scholarly journals New Hailstone Physics. Part I: Heat and Mass Transfer (HMT) and Growth

2014 ◽  
Vol 71 (4) ◽  
pp. 1508-1520 ◽  
Author(s):  
Roland List
Keyword(s):  
Mass Transfer ◽  
Water Content ◽  
Heat And Mass Transfer ◽  
Liquid Water ◽  
Collection Efficiency ◽  
Free Fall ◽  
Liquid Water Content ◽  
Homogeneous Surface ◽  
Surface Temperatures ◽  
Ice Fraction

Abstract An all-encompassing new theory of heat and mass transfer (HMT) and growth equations have been developed for freely falling spherical hailstones with diameters of 0.5–8 cm. The initial six variables are diameter, liquid water content, air and hailstone surface temperatures, net collection efficiency, and ice fraction of spongy deposit. They are replaced by three or four new ones, depending on the three growth categories. Two new variables are products of “old” ones: (i) the square root of the Reynolds number Re and the liquid water content and (ii) net collection efficiency and ice fraction of the spongy deposit. Only the products matter, not the individual parts. [The two variables in (ii) are as important as the two in (i).] Two old variables remain: air and surface temperatures. The HMT can be further compacted for hailstorms with specified pressure–air temperature–height profiles. Further, Re for free-fall reveals unexpected complexities—issues important to solve HMT problems. The “new hailstone physics” is based on 55 years of in-house studies of all aspects of hailstone growth, followed by 5 years of shaping these puzzle pieces and assembling them into a coherent picture. This was only possible by recognizing the free-fall mode: a special gyration that allows hailstones to grow with a radial symmetry and, thus, homogeneous surface temperature. Part II will display the surprising solutions to growth and HMT and firmly link the hailstones to mostly spongy growth with shedding that favors a hail-coupled rain mechanism.

scholarly journals Response of the Nevzorov hot wire probe in Arctic clouds dominated by very large droplet sizes

2009 ◽  
Vol 2 (3) ◽  
pp. 1293-1320
Author(s):  
A. Schwarzenboeck ◽  
G. Mioche ◽  
A. Armetta ◽  
A. Herber ◽  
J.-F. Gayet
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Collection Efficiency ◽  
Supercooled Liquid ◽  
Liquid Water Content ◽  
The Arctic ◽  
Asymmetry Factor ◽  
Pure Liquid ◽  
Hot Wire ◽  
Data Set

Abstract. During the airborne research mission ASTAR 2004 (Arctic Study of Tropospheric Aerosols, Clouds and Radiation) performed over the island of Svalbard in the Arctic a constant-temperature hot-wire Nevzorov Probe designed for aircraft measurements, has been used onboard the aircraft POLAR 2. The Nevzorov probe measured liquid water (LWC) and total condensed water content (TWC) in supercooled liquid and partly mixed phase clouds, respectively. As for other hotwire probes the calculation of LWC and/or TWC (and thus the ice water content IWC) has to take into account the collection efficiencies of the two separate sensors for LWC and TWC which both react differently with respect to cloud phase and what is even more difficult to quantify with respect to the size of ice and liquid cloud particles. The study demonstrates that during pure liquid cloud sequences the ASTAR data set of the Nevzorov probe allowed to improve the quantification of the collection efficiency, particularly of the LWC probe part with respect to water. The improved quantification of liquid water content should lead to improved retrievals of IWC content. Simultaneous retrievals of LWC and IWC are correlated with the asymmetry factor derived from the Polar Nephelometer instrument.

scholarly journals Response of the Nevzorov hot wire probe in clouds dominated by droplet conditions in the drizzle size range

2009 ◽  
Vol 2 (2) ◽  
pp. 779-788 ◽  
Author(s):  
A. Schwarzenboeck ◽  
G. Mioche ◽  
A. Armetta ◽  
A. Herber ◽  
J.-F. Gayet
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Collection Efficiency ◽  
Supercooled Liquid ◽  
Liquid Water Content ◽  
The Arctic ◽  
Asymmetry Factor ◽  
Pure Liquid ◽  
Hot Wire ◽  
Data Set

Abstract. During the airborne research mission ASTAR 2004 (Arctic Study of Tropospheric Aerosols, Clouds and Radiation) performed over the island of Svalbard in the Arctic a constant-temperature hot-wire Nevzorov Probe designed for aircraft measurements, has been used onboard the aircraft POLAR 2. The Nevzorov probe measured liquid water (LWC) and total condensed water content (TWC) in supercooled liquid and partly mixed phase clouds, respectively. As for other hotwire probes the calculation of LWC and/or TWC (and thus the ice water content IWC) has to take into account the collection efficiencies of the two separate sensors for LWC and TWC which both react differently with respect to cloud phase and what is even more difficult to quantify with respect to the size of ice and liquid cloud particles. The study demonstrates that during pure liquid cloud sequences the ASTAR data set of the Nevzorov probe allowed to improve the quantification of the collection efficiency, particularly of the LWC probe part with respect to water. The improved quantification of liquid water content should lead to improved retrievals of IWC content. Simultaneous retrievals of LWC and IWC are correlated with the asymmetry factor derived from the Polar Nephelometer instrument.

scholarly journals Three phase heat and mass transfer model for unsaturated soil freezing process: Part 1 - model development

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 75-83 ◽  
Author(s):  
Fei Xu ◽  
Yaning Zhang ◽  
Guangri Jin ◽  
Bingxi Li ◽  
Yong-Song Kim ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Water Content ◽  
Heat And Mass Transfer ◽  
Unsaturated Soil ◽  
Liquid Water ◽  
Soil Freezing ◽  
Freezing Process ◽  
Moisture Migration ◽  
Water Fraction ◽  
Three Phase

Abstract A three-phase model capable of predicting the heat transfer and moisture migration for soil freezing process was developed based on the Shen-Chen model and the mechanisms of heat and mass transfer in unsaturated soil freezing. The pre-melted film was taken into consideration, and the relationship between film thickness and soil temperature was used to calculate the liquid water fraction in both frozen zone and freezing fringe. The force that causes the moisture migration was calculated by the sum of several interactive forces and the suction in the pre-melted film was regarded as an interactive force between ice and water. Two kinds of resistance were regarded as a kind of body force related to the water films between the ice grains and soil grains, and a block force instead of gravity was introduced to keep balance with gravity before soil freezing. Lattice Boltzmann method was used in the simulation, and the input variables for the simulation included the size of computational domain, obstacle fraction, liquid water fraction, air fraction and soil porosity. The model is capable of predicting the water content distribution along soil depth and variations in water content and temperature during soil freezing process.

scholarly journals Proof of Concept: Development of Snow Liquid Water Content Profiler Using CS650 Reflectometers at Caribou, ME, USA

Sensors ◽  
2017 ◽  
Vol 17 (3) ◽  
pp. 647 ◽  
Author(s):  
Carlos Pérez Díaz ◽  
Jonathan Muñoz ◽  
Tarendra Lakhankar ◽  
Reza Khanbilvardi ◽  
Peter Romanov
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Concept Development ◽  
Proof Of Concept

Field Measurement of the Liquid-Water Content of Snow

1981 ◽  
Vol 27 (95) ◽  
pp. 175-178 ◽  
Author(s):  
E. M. Morris
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Field Measurement ◽  
Solution Method ◽  
Liquid Water Content ◽  
Field Trials

Abstract Field trials show that the liquid-water content of snow can be determined simply and cheaply by a version of Bader’s solution method.

scholarly journals Snow dielectric properties: from DC to microwave X-band

1994 ◽  
Vol 19 ◽  
pp. 92-96 ◽  
Author(s):  
TH. Achammer ◽  
A. Denoth
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Frequency Range ◽  
Snow Density ◽  
Cold Room ◽  
X Band ◽  
Grain Size And Shape

Broadband measurements of dielectric properties of natural snow samples near or at 0°C are reported. Measurement quantities are: dielectric permittivity, loss factor and complex propagation factor for electromagnetic waves. X-band measurements were made in a cold room in the laboratory; measurements at low and intermediate frequencies were carried out both in the field (Stubai Alps, 3300 m; Hafelekar near Innsbruck, 2100 m) and in the cold room. Results show that in the different frequency ranges the relative effect on snow dielectric properties of the parameters: density, grain-size and shape, liquid water content, shape and distribution of liquid inclusions and content of impurities, varies significantly. In the low-frequency range the influence of grain-size and shape and snow density dominates; in the medium-frequency range liquid water content and density are the dominant parameters. In the microwave X-band the influence of the amount, shape and distribution of liquid inclusions and snow density is more important than that of the remaining parameters.

Comparison of Water Thickness Profiles of Compressed PEMFC GDLs

2011 ◽  
Author(s):  
Pradyumna Challa ◽  
James Hinebaugh ◽  
A. Bazylak
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Water Distribution ◽  
Polymer Electrolyte Membrane ◽  
Water Injection ◽  
Liquid Water Content ◽  
Gas Diffusion ◽  
Injection Rate ◽  
Water Levels ◽  
Ex Situ

In this paper, through-plane liquid water distribution is analyzed for two polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layers (GDLs). The experiments were conducted in an ex situ flow field apparatus with 1 mm square channels at two distinct flow rates to mimic water production rates of 0.2 and 1.5 A/cm2 in a PEMFC. Synchrotron radiography, which involves high intensity monochromatic X-ray beams, was used to obtain images with a spatial and temporal resolution of 20–25 μm and 0.9 s, respectively. Freudenberg H2315 I6 exhibited significantly higher amounts of water than Toray TGP-H-090 at the instance of breakthrough, where breakthrough describes the event in which liquid water reaches the flow fields. While Freudenberg H2315 I6 exhibited a significant overall decrease in liquid water content throughout the GDL shortly after breakthrough, Toray TGP-H-090 appeared to retain breakthrough water-levels post-breakthrough. It was also observed that the amount of liquid water content in Toray TGP-H-090 (10%.wt PTFE) decreased significantly when the liquid water injection rate increased from 1 μL/min to 8 μL/min.

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