Snow crystals

Snow crystals [4] Their macroscopic structure is different from a bulk three-dimensional ice crystal, but they are formed by homologous pair-pair interaction between water molecules and are static and in thermodynamic equilibrium. It should be noted, however, that dendritic crystal growth is a common phenomenon for metals [5-7] and polymers. The crystals grow under non-equilibrium conditions, but the final crystal is static. 

Atmospheric trace gas chemistry is a new rapidly growing field of paleo-atmospheric research, because the radiative properties of CO2, CH4, and N2O make them potential indicators of climate change. A fundamental problem in constructing a record of trace gas concentrations from ice-cores is the fact that the air in bubbles is always younger than the age of the surrounding ice. This is because as snow is buried by later snowfalls and slowly becomes transformed to fim and ice, the air between the snow crystals remains in contact with the atmosphere until the air bubbles become sealed at the fim/ice transition, when density increases to about 0.83gcm. The trapped air is thus younger than the matrix, with the age difference... 

Are you ready for the answer Here is the list of terms sorted in order of beauty as determined by my little survey of scientists and colleagues. The numbers in parentheses indicate the number of times the term was an individual s first choice dancing flames (31), snow crystal (20), mist-covered swamp (17), spiral nautilus shell (10), mossy cavern (5), kaleidoscope image (5), avalanche (4), computer chip (3), seagull s cry (3), tears on a little girl (3), trilobite fossil (2), glimmer of mercury (2), wine (2), asphalt (1). 

Brad P. comments, Both the compnter chip and snow crystal are beantifnl because of their complexity, order and diversity—all within a small package. Both say volumes about the beauty and intelligence of their creators. ... 

If each cage region were to contain a single snow crystal, what size lattice would you need to hold the number of snow crystals necessary to form the ice age, which has been estimated to be 10 ° crystals If you were to draw... 

Figure 2.1. Various forms exhibited by crystals, (a) Polyhedral crystals (b) hopper crystal (c) dendritic crystal (snow crystal, photographed by the late T. Kobayashi) (d) step pattern observed on a hematite crystal (0001) face (e) internal texture of a single crystal (diamond-cut stone, X-ray topograph taken by T.Yasuda) (f) synthetic single crystal boule. Si grown by the Czochralski method (g) synthetic corundum grown by the Verneuil method.

Figure 3.23. Morphodrom of snow crystals Nakaya s diagram [22].

U. Nakaya, Snow Crystals, Natural and Artificial, Cambridge, Mass., Harvard University Press, 1954... 

As can be seen in the Nakaya diagram in Fig. 3.23, snow crystals grown in a reduced vapor supply (smaller driving force) appear as polyhedral crystals... 

Figure 4.10. Kuroda s model explaining the repeated Habitus change of snow crystals [23]. Shaded areas are crystals dotted areas are QLLs (quasi-liquid layers).

Crystals are solid materials having regular atomic arrangements characterized by periodicity and anisotropy. These properties are universally present, irrespective of whether the crystal is inorganic or organic, in living systems or in the inanimate world. Crystals exhibit various external forms, as represented by the elaborately varied dendritic forms of snow crystals or the hexagonal prismatic forms of rock-crystal. This variety of shape has stimulated scientific curiosity since the seventeenth century, since when intensive efforts have been made to understand the reasons why and how crystals can take a variety of forms. 

Every mineral is a product of the redistribution or recombination of its component chemical elements to form a stable substance. The process is known as crystal I izution. The process may involve precipitation of chemical elements from aqueous solutions at the earth s surface, ui from siliceous melts imagmas) from the earth s interior. In either situation, the process is dependent upon the degree of concentration of the constituent chemical elements present and the temperaturc/pressure conditions. Preeipilalion from vapor also is possible. An example is the hot vapor, rich in sulfur dioxide, which is emitted from vents associated with volcanoes. Upon becoming exposed to Ihe cooler atmosphere, crystal sulfur is deposited around those vents. Snow crystals arc another example of precipitation from vapor. 

LaChapelle E. Field Guide to Snow Crystals. Seattle University of Washington Press, 1969. 

The type of wax used is decided by the team s wax technicians. It is their job to inspect the snow at all major competition sites. They look at the snow crystals under microscopes to determine their size and humidity. Although the snow on downhill and cross-country courses can look smooth on television, under a microscope, snow is seen to consist of crystals that have rough edges with varying water contents. The technicians create mixtures of different waxes and add other closely guarded secret ingredients that they test under different racing weather and snow conditions. 

One of the most beautiful and most common examples of this symmetry is the m-6 m symmetry of snow crystals. The virtually endless variety of their shapes and their natural beauty make them outstanding examples of symmetry. The fascination in the shape and symmetry of snowflakes goes far beyond the scientific interest in their formation, variety, and properties. The morphology of the snowflakes is determined by their internal structures and the external conditions of their formation. The mechanism of snowflake formation has been the subject of considerable research efforts. It is well known that... 

The coldness and lifelessness of too much symmetry is as beautifully expressed by Thomas Mann as the beauty of the hexagonal symmetry of the snow crystal. Michael Polanyi remarked that an environment that was perfectly ordered was not a suitable human habitat [19], Crystallographers Fedorov and Bernal simply stated Crystallization is death [20],... 

There are two fundamental books—collections of snowflake pictures—available today as a result of photomicrography. W. A. Bentley devoted his lifetime to taking photomicrographs of snow crystals and collected at least 6000 of them, and about half of them appeared in his book co-authored with W. J. Humphreys [30], This most well-known book on snowflakes is probably unsurpassable. Bentley s photomicrographs have been reproduced innumerable times in various places—sometimes without indicating the source. Some... 

Figure 2-24. Snow crystals by Descartes from 1635 after Nakaya [28],...

Nakaya made important contributions not only to observing the perfect or near perfect symmetries of the snow crystals but also the... 

Figure 2-27. From Nakaya s general classification of snow crystals [33].

W. A. Bentley, W. J. Humphreys, Snow Crystals. McGraw-Hill, New York and London, 1931. 

J. Needham, Lu Gwei-Djen, The Earliest Snow Crystal Observations. Weather 1961, 16, 319-327. 

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