Free-Fall Behavior of Planar Snow Crystals, Conical Graupel and Small Hail

List, Roland; Schemenauer, Robert S.

doi:10.1175/1520-0469(1971)028<0110:ffbops>2.0.co;2

Cited by 127 publications

(80 citation statements)

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“…13c), whereas all slow-falling ice pellets exhibited nearly sideway orientations (Fig. 13g), as reported by List and Schemenauer (1971). Fractured particles were rarely found in the fast-falling group, whereas the slow-falling group exhibited several types of fracture (Figs.…”

Section: Characteristicssupporting

confidence: 77%

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Microphysical Properties of Slow-Falling and Fast-Falling Ice Pellets Formed by Freezing Associated with Evaporative Cooling

Nagumo

Fujiyoshi

2015

Monthly Weather Review

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This paper describes a numerical and observational study focused on ice-pellet formation and microphysical properties near 08C from an ice-pellet-dominated storm associated with an unusually warm and dry atmosphere on 10 April 2005, in Sapporo, Japan. A one-dimensional numerical model simulation indicated that precipitation particle temperatures were sensitive to environmental temperature and relative humidity and close to the wet-bulb temperature. The simulation demonstrated that completely melted snowflakes could refreeze by evaporative cooling. Moreover, initial freezing could be explained by contact ice nucleation at the height of the minimum wet-bulb temperature.Observations using a 2D video distrometer (2DVD) indicated that ice pellets exhibited two modes of fall velocities at surface temperatures near 08C during the same time period: slow falling and fast falling. The slowfalling ice pellets exhibited a velocity similar to the average terminal velocity of hail, whereas the velocities of the fast-falling ice pellets were closer to those of raindrops. Surface roundness and fracturing characteristics of ice pellets suggest that slow-falling ice pellets froze rapidly and uniformly in a relatively cold dry layer with a wet-bulb temperature near 248C. In contrast, the fast-falling ice pellets exhibited the properties of ice particles with a wet smooth surface, suggesting that they froze slowly in a relatively warm layer by contacting ice crystals or splinters generated by preceding slow-falling ice pellets.

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Section: Characteristicssupporting

confidence: 77%

“…Another factor that increases the drag coefficient is tumbling motion (List and Schemenauer 1971). This occurs when freezing drops coagulate (Spengler and Gokhale 1972) and turn to dry ice particles (Bringi and Chandrasekar 2001;Straka 2009;Anderson et al 2011;Ryzhkov et al 2011).…”

Section: ) Properties Of Ice Pellets Derived From Fall Velocitiesmentioning

confidence: 99%

Microphysical Properties of Slow-Falling and Fast-Falling Ice Pellets Formed by Freezing Associated with Evaporative Cooling

Nagumo

Fujiyoshi

2015

Monthly Weather Review

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“…The unstable falling motion at first clearly appears as an oscillation about the axis in the plane of the plate-like crystals, as revealed by the model experiments (e.g., Podzimek, 1965Podzimek, , 1968Podzimek, , 1984List and Schemenauer, 1971) . The Reynolds number Re at the beginning of oscillation, however, is considerably smaller than the value (about 100) found in model experiments.…”

Section: 1mentioning

confidence: 71%

“…When comparisons are made between the above results, including the case of graupel (Kajikawa, 1977(Kajikawa, , 1980 and laboratory model experiments (e.g., Mason, 1965, 1966;Podzimek, 1965Podzimek, , 1968Podzimek, , 1984List and Schemenauer, 1971) with respect to the falling motion of snow crystals, it appears that the difference between the two occurs in the range of unstable motion.…”

Section: Introductionmentioning

confidence: 97%

Observations of the Falling Motion of Plate-Like Snow Crystals Part I: The Free-Fall Patterns and Velocity

Kajikawa

1992

Journal of the Meteorological Society of Japan

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Free-fall patterns and the variations in the vertical and horizontal velocities of unrimed plate-like snow crystals were analyzed by means of a stereo-photogrammetric method.Whether the crystals exhibit a stable falling motion or not mainly depends on the Best number, which involves the mean vertical velocity (fall velocity), and the non-dimensional moment of inertia of the crystals.Unstable fall patterns were roughly classified into three types: nonrotation, swing, and rotation or spiral. For dendritic shaped crystals, the distinction among these types is approximately determined by the combination of the non-dimensional moment of inertia and the Reynolds number, which involves the mean vertical velocity.Although the standard deviation of the vertical velocity for dendritic shaped crystals was very small (1 to 3% of the mean vertical velocity), that of the horizontal velocity was considerably larger, measuring 5 to 20% of the mean vertical velocity. Accordingly, it appears likely that the variation in the horizontal velocity plays an important role in the random aggregation of plate-like snow crystals having almost the same shape and size.

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“…(e. g., Willmarth, Hawk and Harvey 1964 ;Podzimek 1965Podzimek , 1968Jayaweera and Mason 1968;List and Schemenauer 1971;Sasys5 1971).…”

Section: Introductionmentioning

confidence: 99%

The Collection Efficiency of Simulated Snow Particles for Water Droplets (II)

Sasyo¹

1977

Pap.Met.Geophy

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The oscillatory angular motion of the snowflake is determined by a stereophotographic technique, in order to investigate the effect of the orientation of a falling snow particle on its collection efficiency.The results are summerized as follows :1) The frequency distribution of the amplitude of oscillatory angular motion extends to about 35° but the modal amplitude lies in the region from 0° to 5°.2) Frequency distributions of the angular velocities both about the vertical and the horizontal axis are bimodal type.3) In the frequency distribution of the angular velocity about the vertical axis, the first modal velocity lies in the range less than 2.5 rad/sec and the second in 7. 5 rad/sec to 10 rad/sec. Their mean velocity is 3. 45 rad/sec. The angular velocity less than 2. 5 rad/sec has a frequency of occurrence larger than 50% and the angular velocity less than 5. 0 rad/sec has one larger than 88%. 4) In the distribution of angular velocity about the horizontal axis, the first modal velocity lies in the range from 5.0 rad/sec to 7. 5 rad/sec and the second in the range from 17. 5 rad/sec 20. 0 rad/sec.The mean velocity is 9. 85 rad/sec and is about 3 times that about the vertical axis.

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Free-Fall Behavior of Planar Snow Crystals, Conical Graupel and Small Hail

Cited by 127 publications

References 0 publications

Microphysical Properties of Slow-Falling and Fast-Falling Ice Pellets Formed by Freezing Associated with Evaporative Cooling

Microphysical Properties of Slow-Falling and Fast-Falling Ice Pellets Formed by Freezing Associated with Evaporative Cooling

Observations of the Falling Motion of Plate-Like Snow Crystals Part I: The Free-Fall Patterns and Velocity

The Collection Efficiency of Simulated Snow Particles for Water Droplets (II)

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