2023 APS March Meeting
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session A16: From Grains to Complex Flows to Sustainable Materials: Soft Matter Meets Climate Change
8:00 AM–11:00 AM,
Monday, March 6, 2023
Room: Room 208
Sponsoring
Units:
DSOFT GSNP
Chair: Vinutha H.A., Georgetown University
Abstract: A16.00001 : Electrifying granular flows: probing the interior dynamics of volcanic plumes and pyrocumulonimbus clouds using electrostatics
8:00 AM–8:36 AM
Abstract
Presenter:
Joshua Mendez Harper
(University of Oregon)
Author:
Joshua Mendez Harper
(University of Oregon)
The electrification of volcanic plumes and wildfire-driven thunderstorms has been described intermittently for centuries, if not longer. For instance, Pliny the Younger noted dazzling lightning displays during the 79 AD eruption of Vesuvius. Although sometimes dismissed as secondary effects, recent work suggests that the electrical properties of ash and smoke clouds may reveal intrinsic properties of a flow that would otherwise be opaque to observation. Evidence for this hypothesis has steadily accumulated in the context of volcanic eruptions. Over the last decade, field studies across the world have shown that electrification in ash-laden plumes is ubiquitous. Paired with numerical models and focused laboratory experiments, these observations describe the microphysical mechanisms which link charge generation and electrical activity to the physical, chemical, and dynamic processes underpinning an eruption itself. Because lightning and associated electric fields may be measured remotely, understanding these relationships offers new opportunities to detect and monitor eruptions from afar, while safeguarding vulnerable populations. Recently, there has been substantial interest in applying these same principles to smoke plumes associated with mega-fires. The risk of devastating wildfires has increased in both historically-prone regions and areas where blazes were rare. Violent pyroconvection may generate wildfire-augmented thunderstorms, or pyrocumulonimbus clouds (pyroCb). These electrified storms act as "smoke stacks," efficiently transporting enormous amounts of particles from the surface to the lower stratosphere. More locally, pyroCbs may modify the course of a wildfire by increasing rate of fuel consumption, enhancing downwind ignition by wind-blown embers, and generating pyrogenic lightning. Like volcanic plumes, the internal dynamics and structure of pyroCbs are only marginally understood and the study of pyrogenic lightning is in its infancy. Monitoring extreme granular flows with electrostatic sensors requires an interdisciplinary approach at the intersection of soft matter, atmospheric science, electrostatics, and engineering. This talk summarizes the rapid and exciting progress toward this goal and provides a vision for future developments.