In-cloud motions shape warm-rain production in marine clouds: Evidence from multiyear observations
4 affiliations
- 1Environmental Science and Technologies Department, Brookhaven National Laboratory, Upton, NY 11973
- 2School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794
- 3Department of Atmospheric and Oceanic Sciences, McGill University, Montréal, QC H3A 0G4, Canada
- 4Department of Environment, Land and Infrastructure Engineering (DIATI), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
Abstract
Despite years of research, the processes controlling warm-rain formation remain uncertain. Leveraging multiple years of observations collected across four oceanic regions, we systematically reassess the properties of precipitation just beneath cloud base. The observations show that warm-rain characteristics are remarkably consistent within cloud regimes yet differ substantially between stratocumulus and cumulus, indicating that cloud-regime properties exert a stronger influence on warm precipitation than regional environmental variability. Precipitation is observed beneath marine stratocumulus in over 56% of cloudy columns with liquid water path (LWP) <130 g m−2, rising to more than 84% in columns with LWP beyond 130 g m−2. This indicates that marine stratocumulus routinely support warm-rain formation and suggests that barriers to precipitation onset in this regime are weaker than commonly assumed. For the same LWP, oceanic cumulus precipitate less frequently than stratocumulus but on average produce two times larger and one to two orders of magnitude fewer precipitation drops. This contrast is consistent with cumulus presenting two times stronger updrafts and lower adiabaticity than stratocumulus, both of which can affect drop growth histories. Whereas the precipitation characteristics of stratocumulus are generally consistent with growth by collision–coalescence during gravitational free fall in low LWP clouds, those of cumulus cannot be explained without invoking additional processes. Together, these findings suggest that warm-precipitation parameterizations should more explicitly account for the influence of small-scale dynamical processes on precipitation growth. The apparent importance of drop growth histories further motivates continued exploration of Lagrangian particle-tracking approaches in both models and observations.
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BibTeX
@article{lamer2026incloud,
title = {{In-cloud motions shape warm-rain production in marine clouds: Evidence from multiyear observations}},
author = {Katia Lamer and Pavlos Kollias and Jiseob Kim and Zeen Zhu and Fan Yang and Alessandro Battaglia and Edward Luke},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
year = {2026},
month = oct,
doi = {10.1073/pnas.2608656123},
url = {https://doi.org/10.1073/pnas.2608656123},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - In-cloud motions shape warm-rain production in marine clouds: Evidence from multiyear observations
AU - Katia Lamer
AU - Pavlos Kollias
AU - Jiseob Kim
AU - Zeen Zhu
AU - Fan Yang
AU - Alessandro Battaglia
AU - Edward Luke
PY - 2026
DA - 2026/10/21
JO - Proceedings of the National Academy of Sciences of the United States of America
DO - 10.1073/pnas.2608656123
UR - https://doi.org/10.1073/pnas.2608656123
AB - Despite years of research, the processes controlling warm-rain formation remain uncertain. Leveraging multiple years of observations collected across four oceanic regions, we systematically reassess the properties of precipitation just beneath cloud base. The observations show that warm-rain characteristics are remarkably consistent within cloud regimes yet differ substantially between stratocumulus and cumulus, indicating that cloud-regime properties exert a stronger influence on warm precipitation than regional environmental variability. Precipitation is observed beneath marine stratocumulus in over 56% of cloudy columns with liquid water path (LWP) <130 g m−2, rising to more than 84% in columns with LWP beyond 130 g m−2. This indicates that marine stratocumulus routinely support warm-rain formation and suggests that barriers to precipitation onset in this regime are weaker than commonly assumed. For the same LWP, oceanic cumulus precipitate less frequently than stratocumulus but on average produce two times larger and one to two orders of magnitude fewer precipitation drops. This contrast is consistent with cumulus presenting two times stronger updrafts and lower adiabaticity than stratocumulus, both of which can affect drop growth histories. Whereas the precipitation characteristics of stratocumulus are generally consistent with growth by collision–coalescence during gravitational free fall in low LWP clouds, those of cumulus cannot be explained without invoking additional processes. Together, these findings suggest that warm-precipitation parameterizations should more explicitly account for the influence of small-scale dynamical processes on precipitation growth. The apparent importance of drop growth histories further motivates continued exploration of Lagrangian particle-tracking approaches in both models and observations.
SN - 0027-8424
SN - 1091-6490
ER -