The Rankine–Kirchhoff approximations for moist thermodynamics

Romps, David M.

doi:10.1002/qj.4154

Cited by 7 publications

(7 citation statements)

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“…However, this scenario is unlikely given that smaller liquid droplets tend to freeze at colder temperatures than large droplets (e.g., Bigg, 1955;Coopman et al, 2020), implying that polluted clouds may freeze their liquid water at a slower rate than their clean counterparts. We have not addressed warm-phase invigoration here, which may partially offset the cold-phase weakening effects we have described here (though this affect is likely small; e.g., Grabowski & Morrison, 2020, 2021Romps et al, 2023). We have also not considered longer timescale aerosol-cloud-environment feedbacks.…”

Section: Discussionmentioning

confidence: 97%

“…Our theoretical analysis uses the temperature and total water lapse rate equations derived in Peters et al (2022) (hereafter P22). The derivation of those equations uses the Rankine-Kirchoff approximations (Romps, 2021) and incorporates temperature-dependent latent heats of vaporization and freezing following Kirchoff's equations, accounts for the moisture dependency of the heat capacity, and includes open system effects, such as entrainment and precipitation. The most relevant assumptions in these equations to our forthcoming analysis are as follows:…”

Section: Analysis Methodsmentioning

confidence: 99%

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Entrainment Makes Pollution More Likely to Weaken Deep Convective Updrafts Than Invigorate Them

peters

Lebo

Chavas

et al. 2023

Geophysical Research Letters

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Are the results of aerosol invigoration studies that neglect entrainment valid for diluted deep convective clouds? We address this question by applying an entraining parcel model to soundings from tropical and midlatitude convective environments, wherein pollution is assumed to increase parcel condensate retention. Invigoration of 5%–10% and <2% is possible in undiluted tropical and midlatitude parcels respectively when freezing is rapid. This occurs because the positive buoyancy contribution from freezing is larger than the negative buoyancy contribution from condensate loading, leading to positive net condensate contribution to buoyancy. However, aerosol‐induced weakening is more likely when realistic entrainment rates occur because water losses from entrainment more substantially reduce the latent heating relative to the loading contribution. This leads to larger net negative buoyancy contribution from condensates in polluted than in clean entraining parcels. Our results demonstrate that accounting for entrainment is critical in conceptual models of aerosol indirect effects in deep convection.

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Section: Discussionmentioning

confidence: 97%

Section: Analysis Methodsmentioning

confidence: 99%

Entrainment Makes Pollution More Likely to Weaken Deep Convective Updrafts Than Invigorate Them

peters

Lebo

Chavas

et al. 2023

Geophysical Research Letters

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“…The thermodynamics of moist air in DAM is based on a standard set of approximations applying to mixtures of dry air and a condensible component, which may be present in vapor, liquid, and solid form. These approximations are (i) both dry air and the condensible vapor are treated as ideal gases, (ii) the heat capacities of all components are assumed not to depend on temperature, and (iii) condensates are assumed to have zero specific volume (Romps 2008;Ambaum 2010;Romps 2021).…”

Section: Thermodynamicsmentioning

confidence: 99%

Moist Convection Is Most Vigorous at Intermediate Atmospheric Humidity

Seeley

Wordsworth

2023

Planet. Sci. J.

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In Earth’s current climate, moist convective updraft speeds increase with surface warming. This trend suggests that very vigorous convection might be the norm in extremely hot and humid atmospheres, such as those undergoing a runaway greenhouse transition. However, theoretical and numerical evidence suggests that convection is actually gentle in water-vapor-dominated atmospheres, implying that convective vigor may peak at some intermediate humidity level. Here, we perform small-domain convection-resolving simulations of an Earth-like atmosphere over a wide range of surface temperatures and confirm that there is indeed a peak in convective vigor, which we show occurs near T s ≃ 330 K. We show that a similar peak in convective vigor exists when the relative abundance of water vapor is changed by varying the amount of background (noncondensing) gas at fixed T s , which may have implications for Earth’s climate and atmospheric chemistry during the Hadean and Archean eons. We also show that Titan-like thermodynamics (i.e., a thick nitrogen atmosphere with condensing methane and low gravity) produce a peak in convective vigor at T s ≃ 95 K, which is curiously close to the current surface temperature of Titan. Plotted as functions of the saturation-specific humidity at cloud base, metrics of convective vigor from both Earth-like and Titan-like experiments all peak when cloud-base air contains roughly 10% of the condensible gas by mass. Our results point to a potentially common phenomenon in terrestrial atmospheres: that moist convection is most vigorous when the condensible component is between dilute and nondilute abundance.

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“…Body temperature has important effects on the rates of enzymatic processes as well as the structural integrity of cellular membranes and proteins (Angilletta 2009), while all cellular processes rely on water as a solvent for biochemical reactions and for trafficking nutrients into, within, and out of cells (Chown & Nicolson 2004;Chaplin 2006). Temperature also affects the amount of desiccation stress an organism experiences due to the fundamental relationship between ambient temperature and the amount of water the surrounding air can hold (Lawrence 2005;Romps 2021). Other fields at the climate-health interface have explored the effects of wet heat vs dry heat on the energy budgets of endotherms in the context of human heat stress and climate change (Buzan & Huber 2020).…”

Section: Introductionmentioning

confidence: 99%

Humidity - The Overlooked Variable in Thermal Biology of Mosquito-Borne Disease

Brown

Pascual

Wimberly

et al. 2023

Preprint

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Vector-borne diseases cause significant financial and human loss, with billions of dollars spent on control. Arthropod vectors experience a complex suite of environmental factors that affect fitness, population growth, and species interactions across multiple spatial and temporal scales. Temperature and water availability are two of the most important abiotic variables influencing their distributions and abundances. While extensive research on temperature exists, the influence of humidity on vector and pathogen parameters affecting disease dynamics are less understood. Humidity is often underemphasized, and when considered, is often treated as independent of temperature even though desiccation likely contributes to declines in trait performance at warmer temperatures. This Perspectives explores how humidity shapes the thermal performance of mosquito-borne pathogen transmission. We summarize what is known about its effects and propose a conceptual model for how temperature and humidity interact to shape the range of temperatures across which mosquitoes persist and achieve high transmission potential. We discuss how failing to account for these interactions hinders efforts to forecast transmission dynamics and respond to epidemics of mosquito-borne infections. We outline future research areas that will ground the effects of humidity on the thermal biology of pathogen transmission in a theoretical and empirical framework to improve spatial and temporal prediction of vector-borne pathogen transmission.

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The Rankine–Kirchhoff approximations for moist thermodynamics

Cited by 7 publications

References 63 publications

Entrainment Makes Pollution More Likely to Weaken Deep Convective Updrafts Than Invigorate Them

Entrainment Makes Pollution More Likely to Weaken Deep Convective Updrafts Than Invigorate Them

Moist Convection Is Most Vigorous at Intermediate Atmospheric Humidity

Humidity - The Overlooked Variable in Thermal Biology of Mosquito-Borne Disease

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