Abstract
Abstract. Agglomeration of charged ice and dust particles in the mesosphere and lower thermosphere is studied using a classical electrostatic approach, which is extended to capture the induced polarisation of surface charge. Collision outcomes are predicted whilst varying the particle size, charge, dielectric constant, relative kinetic energy, collision geometry and the coefficient of restitution. In addition to Coulomb forces acting on particles of opposite charge, instances of attraction between particles of the same sign of charge are discussed. These attractive forces are governed by the polarisation of surface charge and can be strong at very small separation distances. In the mesosphere and lower thermosphere, these interactions could also contribute to the formation of stable aggregates and contamination of ice particles through collisions with meteoric smoke particles.
Highlights
A significant fraction of the cosmic dust and meteoroid material that hits the Earth remains in the atmosphere for extended periods of time and is a source of solid dust particles, denoted as meteoric smoke particles (MSPs) (Megner et al, 2006; Rapp et al, 2012)
Agglomeration of charged ice and dust particles in the mesosphere and lower thermosphere is studied using a classical electrostatic approach, which is extended to capture the induced polarisation of surface charge
In the mesosphere and lower thermosphere, these interactions could contribute to the formation of stable aggregates and contamination of ice particles through collisions with meteoric smoke particles
Summary
A significant fraction of the cosmic dust and meteoroid material that hits the Earth remains in the atmosphere for extended periods of time and is a source of solid dust particles, denoted as meteoric smoke particles (MSPs) (Megner et al, 2006; Rapp et al, 2012). The model has successfully explained the effects of like-charge attraction in a range of coalescence processes such as the agglomeration of single particles and small clusters derived from a metal oxide composite (Lindgren et al, 2018b), aerosol growth in the atmosphere of Titan (Lindgren et al, 2017) and the self-assembly behaviour of charged micro-colloids (Naderi Mehr et al, 2020). To simulate the growth of ice onto the meteoric smoke, we examine the interactions between metal oxide particulates and large ice particles ranging in size from 10 to 100 nm and with charges 0 to −5e As these particles typically possess a low charge (or single charge arising, for example, from either a photoionisation event that removes a single electron from a molecule on the particle or the attachment of an ambient air ion) the charge distribution is best represented by a point free charge residing on the surface.
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