Preprints
https://doi.org/10.5194/egusphere-2024-3917
https://doi.org/10.5194/egusphere-2024-3917
19 Dec 2024
 | 19 Dec 2024

Retention During Freezing of Raindrops, Part I: Investigation of Single and Binary Mixtures

Martanda Gautam, Alexander Theis, Jackson Seymore, Moritz Hey, Stephan Borrmann, Karoline Diehl, Subir K. Mitra, and Miklós Szakáll

Abstract. The interaction with freezing processes and vertical transport of trace gases into the upper atmosphere during deep convection is critical to understanding the distribution of aerosol precursors and their climate effects. We conducted experimental studies inside a walk-in cold room for freely levitating rain drops (D = 2 mm) using an acoustic levitator apparatus. We investigated the effect of freezing raindrops on the retention of organic species for the first time with silver iodide as the ice nucleating agent. Quantitative chemical analysis determined the retention coefficient, which is defined as the fraction of a chemical species remaining in the ice phase compared to their initial liquid phase concentrations. We measured the retention coefficients of nitric acid, formic acid, acetic acid, and 2-nitrophenol as single components. Furthermore, we determined the retention coefficients of these substances as binary mixtures. Our results show the dominance of physical properties over their chemical counterparts on overall retention for the investigated large drops. Thus, for rain sized drops almost everything is fully retained during the freezing process, even for species with low effective Henry’s law constants. An ice shell is formed within 4.8 ms around the drops just after the freezing was initiated. This ice shell formation was found to be the controlling factor for the overall retention of the investigated species, which inhibited any further expulsion of dissolved substances from the drop.

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Journal article(s) based on this preprint

01 Oct 2025
Retention during freezing of raindrops – Part 1: Investigation of single and binary mixtures of nitric, formic, and acetic acids and 2-nitrophenol
Martanda Gautam, Alexander Theis, Jackson Seymore, Moritz Hey, Stephan Borrmann, Karoline Diehl, Subir K. Mitra, and Miklós Szakáll
Atmos. Chem. Phys., 25, 11813–11828, https://doi.org/10.5194/acp-25-11813-2025,https://doi.org/10.5194/acp-25-11813-2025, 2025
Short summary
Martanda Gautam, Alexander Theis, Jackson Seymore, Moritz Hey, Stephan Borrmann, Karoline Diehl, Subir K. Mitra, and Miklós Szakáll

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-3917', Anonymous Referee #1, 09 Jan 2025
  • RC2: 'Comment on egusphere-2024-3917', Gabor Vali, 12 Jan 2025
  • AC1: 'Comment on egusphere-2024-3917', Martanda Gautam, 13 Apr 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-3917', Anonymous Referee #1, 09 Jan 2025
  • RC2: 'Comment on egusphere-2024-3917', Gabor Vali, 12 Jan 2025
  • AC1: 'Comment on egusphere-2024-3917', Martanda Gautam, 13 Apr 2025

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Martanda Gautam on behalf of the Authors (13 Apr 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish subject to minor revisions (review by editor) (17 Apr 2025) by Barbara Ervens
AR by Martanda Gautam on behalf of the Authors (13 May 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (16 May 2025) by Barbara Ervens
AR by Martanda Gautam on behalf of the Authors (20 May 2025)  Manuscript 

Journal article(s) based on this preprint

01 Oct 2025
Retention during freezing of raindrops – Part 1: Investigation of single and binary mixtures of nitric, formic, and acetic acids and 2-nitrophenol
Martanda Gautam, Alexander Theis, Jackson Seymore, Moritz Hey, Stephan Borrmann, Karoline Diehl, Subir K. Mitra, and Miklós Szakáll
Atmos. Chem. Phys., 25, 11813–11828, https://doi.org/10.5194/acp-25-11813-2025,https://doi.org/10.5194/acp-25-11813-2025, 2025
Short summary
Martanda Gautam, Alexander Theis, Jackson Seymore, Moritz Hey, Stephan Borrmann, Karoline Diehl, Subir K. Mitra, and Miklós Szakáll

Data sets

Retention During Freezing of Raindrops, Part I: Investigation of Single and Binary Mixtures Martanda Gautam, Alexander Theis, Jackson Seymore, Moritz Hey, Subir K. Mitra, and Miklós Szakáll https://doi.org/10.5281/zenodo.14319647

Martanda Gautam, Alexander Theis, Jackson Seymore, Moritz Hey, Stephan Borrmann, Karoline Diehl, Subir K. Mitra, and Miklós Szakáll

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Short summary
We investigated the retention of chemical species and their binary mixtures during freezing of raindrops via acoustic levitation. Our results reveal high retention-nearly all substances being fully retained during freezing. This could be attributed to faster freezing time compared to slower mass expulsion time, along with ice-shell formation during freezing. This result helps improve our understanding of interaction between ice microphysical processes and chemistry in deep convective clouds.
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