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Abstract

Atmospheric ice-nucleating particles (INP) play an essential role in determining the optical thickness, lifetime, and phase of clouds (mixed-phase and cirrus clouds) [P. J. DeMott et al., 2010]. These characteristics of clouds, in turn, impact the Earth’s radiative budget. Despite significant advancements in the fundamental understanding of different ice formation processes in the last decades, the ice phase in clouds still contributes to substantial uncertainty in climate model predictions of the radiative forcing [Paul J. DeMott et al., 2011]. This presentation introduces the newly developed portable McGill Real-time Ice Nucleation Chamber (MRINC) for studying ice nucleation processes of nano to micron-sized particles in situ in real-time. The MRINC allows measuring INP concentrations under conditions pertinent to mixed-phase cloud temperatures from about −10 °C to about −38 °C. The MRINC is coupled with aerosol sizers (6 nm to 10 µm) and a Nano-Digital In-line Holographic Microscope (Nano-DIHM) to record the size distribution, phase, and shape of INPs. The characterization includes determining aerosol particles' size, shape, morphology, phase, and surface properties. We have shown preliminary results as proof of concept, where Nano-DIHM coupled with MRINC successfully distinguished silver iodide nucleated ice crystals and supercooled droplets in real time. We also provide an example of real-time capturing of the growth of sodium chloride (NaCl) and ammonium sulphate ((NH4)2SO4) aerosol particles in controlled temperature and humidity conditions using MRINC. We demonstrate that MRINC could be used for cloud condensation and ice nucleation studies.