Is Near-Spherical Shape “the New Black” for Smoke ?

Abstract

<jats:p>We present smoke lidar measurements from the Canadian fires of 2017. The advected smoke layers over Europe are detected at both tropospheric and stratospheric heights, with the latter presenting non-typical values of the Particle Linear Depolarization Ratio (PLDR) with strong wavelength dependence from the UV to the Near-IR. Specifically, the PLDR values are of the order of 22, 18 and 4% at 355, 532 and 1064 nm respectively. In an attempt to interpret these results, we apply the hypothesis that smoke particles have near-spherical shapes. Scattering calculations with the T-matrix code support other findings in the literature ([1]- [2]), showing that the near-spherical shape (or closely similar shapes as in [2]), is the only shape that has been shown to reproduce the observed PLDR and Lidar Ratio (LR) values of the stratospheric smoke particles at the three measurement wavelengths.</jats:p>

Is the near-spherical shape the new black for smoke?

“…lidar measurements in Central (Ansmann et al, 2018;Q. Hu et al, 2019) and South Europe (Gialitaki et al, 2019;Sicard et al, 2019) revealed high PLDR values at 355 and 532 nm and a strong spectral dependence from the UV to the Near-IR.…”

Diffusion-limited aggregation

“…Once there, the new particle is let loose from infinity and joined to the expanding cluster. The model was investigated both on and off the lattice in multiple dimensions d 2; DLA has garnered a lot of attention throughout the years as a stunning illustration of fractal objects [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].This is a research report on diffusion-limited Aggregation. Diffusion-limited aggregation is a process in which particles of matter stick together (aggregate) as they chaotically move (diffuse) through a medium that provides some sort of resistive (limiting) force.…”

“…"Diffusion" refers to the random movement of the particles that make up the structure before they adhere ("Aggregate") to it. "Diffusion-limited" refers to the fact that the structure grows one particle at a time rather than in chunks of particles because the particles are thought to be in low concentrations, preventing them from coming into touch with one another [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Other instances include the development of coral, the route of lightning, the coalescence of dust or smoke particles, and the development of certain crystals.…”