The impact of the sulfur allotropes and sulfur hydrides on the Venus cloud chemistry
Abstract
Venus is home to vivid sulfur chemistry, with SO2 as the major sulfur gas species and a global cloud layer between 47 and~70 km composed of H2SO4 and H2O. The chemistry in the clouds has been extensively studied with 1D models, but none is able to reproduce the three orders of magnitude decrease of SO2 inside the clouds. Sulfur allotrope chemistry could be a candidate for buffering sulfur atoms, as it can grow into long chains. Sulfur hydrides such as H2S is considered as one of the main sulfur-bearing compounds, possibly linked to surface reactions or have a volcanic origin like on Earth. In this study, we use for the first time a 3D model to study the climatology of the sulfur allotrope in gas and condensed phase and hydride chemistry in the clouds with an explicit photolysis calculation and updated UV cross-section. H2S is close to ppmv levels below the cloud base, the third most abundant sulfur-bearing species in this region after SO2 and OCS. Below the clouds, S8 gas phase is the most abundant sulfur allotrope. Above, the photolysis and condensation are preponderant, and the gas phase decreases to extremely low values. Polysulfur can therefore not be the unknown absorber at cloud-top altitudes. The condensed phase polysulfurs are present from 30 to above 100~km. S2 condensed phase is the most abundant due to its low saturation mixing ratios. Polysulfur species represent a substantial sulfur reservoir in the upper cloud, equivalent to a few ppmv.
Versions
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BibTeX
@misc{lefevre2026impact,
title = {{The impact of the sulfur allotropes and sulfur hydrides on the Venus cloud chemistry}},
author = {Maxence Lefèvre and Franck Lefèvre and Anni Määttänen and Robert Skog and Benjamin Frandsen and Aurélien Stolzenbach and Ashwin Braude},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.36979},
eprint = {2610.36979},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.36979},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The impact of the sulfur allotropes and sulfur hydrides on the Venus cloud chemistry
AU - Maxence Lefèvre
AU - Franck Lefèvre
AU - Anni Määttänen
AU - Robert Skog
AU - Benjamin Frandsen
AU - Aurélien Stolzenbach
AU - Ashwin Braude
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.36979
UR - https://arxiv.org/abs/2610.36979
AB - Venus is home to vivid sulfur chemistry, with SO_2 as the major sulfur gas species and a global cloud layer between 47 and~70 km composed of H_2SO_4 and H_2O. The chemistry in the clouds has been extensively studied with 1D models, but none is able to reproduce the three orders of magnitude decrease of SO_2 inside the clouds. Sulfur allotrope chemistry could be a candidate for buffering sulfur atoms, as it can grow into long chains. Sulfur hydrides such as H_2S is considered as one of the main sulfur-bearing compounds, possibly linked to surface reactions or have a volcanic origin like on Earth. In this study, we use for the first time a 3D model to study the climatology of the sulfur allotrope in gas and condensed phase and hydride chemistry in the clouds with an explicit photolysis calculation and updated UV cross-section. H_2S is close to ppmv levels below the cloud base, the third most abundant sulfur-bearing species in this region after SO_2 and OCS. Below the clouds, S_8 gas phase is the most abundant sulfur allotrope. Above, the photolysis and condensation are preponderant, and the gas phase decreases to extremely low values. Polysulfur can therefore not be the unknown absorber at cloud-top altitudes. The condensed phase polysulfurs are present from 30 to above 100~km. S_2 condensed phase is the most abundant due to its low saturation mixing ratios. Polysulfur species represent a substantial sulfur reservoir in the upper cloud, equivalent to a few ppmv.
ER -