cimarelli said: "When the Earth's atmosphere violently ejects dust, there will be a discharge here, independent of the level of the ejection." Van Eaten emphasized that we can definitely say that the volcanic plume is electrified in a short period of time, but in a The electrical changes in larger volcanic eruptions are often enhanced by the formation of ice crystals.
Van Eaten pointed out that this research will help us better achieve early warning of volcanic eruptions, especially remote volcanoes, and at the same time provide early warning and protection for air routes.