Condensation–mass flux connection in warm convective clouds: theory and implications for cloud supersaturation DOI Creative Commons
Yefim L. Kogan

Advances in science and research, Journal Year: 2022, Volume and Issue: 19, P. 91 - 95

Published: Aug. 22, 2022

Abstract. The study focused on the relationship between Condensation Rate (CR) and upward/Plus Mass Flux (MFP) in a system of trade wind cumulus clouds simulated by an LES model. model was initialized with data observed during RICO field project, 50.0×50.0 km horizontal domain. In our previous (Kogan, 2021) we showed that nearly perfect correlation exists CR MFP (correlation coefficient R=0.99). As result, condensation rate can be highly accurately expressed as linear function upward mass flux. This derived finding explained using theory concept quasi-steady supersaturation. obtained from slope CR–MFP fit excellent agreement its theoretical value (error less than 5 %). also equality values follows supersaturation value. results suggest rates, for variety cloud conditions, precisely estimated single variable–upward Possible implications evaluating degree non-adiabaticity are discussed.

Language: Английский

The Rapid Transition From Shallow to Precipitating Convection as a Predator–Prey Process DOI Creative Commons
Cristian V. Vraciu, Julien Savre, Maxime Colin

et al.

Journal of Advances in Modeling Earth Systems, Journal Year: 2025, Volume and Issue: 17(2)

Published: Feb. 1, 2025

Abstract Properly predicting the rapid transition from shallow to precipitating atmospheric convection within a diurnal cycle over land is of great importance for both weather prediction and climate projections. In this work, we consider that cumulus cloud formed due transport water mass by multiple updrafts during its lifetime. Cumulus clouds then locally create favorable conditions subsequent convective reach higher altitudes, leading deeper convection. This mechanism amplified cold pools evaporation precipitation in sub‐cloud layer. Based on conceptual view cloud–cloud interactions which goes beyond one equals one–plume picture, it argued may act as predators prey total population, such shallow–to–deep can be modeled simple predator–prey system. model validated comparing solutions Lotka‐Volterra system equations results obtained using high‐resolution large‐eddy simulation model. Moreover, argue complete deep seen with varying food supply prey. Finally, suggest based present model, new unified cloud‐convection parameterizations designed lead improved representations continental

Language: Английский

Citations

0
The Role of the Toroidal Vortex in Cumulus Clouds' Entrainment and Mixing DOI Creative Commons
Eshkol Eytan, Y. Arieli, А. Хаин

et al.

Journal of Geophysical Research Atmospheres, Journal Year: 2024, Volume and Issue: 129(14)

Published: July 10, 2024

Abstract Shallow convective clouds play a crucial role in Earth's energy budget, as they modulate the radiative transfer atmosphere and participate vertical transport of aerosols, energy, humidity. The parameterizations representing these complex, vital players weather climate models are mostly based on description steady‐state plumes source major uncertainty. Recently, several studies have shown that buoyant thermals inherent atmospheric convection contain toroidal (ring) vortex. This work those vortices growing shallow cumulus (Cu) using high‐resolution (10 m) Large Eddy Simulations resolve much detail. Recent analysis such data showed small‐scale turbulent diffusion is unable to explain large diluted portion cloud. Here we advocate for important Cu vortex (TV) cloud dilution present complex dynamics structure TV. Nevertheless, since dominates cloud's dilution, simplicity emerges when considering lateral mass flux profile. mixing quantified direct calculations Eulerian tracers. In addition, Lagrangian tracers used identify origin entrained air its thermodynamic properties. It shows most by not recycled vortex, yet significantly more humid than environment. We suggest development new describing thermals, together with their vortices, might improve models.

Language: Английский

Citations

3
Cloud Microphysics Investigations with the Cloudkite Laboratory DOI Creative Commons
Marcel Schröder

Published: Jan. 1, 2023

Clouds are crucial to the Earth’s radiation budget and energy balance. Inadequately resolved cloud processes a major source of uncertainty in weather forecasts climate prediction. Due their turbulent nature, dynamics span vast range spatial temporal scales from μm km ms h, respectively. Together with phase transitions, transport heat moisture as well droplet-turbulence interaction, multiscale property turbulence poses huge challenge for unraveling processes. Deployed by kite-stabilized helium-filled aerostats, so-called helikites, two specially designed instruments, Max-Planck-Cloudkite + (MPCK+) mini-Max-Planck-Cloudkite (mini-MPCK), measure atmospheric state flow velocity microphysical properties. During EUREC4A field campaign Caribbean January February 2020 above Atlantic Ocean, both MPCK+ mini-MPCK profiled boundary layer trade-wind region sampled clouds. In this thesis, we report measurements dissipation rate droplet statistics region. The is one most fundamental characteristics estimated one-dimensional time-records. To benchmark different methods estimating rate, each method compared ground-truth reference direct numerical simulation (DNS) stationary homogeneous isotropic at Taylor-scale Reynolds numbers between 74 321. impact finite intensity misalignment probe orientation mean direction systematically studied expressed analytical expressions. Additionally, effect averaging window its Rλ dependence captured scaling arguments which hot-wire Max Planck Variable Density Turbulence Tunnel 147 5864. Both interaction investigated help estimates from, total, 197 h record scientific data. This thesis examines distribution droplets cumuli, onset warm-rain initiation altitude size distribution, analyzed based on 144 records. Furthermore, layer, stability isotropy inertial length determined.

Language: Английский

Citations

6
The rapid transition from shallow to precipitating convection as a predator-prey process DOI Open Access
Cristian V. Vraciu, Julien Savre, Maxime Colin

et al.

Authorea (Authorea), Journal Year: 2024, Volume and Issue: unknown

Published: March 5, 2024

Properly predicting the rapid transition from shallow to precipitating atmospheric convection within a diurnal cycle over land is of great importance for both weather prediction and climate projections. In this work, we consider that cumulus cloud formed due transport water mass by multiple updrafts during its life-time. Cumulus clouds then locally create favorable conditions subsequent convective reach higher altitudes, leading deeper convection. This mechanism amplified cold pools evaporation precipitation in sub-cloud layer. Based on conceptual view cloud-cloud interactions which goes beyond one equals one-plume picture, it argued may act as predators prey total population, such shallow-to-deep can be modeled simple predator-prey system. model validated comparing solutions Lotka-Volterra system equations results obtained using high-resolution large-eddy simulation model. Moreover, argue complete deep seen with varying food supply prey. Finally, suggest present applied models, lead improved representations continental

Language: Английский

Citations

1
Dynamics and microphysics in small developing cumulus clouds DOI
А. Хаин,

Mark Pinsky,

Eshkol Eytan

et al.

Atmospheric Research, Journal Year: 2024, Volume and Issue: 307, P. 107454 - 107454

Published: May 3, 2024

Language: Английский

Citations

1
Turbulence-induced droplet grouping and augmented rain formation in cumulus clouds DOI Creative Commons
Siddharth Gumber, Sudarsan Bera, S. Ghosh

et al.

Scientific Reports, Journal Year: 2024, Volume and Issue: 14(1)

Published: May 4, 2024

Abstract This paper provides the first observational analysis of how droplet separation is impacted by flinging action microscale vortices in turbulent clouds over a select radii range and they vary cloud cores along peripheral edges. It premised that this mechanism initiates within volume soon after condensational growth, largely core, operates until exceed 20–30 µm when effect fades rapidly. New observations are presented showing also impact settling rates droplets critical size (6–18 µm) causing them to sediment faster than still air affecting swept volumes thereby impacting rain initiation formation. Large-scale atmospheric models ignore these effects linked rapid growth during early stages conversion. Previous studies on spatial organization edges inside deep core have shown homogeneous Poisson statistics, indicative presence vigorous in-cloud mixing process at small scales obtained, contrast an inhomogeneous distribution In paper, it established marked region, homogeneity can be vortical activity which flings 6–18 outward. The typical radius trajectories or flung around correlates with interparticle distance strongly. correlation starts diminish as one proceeds from central fringes because added entrainment cloud-free air. These results imply augmented small-scale interaction prior other more large-scale processes involving mixing. study, combining amplified velocities included Weather Research Forecasting- LES case study. Not only significant differences observed morphology compared baseline case, but ‘enhanced’ shows commencement rainfall intense precipitation ‘standard’ case. modelled equilibrium raindrop spectrum agrees better enhanced sedimentation mediated calculations where still-air terminal used.

Language: Английский

Citations

1
The Impact of Temperature on the Adiabaticity and Coverage of a Single Shallow Cumulus Cloud DOI Creative Commons
Kang‐En Huang, Minghuai Wang, Daniel Rosenfeld

et al.

Journal of Geophysical Research Atmospheres, Journal Year: 2024, Volume and Issue: 129(22)

Published: Nov. 16, 2024

Abstract The uncertainty of climate projection is significantly related to warm cloud feedback, which involves a complex interplay various mechanisms. However, it hard unentangle temperature's impact on single with experiments, since the dynamics always covary environmental thermodynamical conditions. In this study, we investigate simulated shallow cumulus cloud's response temperature using two perturbation methods, namely “uniform” and “buoyancy‐fixed”, latter keeps buoyancy profile unchanged in perturbation. High‐resolution large eddy simulations show that uniform warming increases buoyancy, reducing adiabaticity. If fixed, only reduces area, leaving adiabatic fraction almost unchanged. Such can be explained by Clausius‐Clapeyron effect an idealized 1D diffusion model, showing cloud‐environment absolute humidity difference more than increase liquid water content, resulting faster loss both coverage total solely lateral mixing. responses counteract, making insensitive change. Our work shows fraction's sensitive perturbed structure boundary layer, reduction acts as positive feedback mechanism addition adjustment processes layer.

Language: Английский

Citations

1
Entrainment rates in the cloud zones of continental shallow cumulus DOI
Neelam Malap,

Thara V. Prabha

Atmospheric Research, Journal Year: 2023, Volume and Issue: 286, P. 106679 - 106679

Published: Feb. 26, 2023

Language: Английский

Citations

3
The Impact of Temperature on the Adiabaticity and Coverage of a Single Shallow Cumulus Cloud DOI Open Access
Kang‐En Huang, Minghuai Wang, Daniel Rosenfeld

et al.

Authorea (Authorea), Journal Year: 2024, Volume and Issue: unknown

Published: June 8, 2024

The uncertainty of climate projection is significantly contributed by warm cloud feedback, which involves a complex interplay various mechanisms. However, it hard to unentangle temperature’s impact on single with experiments, since the dynamics always covaries environmental thermodynamical conditions. In this study, we investigate simulated shallow cumulus cloud’s response temperature using two perturbation methods, namely “uniform” and “buoyancy-fixed”, latter keeps buoyancy profile unchanged in perturbation. High-resolution large eddy simulation shows that uniform warming increases buoyancy, reducing adiabaticity. If fixed, only reduces area, leaving adiabatic fraction almost unchanged. Such can be explained Clausius-Clapeyron effect an idealized 1D diffusion model, showing cloud-environment absolute humidity difference more than increase liquid water content, resulting faster loss both coverage total solely lateral mixing. responses counteract, making insensitive change. Our works fraction’s sensitive perturbed structure boundary layer, reduction acts as positive feedback mechanism addition adjustment processes layer.

Language: Английский

Citations

0
Condensation–mass flux connection in warm convective clouds: theory and implications for cloud supersaturation DOI Creative Commons
Yefim L. Kogan

Advances in science and research, Journal Year: 2022, Volume and Issue: 19, P. 91 - 95

Published: Aug. 22, 2022

Abstract. The study focused on the relationship between Condensation Rate (CR) and upward/Plus Mass Flux (MFP) in a system of trade wind cumulus clouds simulated by an LES model. model was initialized with data observed during RICO field project, 50.0×50.0 km horizontal domain. In our previous (Kogan, 2021) we showed that nearly perfect correlation exists CR MFP (correlation coefficient R=0.99). As result, condensation rate can be highly accurately expressed as linear function upward mass flux. This derived finding explained using theory concept quasi-steady supersaturation. obtained from slope CR–MFP fit excellent agreement its theoretical value (error less than 5 %). also equality values follows supersaturation value. results suggest rates, for variety cloud conditions, precisely estimated single variable–upward Possible implications evaluating degree non-adiabaticity are discussed.

Language: Английский

Citations

1