Effects of solid aerosols on partially glaciated clouds

Kudzotsa, Innocent; Phillips, Vaughan T. J.; Dobbie, S.

doi:10.1002/qj.3376

Cited by 4 publications

(3 citation statements)

References 72 publications

(186 reference statements)

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“…Ice nucleating particles (INPs) can initiate heterogeneous nucleation of ice within cloud droplets at temperatures warmer than those required for homogeneous nucleation. As a result, INPs can influence the radiative properties and lifetime of clouds, as well as climate and the hydrological cycle. − The modes of heterogeneous nucleation include deposition nucleation, pore-condensation freezing, contact freezing, and immersion freezing. , The immersion freezing mode refers to the freezing initiated by INPs immersed in liquid droplets. This mode is the most relevant for ice formation in mixed-phase clouds , and is the focus of this study.…”

Section: Introductionmentioning

confidence: 99%

Effects of Inorganic Acids and Organic Solutes on the Ice Nucleating Ability and Surface Properties of Potassium-Rich Feldspar

Yun

Kumar

Removski

et al. 2021

ACS Earth Space Chem.

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Mineral dust particles can initiate the freezing of cloud droplets in the atmosphere. The freezing efficiency of these particles can, however, be strongly affected by solutes, such as inorganic acids, polyols, and carboxylic acids. Here, we report the effects of inorganic acids (HNO 3 and HCl), polyols, and carboxylic acids at low concentrations on the ice nucleating ability of potassium-rich feldspar (K-rich feldspar) using the droplet freezing technique. The inorganic acids and carboxylic acids decreased the median freezing temperature of droplets containing K-rich feldspar by up to 7 °C, while the polyols had no significant effect on the median freezing temperature. For the inorganic acids and carboxylic acids, the median freezing temperature was a strong function of the pH of the droplets, with the median freezing temperature decreasing as the pH decreased. By examining the surface properties of K-rich feldspar exposed to different concentrations of HCl with cryogenic X-ray photoelectron spectroscopy, we show that the decrease in the ice nucleating ability of Krich feldspar by the inorganic acids and carboxylic acids was likely caused by ion exchange (H 3 O + with parent K + in microcline) and the incongruent dissolution of Al with respect to Si at K-rich feldspar surfaces. The decrease in the ice nucleating ability of K-rich feldspar by the carboxylic acids only related to the pH of the droplets rather than the type of carboxylic acid and their expected binding mechanisms on K-rich feldspar. This study focuses on rare ice nucleating active sites (with an ice nucleating active site density of 10−600 cm −2 ) of the K-rich feldspar and short exposure times between the solutes and the K-rich feldspar. Further studies are needed to investigate more abundant ice nucleating active sites and longer exposure times, as well as K-rich feldspar samples from different sources.

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Section: Introductionmentioning

confidence: 99%

Effects of Inorganic Acids and Organic Solutes on the Ice Nucleating Ability and Surface Properties of Potassium-Rich Feldspar

Yun

Kumar

Removski

et al. 2021

ACS Earth Space Chem.

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“…The formation of ice in clouds can strongly influence their lifetime and optical properties. − Ice forms in clouds by either homogeneous freezing or heterogeneous freezing initiated by a foreign nucleus, also called an ice nucleating particle (INP). Heterogeneous freezing can be classified as deposition freezing, immersion freezing, condensation freezing, contact freezing, or pore condensation freezing. , In this paper, we focus on immersion freezing, which refers to ice nucleation initiated by an INP immersed in a liquid droplet.…”

Section: Introductionmentioning

confidence: 99%

Surface Composition Dependence on the Ice Nucleating Ability of Potassium-Rich Feldspar

Yun

Link

Kumar

et al. 2020

ACS Earth Space Chem.

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Mineral dust particles are one of the most abundant types of ice nucleating particles in the atmosphere. During atmospheric transport, these particles can be coated with water-soluble solutes, which can modify their ice nucleating ability. Although previous studies have shown that even low concentrations of water-soluble solutes can modify the ice nucleating properties of mineral dust particles, our understanding of this topic is far from complete. We examined the effects of a series of alkali metal nitrates at low concentrations (5 × 10 −5 M to 5 × 10 −3 M) on the surface composition and immersion freezing of potassium-rich feldspar (K-rich feldspar). Immersion freezing was investigated with the droplet freezing technique, and the surface composition was investigated with cryogenic X-ray photoelectron spectroscopy. K + increased the median freezing temperature of the droplets, while the other alkali metal cations either had no effect or decreased the median freezing temperature. The changes in the median freezing temperature of the droplets due to the presence of nitrates followed the order K + ≥ Li + ≥ Na + ≥ Rb + ≥ Cs + and, except for Cs + , were correlated to the K/Al ratio at the surface of K-rich feldspar. The K/Al ratio is possibly an indicator of the abundance of certain types of K-bearing microcline surfaces that drive the immersion freezing of K-rich feldspar, while Cs + likely influences the immersion freezing of K-rich feldspar by an additional mechanism, possibly blocking ice nucleation sites by adsorption. Our work also shows that the cation charge density (charge density over the surface area of a single cation) is not a good predictor of the effects of cations on the immersion freezing of K-rich feldspar in our experiments.

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“…These particles can modify the properties of mixed-phase clouds, including their lifetime and optical properties, by changing the ratio of ice to liquid water in these clouds. [3][4][5][6][7][8] Hence, information on the concentrations, composition, and sources of INPs in the Arctic is critical to predict climate and the hydrological cycle in the region. Furthermore, as temperatures increase in the Arctic, 9,10 the coverage of sea ice and land snow is expected to decrease.…”

Section: Introductionmentioning

confidence: 99%