Snow flakes

The 6180 in Byrd core melted ice as a function of depth has been measured by mass spectrometry [4,5]. Since the 6180 scale depends on the temperature of the ocean water that developed into snow flakes [6], accurate dating of the core itself is necessary to reveal the temperature history of the ocean surface water. Oeschger et al., [7] measured the 14C contents of C02 extracted from 3 tons of ice melted i n situ, at depths of 100, 175, 270, and 380 m near the Byrd site, their 14C ages for 270- and 380-m depths are 1300 700 and 3000 500 years, respectively. 

The interplay of these two basic rates determines the size of the resulting particles. For instance, the reason that snow flakes reach sizes of several cm at lower latitudes but arrive as extremely small crystals, called diamond dust in Antarctica, is that the nuclei that are formed in a cloud, will grow during their voyage to earth by adsorbing water molecules. Obviously, this growth will be more important in the moist atmosphere at low latitudes than in the extremely dry atmosphere above Antarctica. The same interplay of nucleation and growth determine the size of metal particles that are formed on a support by chemical reduction of adsorbed precursors, such as metal ions. Here... 

Fig. 44. Dark field image of an silicon nitride material with snow flakes ...

Fe impurities may cause snow flakes , because of the nucleation and crystallisation of YAG (Y3Al50i2) [532]. The volume change during crystallisation of the grain boundary phase leads to internal stresses which can be cause micropores, or microcracks, or relax by other mechanisms [534, 535]. Such microcracks have only been detected in ceramics with crystallised / -Y2Si207 as grain boundary phase [533]. 

Colouring and snow flakes can be controlled by reducing the interaction of Si3N4 during sintering, and optimising the temperature, time and pressure regime (Sect. 5.3.3). 

Further experiments and model drawings should follow e.g. the observation of the spreading of perfume in a room and the interpretation of the mixture of the continually moving perfume particles and air particles. Or the formation of snow and hoarfrost at winter temperatures below 0°C is interpreted via water particles which form regular pattern in snow flakes they consistently have the six corners, never five or seven (see Sect. 1.6). 

Abstract Despite the absence of translational symmetries, snow flakes and biomacromolecules... 

Everybody agrees that snow flakes are normal crystals of which the macroscopic forms are based on lattice periodicity at an atomic level. Like any other crystal... 

Figure 11-1. Facet-like snow flake from Bentley Humphreys (1931, 1962) Snow Crystals (courtesy...

Figure 11-2. Dendritic snow flake from Bentley Humphreys (courtesy Dover) with hexagonal growth lattice points. The transition from a facet-like growth of the central region to a dendritic growth corresponds to a triplication of the lattice parameter (from [12], courtesy lUCr)...

Snow Flake. [Allied-Signal] Sodium ses-quicarbonate. 

Automatic systems for precipitation sampling are usually designed so that it is possible to take dust-free samples. The automatic mechanism of commercially produced systems is focused on opening of the sample containers during rain and closing in the periods without rain. The lid of the system is controlled by a switch sensitive to the very first rain drops or snow flakes. Usually, the conductivity of rain water is utilized which connects two insulated points with opposite electric charges on an inclined and slightly heated plate. 

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