Olaf Hellmuth
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View article: Particle deliquescence in a turbulent humidity field
Particle deliquescence in a turbulent humidity field Open
The atmosphere contains aerosol particles, some of which are hygroscopic in nature. These particles have direct and indirect effects on weather and climate. Furthermore, turbulence causes fluctuations in temperature, water vapor content, a…
View article: Particle deliquescence in a turbulent humidity field
Particle deliquescence in a turbulent humidity field Open
The atmosphere contains aerosol particles, some of which are hygroscopic in nature. These particles have direct and indirect effects on weather and climate. Furthermore, turbulence causes fluctuations in temperature, water vapor content, a…
View article: Correction: Feistel, R.; Hellmuth, O. Irreversible Thermodynamics of Seawater Evaporation. J. Mar. Sci. Eng. 2024, 12, 166
Correction: Feistel, R.; Hellmuth, O. Irreversible Thermodynamics of Seawater Evaporation. J. Mar. Sci. Eng. 2024, 12, 166 Open
A sign error has been found in Equation (32) of the paper [...]JW=−Dfln1+SMW1−SMS+lnψfxV,T,p[...]
View article: TEOS-10 Equations for Determining the Lifted Condensation Level (LCL) and Climatic Feedback of Marine Clouds
TEOS-10 Equations for Determining the Lifted Condensation Level (LCL) and Climatic Feedback of Marine Clouds Open
At an energy flux imbalance of about 1 W m−2, the ocean stores 90% of the heat accumulating by global warming. However, neither the causes of this nor the responsible geophysical processes are sufficiently well understood. More detailed in…
View article: TEOS-10 Equations for the Lifted Condensation Level (LCL) and Climatic Feedback of Marine Clouds
TEOS-10 Equations for the Lifted Condensation Level (LCL) and Climatic Feedback of Marine Clouds Open
At an energy flux imbalance of about 1 W m–2, the ocean is storing 90 % of the heat accumulating by global warming. However, neither the causes nor the responsible geophysical processes are sufficiently well understood. More detailed inves…
View article: Irreversible Thermodynamics of Seawater Evaporation
Irreversible Thermodynamics of Seawater Evaporation Open
Under typical marine conditions of about 80% relative humidity, evaporation of water from the ocean is an irreversible process accompanied by entropy production. In this article, equations are derived for the latent heat of irreversible ev…
View article: The role of a low-level jet for stirring the stable atmospheric surface layer in the Arctic
The role of a low-level jet for stirring the stable atmospheric surface layer in the Arctic Open
In this study, we analyze the transition of a stable atmospheric boundary layer (ABL) with a low-level jet (LLJ) to a traditional stable ABL with a classic Ekman helix in the late-winter central Arctic. Vertical profiles in the ABL were me…
View article: Irreversible Thermodynamics of Seawater Evaporation
Irreversible Thermodynamics of Seawater Evaporation Open
Under typical marine conditions of about 80 % relative humidity, evaporation of water from the ocean is an irreversible process accompanied by entropy production. In this article, equations are derived for the latent heat of irreversible e…
View article: Comment on egusphere-2023-567
Comment on egusphere-2023-567 Open
Abstract. In this study, we analyze the transition of a stable atmospheric boundary layer (ABL) with a low-level jet (LLJ) to a traditional stable ABL with a classic Ekman helix in the late-winter central Arctic. Vertical profiles in the A…
View article: The role of a low-level jet for stirring the stable atmospheric surface layer in the Arctic
The role of a low-level jet for stirring the stable atmospheric surface layer in the Arctic Open
In this study, we analyze the transition of a stable atmospheric boundary layer (ABL) with a low-level jet (LLJ) to a traditional stable ABL with a classic Ekman helix in the late-winter central Arctic. Vertical profiles in the ABL were me…
View article: Thermodynamics of Evaporation from the Ocean Surface
Thermodynamics of Evaporation from the Ocean Surface Open
Adopted by the Intergovernmental Oceanographic Commission (IOC) of UNESCO in 2010 and the International Union of Geodesy and Geophysics (IUGG) in 2011, the Thermodynamic Equation of Seawater 2010 (TEOS-10) is the current geophysical standa…
View article: What Is a Cloud? Toward a More Precise Definition
What Is a Cloud? Toward a More Precise Definition Open
There are a couple of reasons to stimulate a discussion about the definition of clouds. One reason is that the American Meteorological Society (AMS) and the World Meteorological Organization (WMO) define clouds differently, and that in two…
View article: Relative Humidity: A Control Valve of the Steam Engine Climate
Relative Humidity: A Control Valve of the Steam Engine Climate Open
In the words of Heinrich Hertz in 1885, the Earth is a “gigantic steam engine”. On average, of the planet’s cross section exposed to sunlight, 72 % belong to the global ocean. With a delay of only 2-3 months, most of the heat absorbed ther…
View article: Analytical Determination of the Nucleation-Prone, Low-Density Fraction of Subcooled Water
Analytical Determination of the Nucleation-Prone, Low-Density Fraction of Subcooled Water Open
Subcooled water is the primordial matrix for ice embryo formation by homogeneous and heterogeneous nucleation. The knowledge of the specific Gibbs free energy and other thermodynamic quantities of subcooled water is one of the basic prereq…
View article: Ice-Crystal Nucleation in Water: Thermodynamic Driving Force and Surface Tension. Part I: Theoretical Foundation
Ice-Crystal Nucleation in Water: Thermodynamic Driving Force and Surface Tension. Part I: Theoretical Foundation Open
A recently developed thermodynamic theory for the determination of the driving force of crystallization and the crystal–melt surface tension is applied to the ice-water system employing the new Thermodynamic Equation of Seawater TEOS-10. T…
View article: Ice-Crystal Nucleation in Water: Thermodynamic Driving Force and Surface Tension
Ice-Crystal Nucleation in Water: Thermodynamic Driving Force and Surface Tension Open
A recently developed thermodynamic theory for the determination of the driving force of crystallization and the crystal–melt surface tension is applied to the ice–water system employing the new Thermodynamic Equation of Seawate…
View article: PHYSICAL INTERPRETATION OF ICE CONTACT ANGLES, FITTED TO EXPERIMENTAL DATA ON IMMERSION FREEZING OF KAOLINITE PARTICLES
PHYSICAL INTERPRETATION OF ICE CONTACT ANGLES, FITTED TO EXPERIMENTAL DATA ON IMMERSION FREEZING OF KAOLINITE PARTICLES Open
Previous cloud chamber experiments on freezing of supercooled cloud droplets with single immersed, size-selected 400 nm and 800 nm kaolinite particles revealed a sigmoidal increase of the fraction of frozen cloud droplets with decreasing t…
View article: Metrological challenges for measurements of key climatological observables. Part 4: atmospheric relative humidity
Metrological challenges for measurements of key climatological observables. Part 4: atmospheric relative humidity Open
Water in its three ambient phases plays the central thermodynamic role in the terrestrial climate system. Clouds control Earth's radiation balance, atmospheric water vapour is the strongest "greenhouse" gas, and non-equilibrium relative hu…
View article: Metrological challenges for measurements of key climatological observables: oceanic salinity and pH, and atmospheric humidity. Part 1: overview
Metrological challenges for measurements of key climatological observables: oceanic salinity and pH, and atmospheric humidity. Part 1: overview Open
Water in its three ambient phases plays the central thermodynamic role in the terrestrial climate system. Clouds control Earth's radiation balance, atmospheric water vapour is the strongest "greenhouse" gas, and non-equilibrium relative hu…
View article: Determination of interfacial parameters of a soluble particle in a nonideal solution from measured deliquescence and efflorescence humidities
Determination of interfacial parameters of a soluble particle in a nonideal solution from measured deliquescence and efflorescence humidities Open
In order to study the growth/shrinking of a hygroscopic nanoparticle during hydration/dehydration in an atmosphere of water vapour, we have employed a thermodynamic approach proposed by Shchekin et al. (2008). This approach uses the mechan…