Electrostatic forces alter particle size distributions in atmospheric dust

Abstract

Abstract. Large amounts of dust are lofted into the atmosphere from arid regions of the world before being transported up to thousands of kilometers. This atmospheric dust interacts with solar radiation and causes changes in the climate, with larger-sized particles having a heating effect, and smaller-sized particles having a cooling effect. Previous studies on the long-range transport of dust have found larger particles than expected, without a model to explain their transport. Here, we investigate the effect of electric fields on lofted airborne dust by blowing sand through a vertically oriented electric field, and characterizing the size distribution as a function of height. We also model this system, considering the gravitational, drag, and electrostatic forces on particles, to understand the effects of the electric field. Our results indicate that electric fields keep particles suspended at higher elevations and enrich the concentration of larger particles at higher elevations. We extend our model from the small-scale system to long-range atmospheric dust transport to develop insights into the effects of electric fields on size distributions of lofted dust in the atmosphere. We show that the presence of electric fields and the resulting electrostatic force on charged particles can help explain the transport of unexpectedly large particles and cause the size distribution to become more uniform as a function of elevation. Thus, our experimental and modeling results indicate that electrostatic forces may in some cases be relevant regarding the effect of atmospheric dust on the climate.

Surface charge of environmental and radioactive airborne particles

“…The surface charge densities reported here are reasonable since they are similar to results found in the literature. For example, the Arizona dust particles (mainly quartz) in this study had an average surface charge density of 1.12 ± 1.16 µC/m 2 , which is similar to the simulated value of 1.4 µC/m 2 for quartz particles with a diameter of 132 µm reported by Toth et al (2020). Additionally, Waitukaitis et al (2014) found that for quartz particles with a diameter ranging from 251 to 326 µm, the surface charge density was between 0.77 and 2.34 µC/m 2 .…”

Observed electric charge of insect swarms and their contribution to atmospheric electricity

“…For instance, entomogenic space charge is not considered in current climate models aimed at capturing the complex interplay between radiation and particulate matter, such as the atmospheric transport of dust. As atmospheric space charge enhances the aggregation and movement of aerial particles ( Toth et al., 2020 ), it is conceivable that insect-derived space charges will also contribute to spatial changes in aerial particles. For example, it could be speculated that insect-driven charged particle collection and transport could contribute to long-range transport of desert dust, providing alternative explanations for the transport of large particles, which cannot be explained by physical processes alone ( Toth et al., 2020 ; Does Van der et al, 2018 ).…”

“…As atmospheric space charge enhances the aggregation and movement of aerial particles ( Toth et al., 2020 ), it is conceivable that insect-derived space charges will also contribute to spatial changes in aerial particles. For example, it could be speculated that insect-driven charged particle collection and transport could contribute to long-range transport of desert dust, providing alternative explanations for the transport of large particles, which cannot be explained by physical processes alone ( Toth et al., 2020 ; Does Van der et al, 2018 ). Further, insects are not the only source of biogenic charge in the atmosphere, as birds and microorganisms also carry charge and abound in the lower atmosphere ( Badger et al., 2015 ; de Groot et al., 2021 ).…”

Lorentz Force Contribution to Thunderstorm's Electrical Characteristics

“…Electromagnetic forces could influence both generation (and maintenance) of the charged structure and the motion of tropical cyclones [29]. In reference [30], it is reported that the electrostatic forces could contribute to the warming of climate by increasing the concentration of large particles in atmospheric dust.…”