Subvisible/submicron particulate is commonly presents in environment. Particulate is classified in three modes namely ultrafine (nucleation and Aitken mode, diameter less than 0.1 μm), fine (mainly accumulation mode, aerodynamic diameter between 0 and 2.5 μm) and coarse (aerodynamic diameter between 2.5 and 10 μm). Generally, fine and ultrafine particles are formed from high temperature processes such as vehicular exhaust, oil and coal combustion, biomass burning, industrial processes, and chemical reactions in the atmosphere. Coarse particles are generally evolved from attrition processes including mechanical abrasion of crustal material and re-suspension of road and soil dusts, sea spray, volcanic eruptions and brake and tyre wear from vehicles.

The case of dust in glacial water

Dust influences global climate both directly, by changing the radiative properties of the atmosphere through scattering and absorption of solar (shortwave) and terrestrial (longwave) radiation, and indirectly, impacting on cloud formation and properties. While most modelling studies assume a spherical shape for dust particles, detailed analyses of modern desert dust reveal significant deviations of light scattering from scattering properties of homogeneous spheres. Accordingly, adequate modelling of light scattering by non-spherical particles is necessary but represents one of the major difficulties in remote sensing of modern aerosols and dust. CLASSIZER ONE measures directly the dust optical thickness (ρ) and the extinction cross section (Cext) for each measured particle. Thus, CLASSIZER ONE derives information on dust particle shapes (and aspect ratio in particular), which is a critical piece of information needed to properly derive the intrinsic optical properties used by radiative transfer models.