Observation of the Falling Motion of Early Snow Flakes

Kajikawa, Masahiro

doi:10.2151/jmsj1965.60.2_797

Cited by 39 publications

(12 citation statements)

References 11 publications

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“…The moving objects may may be rigid or fluid. They may also span many length scales: from macroscopic, such as snowflakes [1] or sediments [2], to micron-sized, such as water droplets and aerosols in clouds [3,4]. A new frontier arises in the context of micro-and nano-scale machinery [5,6] which sometimes involves flows through narrow pores.…”

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confidence: 99%

Motion of grains, droplets, and bubbles in fluid-filled nanopores

Sushko

Cieplak

2001

Phys. Rev. E

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Molecular dynamics studies of nono-sized rigid grains, droplets and bubbles in nano-sized pores indicate that the drag force may have a hydrodynamic form if the moving object is dense and small compared to the pore diameter. Otherwise, the behavior is non-hydrodynamic. The terminal speed is insensitive to whether the falling droplet is made of liquid or a solid. The velocity profiles within droplets and bubbles that move in the pore are usually non-parabolic and distinct from those corresponding to individual fluids. The density profiles indicate motional shape distortion of the moving objects.

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confidence: 99%

Motion of grains, droplets, and bubbles in fluid-filled nanopores

Sushko

Cieplak

2001

Phys. Rev. E

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“…This suggests that one crystal attaches near the center of another crystal because of the small difference in their falling velocities. Kajikawa (1982) found that 70% snowflakes consisting of two crystals show spiral or rotati o nal falling . The relationship between the nondimensi o nal amplitude (a' = a/ d) of the spiral motion and S is shown in Figure 4, where a is the amplitude of the spiral path, d the size of the snowflakes.…”

Section: Snowflakes Consisting Of Two Crystalsmentioning

confidence: 99%

“…Higuchi (1955Higuchi ( , 1960 observed initial growth stages of snowflakes and calculated the probability of aggregation between two crystals of the plane type. Recently, Kajikawa (1982) observed free-fall pattern of early snowflakes by a stereophotogrammetric method. He found that about 80% of snowflakes fall with spiral or rotational motion.…”

Section: Introductionmentioning

confidence: 99%

“…The purpose of this study is to analyze relations between the structure and the falling motion of early snowflakes based on previous observation (Kajikawa 1982). The data used in this analysis were obtained at Mt Teine observatory (1024 m a.s.1.)…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Kajikawa (1982) observed free-fall pattern of early snowflakes by a stereophotogrammetric method. He found that about 80% of snowflakes fall with spiral or rotational motion.The purpose of this study is to analyze relations between the structure and the falling motion of early snowflakes based on previous observation (Kajikawa 1982). The data used in this analysis were obtained at Mt Teine observatory (1024 m a.s.1.)…”

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confidence: 99%

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Structure and Falling Motion of Early Snowflakes

Kajikawa

1985

A. Glaciology.

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Relations between the structure and falling motion of early snowflakes, ie those composed of a few crystals, were investigated to clarify their growth process .The following results were obtained: (I) Two crystals of the same shape in a snowflake are similar in size, but those of different shape are considerably different in size. (2) In snowflakes having two crystals of the same shape, one crystal is attached near the center of the other; where the two are of different shapes, a smaller crystal is attached near the tip of the other. (3) The nondimensional amplitude of the spiral falling motion of snowflakes composed of two crystals of different shape, is slightly larger than for those with crystals of the same shape. This suggests that snowflakes composed of different shapes are more likely to aggregate to other snowflakes or crystals. (4) In snowflakes consisting of three crystals, the centers are usually arranged in a straight line. (5) The nondimensional amplitude of the spiral motion of snowflakes consisting of three crystals increases with departures from the straight-line arrangement of their centers. INTRODUCTIONAs a basic study for the growth process of snowflakes, it is important to analyze the structure and falling motion of early snowflakes, ie those composed of a few crystals. Magono and Oguchi (1955) observed the combined state of crystals in snowflakes and found that branches of dendritic crystals play a leading role in their aggregation. Higuchi (1955Higuchi ( , 1960 observed initial growth stages of snowflakes and calculated the probability of aggregation between two crystals of the plane type. Recently, Kajikawa (1982) observed free-fall pattern of early snowflakes by a stereophotogrammetric method. He found that about 80% of snowflakes fall with spiral or rotational motion.The purpose of this study is to analyze relations between the structure and the falling motion of early snowflakes based on previous observation (Kajikawa 1982). The data used in this analysis were obtained at Mt Teine observatory (1024 m a.s.1.) of Hokkaido University, during periods of continuous snowfall. Large snowflakes were not involved.

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Estimating snow microphysical properties using collocated multisensor observations

et al. 2014

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The ability of ground-based in situ and remote sensing observations to constrain microphysical properties for dry snow is examined using a Bayesian optimal estimation retrieval method. Power functions describing the variation of mass and horizontally projected area with particle size and a parameter related to particle shape are retrieved from near-Rayleigh radar reflectivity, particle size distribution, snowfall rate, and size-resolved particle fall speeds. Algorithm performance is explored in the context of instruments deployed during the Canadian CloudSat CALIPSO Validation Project, but the algorithm is adaptable to other similar combinations of sensors. Critical estimates of observational and forward model uncertainties are developed and used to quantify the performance of the method using synthetic cases developed from actual observations of snow events. In addition to illustrating the technique, the results demonstrate that this combination of sensors provides useful constraints on the mass parameters and on the coefficient of the area power function but only weakly constrains the exponent of the area power function and the shape parameter. Information content metrics show that about two independent quantities are measured by the suite of observations and that the method is able to resolve about eight distinct realizations of the state vector containing the mass and area power function parameters. Alternate assumptions about observational and forward model uncertainties reveal that improved modeling of particle fall speeds could contribute substantial improvements to the performance of the method.

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Observation of the Falling Motion of Early Snow Flakes

Cited by 39 publications

References 11 publications

Motion of grains, droplets, and bubbles in fluid-filled nanopores

Motion of grains, droplets, and bubbles in fluid-filled nanopores

Structure and Falling Motion of Early Snowflakes

Estimating snow microphysical properties using collocated multisensor observations

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