Bryan C. Scott, Peter V. Hobbs,
... among themselves and with water droplets to produce graupel, unrimed and rimed ice crystals and snowflakes. The ... distribution in determining the dominant mechanism for forming graupel embryos. In the maritime cloud, graupel embryos originated on frozen drops produced after collisions with ice crystals. In the continental cloud, graupel embryos tended to originate on ice crystals. The ... the formation and sedimentation of larger drops and graupel. The ejection of four ice splinters during the ... drop (>50 µm) in the maritime cloud, increased graupel concentrations at cloud top by 100 times. When ...
Tópico(s): Atmospheric chemistry and aerosols
1977 - American Meteorological Society | Journal of the Atmospheric Sciences
... were made of the sizes and concentrations of graupel and snow crystals occurring in seeded and untreated ... that crystal riming, and formation and precipitation of graupel, are common to all stages of Sierran snowstorms. Graupel occurs simultaneously with all types of snow crystals, ... with or serve as kernels for particles of graupel.Graupel particles do not develop predominantly on kernel snow ... over relatively long periods by deposition and accretion. Graupel often forms instead on a select few small ...
Tópico(s): Winter Sports Injuries and Performance
1975 - American Meteorological Society | Journal of applied meteorology
E. Sukovich, David E. Kingsmill, Sandra E. Yuter,
Abstract Empirical characterization of graupel and snow in precipitating tropical convective clouds is important for refining satellite precipitation retrieval algorithms and cloud-resolving and radiative ... purpose of identifying ice particle ensembles dominated by graupel or snow particles. These ensembles were accumulated along ... temperatures below 0°C. A third category, mixed graupel/snow, has characteristics between those of the predominately graupel and snow ensembles and can be used either ... DC-8 ensemble data. For the UND Citation, graupel ensembles compose ∼5% of the total with mixed ...
Tópico(s): Meteorological Phenomena and Simulations
2008 - American Meteorological Society | Journal of Applied Meteorology and Climatology
Jason A. Milbrandt, Hugh Morrison,
... A method to predict the bulk density of graupel ρ g has been added to the two- ... Milbrandt–Yau bulk microphysics scheme. The simulation of graupel using the modified scheme is illustrated through idealized ... represent rimed ice, simulations were run for various graupel-only and graupel-plus-hail configurations. Because of the direct feedback ... scheme produces a much different spatial distribution of graupel, with more mass concentrated in the convective region ... capable of representing a realistically wide range of graupel characteristics in various atmospheric conditions without the need ...
Tópico(s): Cryospheric studies and observations
2012 - American Meteorological Society | Journal of the Atmospheric Sciences
Hyunho Lee, Jong‐Jin Baik, Ji‐Young Han,
... basic‐state wind profiles and different aerosol concentrations. Graupel particles account for the most of the cloud ... cases. In the uniform basic‐state wind cases, graupel particles with moderate sizes account for some of the total graupel mass in the cases with TICE, whereas graupel particles with large sizes account for almost all the total graupel mass in the cases without TICE. This is because the growth of ice crystals into small graupel particles is enhanced due to TICE. The changes in the size distributions of graupel particles due to TICE result in a decrease ...
Tópico(s): Particle Dynamics in Fluid Flows
2014 - Wiley | Journal of Geophysical Research Atmospheres
Kenji Suzuki, Midori Matsuo, Eri Nakano, Shunsuke Shigeto, Kosei Yamaguchi, Eiichi NAKAKITA,
Graupel is generally observed as a cone-like shape in clouds, as a result of riming. However, nearly spherical graupel is also observed in clouds. In this study, we focused on the shape of graupel and evaluated it quantitatively using particle images obtained ... were chosen for the analysis. The flattening of graupel (f) and ratios of the graupel cross sections to the ellipsoid-assumed cross sections (r) were calculated on the basis of the graupel shapes observed between 0 °C and − 10 °C. ... convective to stratiform. This indicated that nearly spherical graupel were more likely to be observed in shallow ...
Tópico(s): Meteorological Phenomena and Simulations
2013 - Elsevier BV | Atmospheric Research
Rebecca D. Adams-Selin, Susan C. van den Heever, Richard H. Johnson,
... Forecasting model was tested, with a focus on graupel parameter characteristics. The graupel parameter in one scheme was modified to have ... parameters that are important to operational forecasters to graupel properties: timing of bowing development, system speed, wind ... by as much as 105 min. Simulations containing graupel with smaller mean size and slower fall speed (“graupel like”) bowed earlier due to increased microphysical cooling ... surface with minimal melting, producing the largest accumulations. Graupel-like systems had 10-m wind gusts 73% ...
Tópico(s): Precipitation Measurement and Analysis
2013 - American Meteorological Society | Weather and Forecasting
А. Хаин, Mark Pinsky, M. Shapiro, A. Pokrovsky,
... 300-μm-radius drops, or 700-μm-radius graupel) is presented. It is used for the calculation of graupel–drop collision efficiencies and collision kernels in calm air for low-, medium-, and high-density graupel at 750- and 500-mb pressure levels. Low-density graupel interacts with water droplets in a way similar ... crystals: there exists a cutoff size, below which graupel cannot collect water droplets. The authors have shown ... the cutoff size decreases with the growth of graupel density, so that medium- and high-density graupel ...
Tópico(s): Fluid Dynamics and Heat Transfer
2001 - American Meteorological Society | Journal of the Atmospheric Sciences
... by charge transfers between ice crystals and riming graupel pellets (the noninductive process) has been the subject ... been determined as functions of ice crystal size, graupel/crystal relative velocity, temperature, and the effective liquid ... EW) in the cloud experienced by the riming graupel pellets. We now present results of laboratory studies ... velocity and EW dependence of the sign of graupel charging on temperature. The magnitude of the charge ... from its dependence on the crystal size and graupel velocity, while the sign of the rimer charging ...
Tópico(s): Tree Root and Stability Studies
1998 - American Geophysical Union | Journal of Geophysical Research Atmospheres
Mark Pinsky, А. Хаин, Daniel Rosenfeld, A. Pokrovsky,
The motion of water drops and graupel particles within a turbulent medium is analyzed. The turbulence is assumed to be homogeneous and isotropic. It is demonstrated that the inertia of drops and graupel particles falling within a turbulent flow leads to ... formation of substantial relative velocity between drops and graupel particles. The results of calculations of the continuous growth of raindrops and graupel particles moving within a cloud of small droplets ... for different droplet sizes. In the case of graupel–droplet interaction Eε was assumed equal to 1. ...
Tópico(s): Atmospheric aerosols and clouds
1998 - Elsevier BV | Atmospheric Research
Jiangnan Li, Qingwen Ye, Fangzhou Li, Youlong Chen,
... 2010 and 2011. The influences of low-density graupel (LDG) and high-density graupel (HDG) on autumn precipitation were modeled using the ... sources of rainwater in these simulations are: melting graupel, melting snow, and cloud water collected by rain ... top three rainwater sinks are: rainwater collected by graupel, rainwater collected by snow, and evaporation. The conversion from rain water to graupel makes the largest contribution to precipitation. Three categories of graupel has minor influences on the precipitation area and ...
Tópico(s): Tropical and Extratropical Cyclones Research
2019 - Elsevier BV | Atmospheric Research
Huiyan Xu, Dengrong Zhang, Xiaofan Li,
... rainfall intensity was sensitive to the schemes and graupel and hail parameterizations. This indicates great impacts of microphysics and terminal velocities of graupel/hail on the local rainfall intensity. Upward‐moving graupel had a stronger net source compared to the downward‐moving graupel over the spiral rainband in the Milbrandt‐Yau ... net source was much weaker for upward‐moving graupel than for downward‐moving graupel over the eyewall in the NSSL simulation due ... large terminal velocity. Decreasing the terminal velocities of graupel and hail (if hail exists) in the mid ...
Tópico(s): Climate variability and models
2021 - Wiley | Journal of Geophysical Research Atmospheres
Rebecca D. Adams-Selin, Susan C. van den Heever, Richard H. Johnson,
... development and longevity are examined through changes to graupel parameterization in the Advanced Research Weather Research and ... are performed that test the sensitivity to different graupel size distributions as well as the complete removal of graupel. It is found that size distributions with larger and denser, but fewer, graupel hydrometeors result in a weaker cold pool due ... to tilt rearward, and thus bowing occurs later. Graupel size distributions with more numerous, smaller, and lighter ... A sensitivity test with fast-falling but small graupel hydrometeors revealed that small mean size and slow ...
Tópico(s): Cryospheric studies and observations
2012 - American Meteorological Society | Monthly Weather Review
Stewart G. Cober, Roland List,
Rigidly suspended conical graupel were grown in a wind tunnel, starting from 1-mm hexagonal plates, with liquid water content varied from 0. ... chosen to simulate natural conditions in which conical graupel grow and serve as embryos for hail. Final graupel diameters ranged from 1.5 to 6 mm, ... angle were parameterized in terms of the relative graupel-airstream velocity, the cloud-droplet median volume radius, ... C and are the first ever of growing graupel. The bulk collection efficiency was found to be ... mass transfer equations for the laboratory-grown conical graupel and can be used to improve graupel growth ...
Tópico(s): Fluid Dynamics and Heat Transfer
1993 - American Meteorological Society | Journal of the Atmospheric Sciences
Abstract Snow avalanches with failure layers including graupel are sometimes observed in Japan. A snow layer including graupel may be formed close to the melting point (0°C) after passage of a cold front with cumulus clouds. Graupel particles have a large diameter and a spherical ... this paper, characteristics of snow layers that include graupel are described by angle of repose, shear frame ... of the grain-size. This suggests that a graupel layer near 0°C will not be formed ... slope exceeding 45°. SFI data for three different graupel layers were measured over 1–3 days for ...
Tópico(s): Winter Sports Injuries and Performance
2004 - Cambridge University Press | Annals of Glaciology
Mariko Oue, Matthew R. Kumjian, Yinghui Lu, Zhiyuan Jiang, Eugene E. Clothiaux, Johannes Verlinde, Kültegin Aydin,
Abstract Characteristics of graupel in an Arctic deep mixed-phase cloud on 7 December 2013 were identified with observations from an X-band ... dimensions, were consistent with small, slow-falling conical graupel coexisting with low concentrations of more isometric graupel. The observed negative K DP values were best matched by scattering calculations for small, dense conical graupel with 30°–40° cone angles. The positive K ... and the Doppler spectra indicate that large isometric graupel coexisted with a second population of slower-falling ...
Tópico(s): Aeolian processes and effects
2015 - American Meteorological Society | Journal of Applied Meteorology and Climatology
Tsutomu Takahashi, Soichiro Sugimoto, Tetsuya Kawano, Kenji Suzuki,
... System network data. The main charge carriers were graupel particles and ice crystals, and space charge increased ... negative in the middle level (carried by negative graupel and negative ice crystals), and positive in the lower level (carried by positive graupel). Lightning was only seen in clouds that had ... ice crystal number concentration >500 m −3 , and graupel particle number concentration >20 m −3 . Predominance of ... cloud‐to‐ground (+CG) lightning was associated with graupel number concentration <200 m −3 and graupel peak ...
Tópico(s): Atmospheric aerosols and clouds
2019 - Wiley | Journal of Geophysical Research Atmospheres
Anders A. Jensen, Gregory Thompson, Kyoko Ikeda, Sarah A. Tessendorf,
... explored. A new two-moment and predicted density graupel category is implemented into the Thompson–Eidhammer scheme. Additionally, the one-moment graupel category’s intercept parameter is modified, based on hail observations, to shift the properties of the graupel category to become more hail-like since the category is designed to represent both graupel and hail. Finally, methods to diagnose maximum expected ... the newly implemented two-moment and predicted density graupel version, and the modified (to be more hail- ...
Tópico(s): Climate variability and models
2023 - American Meteorological Society | Monthly Weather Review
Alexander Theis, Miklós Szakáll, K. Diehl, Subir K. Mitra, Florian Zanger, Andrew J. Heymsfield, Stephan Borrmann,
... to investigate the melting of low-density lump graupel while floating at their terminal velocities. The graupel characteristics such as maximum dimension, density, and axis ... melting process on relative humidity, lapse rate, initial graupel density, and graupel size. In dependence on these parameters, the total ... 1200 m for typical conditions of a falling graupel. Significance Statement The accuracy of weather forecast models ... study, we investigated the melting of low-density graupel, which constitute an important class of precipitation particles. ...
Tópico(s): Aeolian processes and effects
2022 - American Meteorological Society | Journal of the Atmospheric Sciences
Embryos of graupel particles were studied by the thin section technique under a polarization microscope and direct observation by picking graupel particles apart under a microscope. Snow crystals and a frozen drop were picked out from graupel particles. They were considered as embryos morphologically. And ... calculations that they satisfy the condition for the graupel growth. According to the embryo and falling behavior of graupel, the formation of graupel was classified and a few formation mechanisms were ...
Tópico(s): Animal Genetics and Reproduction
1976 - The Meteorological Society of Japan | Journal of the Meteorological Society of Japan Ser II
The processes of development of graupel and had which fell to the ground from a storm in northeastern Colorado on 22 July 1976 are investigated over a ... dimensional wind fields. The growth conditions that these graupel and hail (spherical ice particles smaller than and ... The terming velocities of the particles which become graupel are not as well-matched to the parcel ... with lower liquid water contents. Embryos of the graupel and hail are found to be aggregates (snowflakes) ... region, wherein they complete their development. Aggregates becoming graupel are ingested directly by the main updrafts. Mechanisms ...
Tópico(s): Meteorological Phenomena and Simulations
1983 - American Meteorological Society | Journal of the Atmospheric Sciences
Conrad L. Ziegler, Donald R. MacGorman, J. E. Dye, Peter S. Ray,
The role of noninductive graupel‐ice charge separation in the early electrification of the July 31, 1984, New Mexico mountain thunderstorm is assessed with a ... and sizes, arising from vigorous precipitation growth, accelerates graupel‐ice collision rates and hence the noninductive charging rate. Growing graupel particles experience increasing fall speed as they rise ... the updraft. The resulting vertical flux convergence of graupel containing charge from previous noninductive collisions is a ... rate and by the separation of negatively charged graupel and positively charged smaller ice particles by differential ...
Tópico(s): Fire effects on ecosystems
1991 - American Geophysical Union | Journal of Geophysical Research Atmospheres
Daniel E. Johnson, Pao K. Wang, Jerry M. Straka,
... of the storm hydrometeor mass is ice, with graupel and hail being the most predominant type. The total mass of ice, snow, graupel and hail increase rapidly with storm intensity, while ... produced primarily from the melting and shedding of graupel and hail, snow is primarily initiated by the ... accretion of cloud ice and cloud water, and graupel and hail is primarily initiated through rain-snow ... The largest sinks are evaporation and accretion by graupel and hail for rain water, sublimation and accretion ...
Tópico(s): Climate variability and models
1994 - Elsevier BV | Atmospheric Research
... the sign of charge acquired by a riming graupel pellet during ice crystal interactions depends on its ... Calculations of the heat balance of the simulated graupel pellets are considered in terms of experimental measurements ... droplets is not always adequate to enable the graupel surface to grow by vapor diffusion in all ... and the shape and surface roughness of the graupel may play important roles in determining the surface ... overall sign of the charge transfer. Furthermore, the graupel charges negatively under specific conditions where it is ...
Tópico(s): Icing and De-icing Technologies
1993 - American Meteorological Society | Journal of the Atmospheric Sciences
R. Mitzeva, C. P. R. Saunders, Boryana Tsenova,
... saturation to the sign of charge transfer during graupel/ice crystal interactions in thunderstorms. Previous laboratory studies ... vapour diffusion in a supersaturated environment while the graupel surface grows by diffusion under low accretion rate ... will sublimate when heated sufficiently by riming. The graupel surface is also influenced, even under net sublimation ... diffusional growth rates of ice crystals and riming graupel particles are calculated for various cloud saturation ratios, ... the sign of electric charge transferred during crystal/graupel collisions is determined according to the concept of ...
Tópico(s): Wind and Air Flow Studies
2005 - Elsevier BV | Atmospheric Research
Hsin-Mu Lin, Pao K. Wang, Robert E. Schlesinger,
... hydrometeor classes (cloud water, cloud ice, rain, snow, graupel/hail), along with the individual sources (and sinks) of the three precipitating hydrometeor classes (rain, snow, graupel/hail) are analyzed in detail. These analyses encompass ... time-averaged sense, ice hydrometeors (cloud ice, snow, graupel/hail) account for ∼ 70–80% of the total ... The dominant rain sources are two of the graupel/hail sinks, shedding and melting, in both High ... are accretion by hail and evaporation. The dominant graupel/hail sources are accretion of rain, snow and ...
Tópico(s): Plant Water Relations and Carbon Dynamics
2005 - Elsevier BV | Atmospheric Research
Zhaoxia Zeng, Sandra E. Yuter, Robert A. Houze, David E. Kingsmill,
... portions of the storm volumes that included hail, graupel, and supercooled rain. By comparing the results of ... indirectly validated. The microphysical development of hail and graupel was similar for both the single isolated cell ... subsequently froze. These frozen drops became hail and graupel embryos and continued to grow by accretion. Supercooled ... km above the 0°C level. Hail and graupel appeared several minutes after the first appearance of supercooled rain. Graupel was present at higher altitudes and encompassed a ...
Tópico(s): Climate variability and models
2001 - American Meteorological Society | Monthly Weather Review
Melina Y. Luque, Rodrigo E. Bürgesser, Eldo E. Ávila,
... measurements of the charge separation during ice crystal–graupel collisions in the absence of supercooled water droplets. ... of the average charge acquired by a simulated graupel, under condition of subsaturation with respect to water ... s −1 between the ice particles and the graupel. The aim of the measurements was to study ... previous findings indicate that the sign of the graupel charging depends on the presence/absence of supercooled ... these new results confirm the negative charging of graupel under these conditions. It was found that the ...
Tópico(s): Fire dynamics and safety research
2016 - Wiley | Quarterly Journal of the Royal Meteorological Society
V. N. Bringi, Patrick C. Kennedy, G. J. Huang, Cameron Kleinkort, Merhala Thurai, Branislav M. Notaroš,
Abstract Comprehensive analysis of an unusual graupel-shower event recorded by an S-band polarimetric radar and two optical-imaging surface instruments is presented. The primary radar characteristic was ... composed primarily of small (8–15-mm diameter) graupel affected the ground instrumentation site that was established ... the reflectivity-weighted mean axis ratios of the graupel particles in this event remained somewhat prolate throughout ... the diameters, shapes, and fall speeds of the graupel particles as they reached the surface. The graupel ...
Tópico(s): Atmospheric aerosols and clouds
2016 - American Meteorological Society | Journal of Applied Meteorology and Climatology
Jing Sun, Zheng Shi, Jian Chai, Guirong Xu, Ben Niu,
... cloud process is initiated mainly by production of graupel, and the microphysical parameterizations are used to predict ... of cloud droplets, rain, ice crystals, snow, and graupel. The simulations results show that 80% rainfall is ... area of LWC matches the distribution range of graupel particles. However, the growth of graupel particles depend on the microphysical processes of nucleation and propagation between rain and graupel particles (NUrg) and collision and coalescence between cloud droplets and graupel (CLcg), in which NUrg is a major source ...
Tópico(s): Tropical and Extratropical Cyclones Research
2016 - Multidisciplinary Digital Publishing Institute | Atmosphere