The α–β Transition of Nitrogen

International temperature scales define several fixed points, which temperature values are determined with a very high precision. Some of them, which are in a low-temperature range, are called gaseous fixed points because the reference substances under a normal condition -in a room-temperature range -appear in a gaseous state. These reference substances are called by physicists cryocrystals or quantum crystals when occurring in a low temperature in a solid state. The substances play an important role in a standard thermometry. The triple point of argon, oxygen, neon and hydrogen are primary fixed points of the International Temperature Scale of 1990 (ITS-90) [1]. The triple points of nitrogen, methane and carbon dioxide are secondary fixed points of the scale [2]. Also, the solid-solid phase transitions in the cryocrystals are secondary fixed points of the scale. The highest accuracy methods of measurements applied in a standard thermometry enable the determination with a very small uncertainty of the phase transition temperatures, its reproducibility and stability. The reproducibility and stability of the transition temperature are the most important factors deciding about usefulness of these points in thermometry. Using the highest accuracy methods, better than 1 mK, which at present are used in metrology only can give a new information about nature and properties of investigated substances important also for physicists. PACS: 64.60.Ej Studies/theory of phase transitions of specific substances; 64.75.-g Phase equilibria; 67.90.+z Other topics in quantum fluids and solids.

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“…In the low-temperature range, the International [4][5][6][7] and results of the measurements are presented in this paper.…”

Section: Temperature Scalementioning

confidence: 99%

Cryocrystal phase transitions applied as temperature standards

Szmyrka-Grzebyk

Kowal

2009

Low Temperature Physics

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“…This latent heat is equal to 7.7 kJ kg −1 in Lipiński et al (2007), with a discrepancy in the values illustrating the errors (≈ 6 %) made in measurements of properties of cryogenic substances. The latent heat of melting at the triple point (63.1 K) is equal to 25.7 kJ kg −1 in MF97.…”

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confidence: 93%

On the computation of moist‐air specific thermal enthalpy

Marquet

2014

Quart J Royal Meteoro Soc

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The specific thermal enthalpy of a moist-air parcel is defined analytically following a method in which specific moist entropy is derived from the Third Law of thermodynamics. Specific thermal enthalpy is computed by integrating specific heat content with respect to absolute temperature and including the impacts of various latent heats (i.e., solid condensation, sublimation, melting, and evaporation). It is assumed that thermal enthalpies can be set to zero at 0 K for the solid form of the main chemically inactive components of the atmosphere (solid-α oxygen and nitrogen, hexagonal ice). The moist thermal enthalpy is compared to already existing formulations of moist static energy (MSE). It is shown that the differences between thermal enthalpy and the thermal part of MSE may be quite large. This prevents the use of MSE to evaluate the enthalpy budget of a moist atmosphere accurately, a situation that is particularly true when dry-air and cloud parcels mix because of entrainment/detrainment processes along the edges of cloud. Other differences are observed when MSE or moist-air thermal enthalpy is plotted on a psychrometric diagram or when vertical profiles of surface deficit are plotted.

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“…1 and 2. They are based on the books and papers of Fagerstroem and Hallet (1969), Jacobsen et al (1997), Manzhelii and Freiman (1997), Kudryavtsev and Nemchenko (2001), Feistel and Wagner (2006) and Lipiński et al (2007). The Third law means that the entropy of a perfect crystal approaches zero as temperature approaches absolute zero, leading to s(0, p 0 ) = 0.…”

Section: Computation Of Standard Values For Entropies and Enthalpiesmentioning

confidence: 99%

Formulations of moist thermodynamics for atmospheric modelling

Marquet,

Geleyn

2015

Preprint

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The α–β Transition of Nitrogen

Cited by 7 publications

References 11 publications

Cryocrystal phase transitions applied as temperature standards

Cryocrystal phase transitions applied as temperature standards

On the computation of moist‐air specific thermal enthalpy

Formulations of moist thermodynamics for atmospheric modelling

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