Microfluidic immersion freezing of binary mineral mixtures containing microcline, montmorillonite, or quartz


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Date

2025-12-09

Publication Type

Journal Article

ETH Bibliography

yes

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Abstract

Mineral dusts are among the most active ice-nucleating particles present in cloud droplets, with their properties influencing radiative properties and precipitation formation. To improve weather predictions and climate projections, it is important to understand under which conditions ice will form on mineral dusts. Laboratory experiments have primarily focused on single minerals, and field samples are complex mixtures that cannot be controlled in their composition or particle size. To fill this gap, a bottom-up investigation of suspensions containing pure or binary mixtures of microcline, montmorillonite, or quartz at concentrations between 0.0001 and 0.1 wt % is presented. Arrays of monodisperse aqueous droplets (diameters of 75 μm) are generated using a microfluidic device and subsequently cooled at a rate of 1 K min-1. The probability of freezing in the presence of binary mixtures generally follows that of the most ice-active mineral. Each pure mineral's nucleation site density is fit as a function of temperature and used to predict the frozen fraction curves for each binary mixture assuming additivity of mineral surface area. Predictions are also made for Arizona Test Dust from the obtained pure mineral fits, and general agreement with experiments is observed. This work presents a systematic study of ice formation in the presence of pure and binary mixtures of common mineral dusts, providing information for the future design of composition-aware parameterizations for ice nucleation in the atmosphere.

Publication status

published

Editor

Book title

Volume

25 (23)

Pages / Article No.

17997 - 18014

Publisher

Copernicus

Event

Edition / version

Methods

Software

Geographic location

Date collected

Date created

Subject

Organisational unit

03914 - deMello, Andrew / deMello, Andrew check_circle
03690 - Lohmann, Ulrike / Lohmann, Ulrike check_circle

Notes

Funding

20-1 FEL-46 - Ice nucleation in mineral dust mixtures: measurements, predictions, and implications for the climate (ETHZ)

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