INSs can be divided into organic and inorganic substances. Inorganic INSs include mineral dusts, volcanic ash, metals, and metal oxides, with mineral dust being a particularly prevalent class of inorganic INSs in the atmosphere . Organic INSs include a wide range of materials such as bacterial cells, fungal and pollen spores, cell-free biomolecules such as proteins or polysaccharides, humic-like substances, secondary organic aerosols, and biomass burning aerosols . The properties of both organic and inorganic INSs have been studied in the laboratory, but the absolute and relative amount of organic and inorganic INSs in the atmosphere remains poorly constrained, leading to uncertainties when predicting mixed-phase and ice clouds in the atmosphere. .