Snowflake Research Articles

Snow accumulation on a narrow board

In calm weather falling snow flakes sometimes bounce even on the soft surface of freshly deposited snow. Activity of such bouncing snow flakes influences the efficiency of snow accumulation on a narrow board. Snow flakes which fall on the board near the edge frequently jump over the edge. Activity of bouncing increases and cohesion decreases as temperature falls. Consequently, the amount of snow accumulation on a unit area of a board reduces with decreasing width of the board and falling temperature. It was found impossible for snow flakes to accumulate on the board when its width was narrower than the critical value.

Real time design and animation of fractal plants and trees

The goal of science is to understand why things are the way they are. By emulating the logic of nature, computer simulation programs capture the essence of natural objects, thereby serving as a tool of science. When these programs express this essence visually, they serve as an instrument of art as well.This paper presents a fractal computer model of branching objects. This program generates pictures of simple orderly plants, complex gnarled trees, leaves, vein systems, as well as inorganic structures such as river deltas, snow flakes, etc. The geometry and topology of the model are controlled by numerical parameters which are analogous to the organism's DNA. By manipulating the genetic parameters, one can modify the geometry of the object in real time, using tree based graphics hardware. The random effects of the environment are taken into account, to produce greater diversity and realism. Increasing the number of significant parameters yields more complex and evolved species.The program provides a study in the structure of branching objects that is both scientific and artistic. The results suggest that organisms and computers deal with complexity in similar ways.

No pattern yet for snowflakes

No pattern yet for snowflakes

No pattern yet for snowflakes

No pattern yet for snowflakes

初期雪片の落下運動の観測

Free-fall pattern of early snow flakes, which were composed of two to six crystals, were observed by a stereophotogrammetric method.The considerable part (about 80%) of analysed snow flakes showed the fall pattern of spiral type or rotation type. On the other hand, the stable motion (the fall pattern without horizontal movements) was only observed in the small number of snow flakes composed of two crystals. Whether those snow flakes show the stable motion or not depend on Reynolds number of mean vertical motion, the combined state and the ratio of sizes of two component crystals.The nondimensional frequency and the period of spiral motion increased in proportion to Reynolds number and the nondimensional amplitude of spiral path, respectively. Moreover, the displacement velocity of spiral axis increased proportionally to the falling velocity of early snow flakes.

Large rain drops in the bright band

It has recently been suggested1–3, based on dual-polarized radar measurements, that in the bright-band region, melting snow exhibits the characteristics of rain drops having very large effective drop diameters. It is postulated that snow flakes falling below the 0 °C isotherm melt slowly with small water droplets first forming on the outer edges of the flakes; as the snow continues to melt water forms on the surface of the flake, thus it takes on the behaviour of a large rain/ice drop; in the final stages of melting the particles start to collapse into smaller drops. Here another technique for inferring rain-drop sizes4 is described which produces results which, being consistent with those above, support the bright-band model.

On snow crystals of double plate type grown from ice fragments

Seeding experiments were conducted under the condition of water saturation at -15°C temperature by the use of ground ice particles. The diameters of the center circles of double plate snow crystals were smaller than about 25μm. On the other hand, the diameters of irregular center nuclei were larger than about 25μm. Seeding experiments using natural snow crystals were also done for the cases of snow flakes, dendrites and needles. The generation of secondary ice particles was most abundant in the case of dendritic snow flakes. It was also found that needle crystals were fractured in free fall, and the fractions grew to become tall capped snow crystals. According to the observation of snow crystals at the summit of Mt. Teine in Hokkaido, it was noted that ice fragments which floated in the air contributed, to some extent, to the process of multiplying snow crystal growth.

Optical, chemical and physical properties of aerosols over the antarctic ice sheet

Multiwavelength optical measurements of atmospheric extinction and sky brightness in the solar aureole were made at Ross Island and at South Pole Station, Antarctica, to derive the column-integrated size distribution and mass loading of suspended aerosol. In addition, the composition and particle size distribution near the surface at South Pole, the Ross Ice Shelf and from the summit of Mt Erebus volcano were derived by electron microscopic analysis and X-ray spectrometry. The aerosol over the ice sheet has a bimodal size distribution with modal radii in dn/dr at < 0.05 μm and at 0.14 ± 0.02 μm. The number concentration and mass loading for the large mode are 40cm −3 and 300 ng m −3, respectively, while the number concentration of particles in the smaller mode is ~ 10 3 cm −3. The particles over the polar ice sheet are dominated by ammonium sulfate and hydrated droplets of sulfuric acid (60–80% by mass) although trace amounts of oceanic and crustal-derived material have also been detected. Aerosols on the Ross Ice Shelf are relatively large and consist mainly of crustal material, presumably from the exposed land within 20 km distance. Submicron particles collected at the fuming vent of Mt Erebus volcano contained 34% Cl, 22% K and only 18%S. The sulfur aerosol residing over the ice cap shows evidence of being produced by nucleation of trace sulfurbearing gases; the most likely source is organic compounds, possibly CS 2 and COS, released by the oceans. These compounds have long lifetimes (3 and 20, respectively), hence they can be transported to the central polar ice cap and converted to sulfates. It is estimated that downwelling air from the stratosphere is probably not an important source for sulfate particles. The rate of removal of particles to the snow and ice surface of the continentis −300 × 10 −16g cm −2s −1; ninety percent of the removal is by nucleation of snow flakes and ice crystals.

Observations of the Morphology of Melting Snow

Abstract The forms of snow crystals and flakes in various stages of melting can be observed with substantial fidelity after collecting the particles in subfreezing hexane. These forms are largely determined by minimum surface area considerations, which can lead to the breakup of some forms. The collection method might be useful in detailed studies of the radar bright band.

Measurement of Falling Velocity of Snow Using a Laser Doppler Velocimeter

Using a newly deviced laser Doppler velocimeter, measurements of falling velocity of large flakes of snow, powdery snow flakes, sleet and rain in Nagaoka city were made. Measured falling velocities are almost similar to the values reported by other investigators. This method is superior in real time recording to the conventional method using stroboscopic photography. Comparing with the ultrasonic Doppler method, this method is capable of measuring the falling velocity of individual particle because the sampling volume is smaller than the particle size.

Aerosol collection by snow and ice crystals

The scavenging of atmospheric particles was studied by allowing natural snow flakes to fall through a known aerosol, with subsequent recovery of the individual flakes to determine size, shape, and number of particles caught. Five aerosol materials ( B. Subtilis, P1600 pigment, zinc sulfide, polystyrene latex, and anthracene) were used, covering the size range 0.25–3.5 μm. The particulate catch by individual flakes was determined by microscope examination. The observed scavenging efficiencies, E, for the 268 snow flakes exposed and examined was 5.5 × 10 −6–0.38 (0.00055-38%), ignoring the two flakes with zero catch. A related measure, the effective scavenging cross-section, ranged from 1.1 × 10 −6 to 0.020 cm 2. Dimensionless-variable plots of the data indicate that the primary capture mechanism is simple interception. The plot of log E vs log I, where I is the interception parameter, yielded a band of points lying just above the line log E = log3 + logI, which is the theory line for spheres in potential flow. The regression line was log 10 E = 2.477 + 1.366 log 10 I, with correlation coefficient 0.79. No systematic effect due to snow crystal habit could be detected. The data, together with theoretical estimates, indicate that electrostatic scavenging effects were insignificant in the tests. It was established that the chamber scavenging data for particles larger than ~ 0.8 μm is directly applicable to scavenging in the open atmosphere. For smaller particles, this applicability could not be established due to the possibility that thermophoretic forces unrepresentative of the open atmosphere may have been active in the chamber tests. A primitive-variables regression equation was derived. This equation is recommended for prediction purposes.

Christmas Eve On Lonesome

12 Christmas Eve On Lonesome by JOHN FOX, JR. It was Christmas Eve on Lonesome. But nobody on Lonesome knew that it was Christmas Eve, although a child of the outer world could have guessed it, even out in those wilds where Lonesome slipped from one lone log cabin high up the steeps, down through a stretch of jungled darkness to another lone cabin at the mouth of the stream. There was the holy hush in the gray twilight that comes only on Christmas Eve. There were the big flakes of snow that fell as they never fall except on Christmas Eve. There was a snowy man on horseback in a big coat, and with saddlepockets that might have been bursting with toys for children in the little cabin at the head of the stream. But not even he knew that it was Christmas Eve. He was thinking of Christmas Eve, but it was of the Christmas Eve of the year before, when he sat in prison with a hundred other men in stripes, and listened to the chaplain talk of peace and good will to all men upon earth, when he had forgotten all men upon earth but one, and had only hatred in his heart for him. "Vengeance is mine! saith the Lord." That was what the chaplain had thundered at him. And then, as now, he thought of the enemy who had betrayed him to the law, and had sworn away his liberty, and had robbed him of everything in life except a fierce longing for the day when he could strike back and strike to kill. And then, while he looked back hard into the chaplain's eyes, and now, while he splashed through the yellow mud thinking of that Christmas Eve, Buck shook his head; and then, as now, his sullen heart answered: "Mine!" The big flakes drifted to crotch and twig and limb. They gathered on the brim of Buck's slouch hat, filled out the wrinkles in his big coat, whitened his hair and his long mustache, and sifted into the yellow, twisting path that guided his horse's feet. High above he could see through the whirling snow now and then the gleam of a red star. He knew it was the light from his enemy's window; but somehow the chaplain's voice kept ringing in his ears, and every time he saw the light he couldn't help thinking of the story of the Star that the chaplain told that Christmas Eve, and he dropped his eyes by and by, so as not to see it again, and rode on until the light shone in his face. Then he led his horse up a little ravine and hitched it among the snowy holly and rhododendrons, and slipped toward the light. There was a dog somewhere, of course; and like a thief he climbed over the low rail-fence and stole through the tall snow-wet grass until he leaned against an apple-tree with the sill of the window two feet above the level of his eyes. Reaching above him, he caught a stout limb and dragged himself up to a crotch of the tree. A mass of snow slipped softly 13 to the earth. The branch creaked above die light wind; around the comer of the house a dog growled and he sat still. He had waited three long years and he had ridden two hard nights and lain out two cold days in the woods for this. And presently he reached out very carefully , and noiselessly broke leaf and branch and twig until a passage was cleared for his eye and for the point of the pistol that was gripped in his right hand. A woman was just disappearing through the kitchen door, and he peered cautiously and saw nothing but darting shadows. From one comer a shadow loomed suddenly out in human shape. Buck saw the shadowed gesture of an arm, and he cocked his pistol. That shadow was his man, and in a moment he would be in a chair in the chimney comer to smoke his pipe, maybe— his last pipe. Buck smiled — pure hatred...

Jewelweed

ently, and then the puppy crept closer, put his head on his playmate's chest, and the two lay thus asleep. And still Buck looked—his clasp loosening on his pistol and his lips loosening under his stiff mustache—and kept looking until the door opened again and the woman crossed the floor. A flood of light flashed suddenly on the snow, barely touching the snow-hung tips of the appletree , and he saw her in the doorway—saw her look anxiously into the darkness—look and listen a long while. Buck dropped noiselessly to the snow when she closed the door. He wondered what they would think when they saw his tracks in the snow next morning; and then he realized that they would be covered before morning. As he started up the ravine where his horse was he heard the clink of metal down the road and the splash of a horse's hoofs in the soft mud, and he sank down behind a holly-bush. Again the light from the cabin flashed out on the snow. "That you, Jim?" "Yep!" And then the child's voice: "Has oo dot thum tandy?" "Yep!" The cheery answer rang out almost at Buck's ear, and Jim passed death waiting for him behind the bush which his left foot brushed, shaking the snow from the red berries down on the crouching figure beneath. Once only, far down the dark jungled way, with the underlying streak of yellow that was leading him whither, God only knew—once only Buck looked back. There was the red light gleaming faintly through the moonlit flakes of snow. Once more he thought of the Star, and once more the chaplain's voice came back to him. "Mine!" saith the Lord. Just how, Buck could not see with himself in the snow and him back there for life with her and the child, but some strange impulse made him bare his head. "Yourn," said Buck grimly. But nobody on Lonesome—not even Buck—knew that it was Christmas Eve. JEWELWEED cabin on a crooked river high stone hearth floorboards two hands wide forest coming in windows without hangings rough wool blankets pewter and new bread rich evening wine long-fingered hands making strong music Jeanne Kammer 15 ...

A STUDY OF THE TEXTURE OF CHERT IN KUZUU AREA, TOCHIGI PREFECTURE, JAPAN

The Permian and Triassic strata of the Kuzuu area are composed of chert, sandstone, shale and limestone. Chert accounts for 40 per cent of a thick sequence of the strata. Most of the chert are well thin-bedded, and minor portions are ill-bedded and massive. They are various in colors, but are predominantly gray. Under the microscope, textures of quartz in chert may be divided into three forms: microgranular, snow flake and radially fibrous. Snow flake quartz is a aggregate of grains with irregular and indistinct boundaries, and ranges in size from 10 to 30 microns. Bedded chert consists of three forms of quartz, while massive chert consists mostly of microgranular quartz. Electron microscopic observations show that fracture surfaces of chert have three types: novaculite, intermediate and spongy. Comparing the observations of the polarizing and electron microscopes, microgranular texture corresponds to novaculite type. Snow flake and radially fibrous quartz are indistinguishable from each other under the electron microscope, and both show chiefly intermediate type and partly spongy type surfaces. Remains of radiolaria and sponge spicules are composed commonly of clusters of snow flake quartz as well as radially fibrous quartz. Microgranular and snow flake quartz are probably derived from both organic and inorganic silica.

Isotope dilution mass-spectrometry of calcium

Isotope dilution mass-spectrometry can be applied to the determination of minute amounts of calcium in distilled water, deionized water and snow melts from ice sheets in Greenland and Antarctica. The amount of sample required is 20 g for snow analysis. In a 100-ml teflon beaker, 0.3 x 10/sup -7/ M of /sup 12/Ca spike in 0.06 g of dilute nitric acid is accurately weighed. Snow melt is poured directly into the beaker from the agitated sample bottle and is weighed. The mixture is evaporated to 50 mu l in a heated steel tank in which high purity nitrogen gas is streaming. Small drops of the concentrated liquid are loaded onto the tantalum filament by using a quartz micropipette. The ion source used is equipped with a specially designed single filament unit which is heated with accurately controlled electric current. This emits intensive Ca/sup +/ beams from 10/sup -10/ g of calcium salts loaded on the filament. The coefficient of variation for the peak height ratio of /sup 12/Ca to /sup 40/Ca ranges between 0.22 and 0.66% and is not affected by the coexistence of foreign substances. The degree of isotope effects is reduced to a minimum under 1% by runningmore » the mass- spectrometer under common conditions. Calcium and potassium have the isobars with the mass number of 40, but the isobar effects can be reduced to a negligible quantity by baking treatments. Snow melts contain minute amounts of silicate mineral dusts which have played impontant roles as the nucleation center for water vapor at the formation of snow flakes. So it is important that calcium added as a spike is equilibrated isotopically with that in the silicate mineral dusts. If it is not so, calcium isotopes in a salt matrix may be more easily released from the heated filament than those combined with the silicate matrix, and this will result in lower value of calcium. From the content of titanium, calcium from the silicate mineral dusts accounts for nearly 10% of total calcium in snow melts, while the remaining calcium occurs in sea salts predominantly. The concentrations of calclum are found to be 1.9 ppb in both redistilled and deionized water, 2 ppb in snow melts of West Enderby Land, Antarctica, and several ppb in those of Camp Century, Greenland. In Greenland snow strata, calcium concentrates in winter layers as well as dusty components. In both the polar regions, no appreciable variations of calcium concentration have been detected in whole year composite samples since 1750. (auth)« less

Study on Heavy Snowfalls in Kyushu

Recently, also in the warm region Kyushu, which is situated in the south-western area of Japan Islands, a local snowfall has become one of the important meteorological phenomena in winter, since snowfalls have many influences upon agriculture, trasportation, especially in the high-way road which nowadays is going to develop, water resources and so on. The authors have investigated snowfalls by means of the climatological analysis and general synoptic analysis, and had a chance to observe the natural snow crystals and snowflakes associated with the snow clouds developed in the north-west monsoon period, Feb. 5th to 7th in 1969. The snow crystals and flakes were observed with the method of the macroscopic sketch, the replica observation, the close lens camera, and the photographic recording. By those analyses described above it is found that when we have much snow in Kyushu where usually the snowfall occurrence is very rare and its amount is very little, the synoptic conditions and the pattern of snowfall distribution are quite similar to those when the heavy local snowfalls occurred in the coastal regions of Japan Sea. Results of analyses are summarized as follows.1) In large scale synoptic situation, when the cold and dry air mass from the Siberian Continent comes down southward near the northern part of Korean Peninsula and then passes over the Japan Sea, it is modified with heat and vapor from the sea water below and becomes an unstable air mass.2) The occurrence of snowfall is characterized by the strong wind zone near the 850mb level. This corresponds to the strong curvature of wind profile explained previously by Higuchi.3) In meso scale synoptic situation, local lines of convergence appear along the north and south-west coast of Kyushu. Those are made due to the cooling effect of radiation in the inland area and increases in the rate of precipitation.4) Types of Radar Echoes observed support that the snow clouds are convective ones and show their band structure which is characteristic to local heavy snowfalls in Hokuriku and Hokkaido.5) Snowfall distribution shows that much amount of preciptation is seen rather in the lower plain, and this is quite similar to local heavy snowfalls in the coastal region of the Japan Sea.6) Snow crystals observed at Mt. Hiko are almost consistent with the expected ones by Nakaya's Ta-S diagram.

The Six-Cornered Snowflake.

The Six-Cornered Snowflake.

We make an interesting sesquicarbonate of soda called SNOWFLAKE®

We make an interesting sesquicarbonate of soda called SNOWFLAKE®

Snow Crystal Sonde by the use of Shadow Photograph

Snow crystal sonde was designed to know snow shapes, especially, snow flakes and graupel pellets, in the cloud. One snow crystal sonde among 10 was recovered and this result showed that there were a great number of small sized snow particles at about 1000m height in cloud.

Resin Vapour Replication Technique for Snow Crystals and Biological Specimens

SNOW flakes have always been the object of interested observation because of their beauty, simplicity and diversity. A systematic study of them was first undertaken by Bentley, who painstakingly photographed thousands of them in the field1.