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Arden Buck Equation
The Arden Buck equations are a group of empirical correlations that relate the saturation vapor pressure to temperature for moist air. The curve fits have been optimized for more accuracy than the Goff–Gratch equation in the range .Buck 1981 A set of several equations were developed, each of which is applicable in a different situation. Formula The equations suggested by (which are modifications of the equations in ) are: : P_\left(T \right) = 6.1121 \exp \left(\left( 18.678 - \frac \right)\left( \frac \right)\right) , over liquid water, > 0 °C : P_\left(T \right) = 6.1115 \exp \left(\left( 23.036 - \frac \right)\left( \frac \right)\right) , over ice, < 0 °C where: * is the saturation vapor pressure in * is the [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saturation Vapor Pressure
Vapor pressure or equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indication of a liquid's thermodynamic tendency to evaporate. It relates to the balance of particles escaping from the liquid (or solid) in equilibrium with those in a coexisting vapor phase. A substance with a high vapor pressure at normal temperatures is often referred to as '' volatile''. The pressure exhibited by vapor present above a liquid surface is known as vapor pressure. As the temperature of a liquid increases, the attractive interactions between liquid molecules become less significant in comparison to the entropy of those molecules in the gas phase, increasing the vapor pressure. Thus, liquids with strong intermolecular interactions are likely to have smaller vapor pressures, with the reverse true for weaker interactions. The vapor p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vapour Pressure Of Water
The vapor pressure of water is the pressure exerted by molecules of water vapor in gaseous form (whether pure or in a mixture with other gases such as air). The saturation vapor pressure is the pressure at which water vapor is in thermodynamic equilibrium with its condensed state. At pressures higher than saturation vapor pressure, water will condense, while at lower pressures it will evaporate or sublimate. The saturation vapor pressure of water increases with increasing temperature and can be determined with the Clausius–Clapeyron relation. The boiling point of water is the temperature at which the saturated vapor pressure equals the ambient pressure. Water supercooled below its normal freezing point has a higher vapor pressure than that of ice at the same temperature and is, thus, unstable. Calculations of the (saturation) vapor pressure of water are commonly used in meteorology. The temperature-vapor pressure relation inversely describes the relation between the boilin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goff–Gratch Equation
The Goff–Gratch equation is one (arguably the first reliable in history) amongst many experimental correlation proposed to estimate the saturation water vapor pressure at a given temperature. Another similar equation based on more recent data is the Arden Buck equation. Historical note This equation is named after the authors of the original scientific article who described how to calculate the saturation water vapor pressure above a flat free water surface as a function of temperature (Goff and Gratch, 1946). Goff (1957) later revised his formula, and the latter was recommended for use by the World Meteorological Organization in 1988, with further corrections in 2000. The current 2015 edition of the WMO Technical Regulations (WMO-No. 49) however states in Volume 1, Part III, Section 1.2.1, that any formula or constant given in the Guide to Meteorological Instruments and Methods of Observation a.k.a. CIMO-Guide (WMO-No. 8) shall be used, and this document only contains the muc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pascal (unit)
The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is an SI coherent derived unit defined as one newton per square metre (N/m2). It is also equivalent to 10 barye (10 Ba) in the CGS system. Common multiple units of the pascal are the hectopascal (1 hPa = 100 Pa), which is equal to one millibar, and the kilopascal (1 kPa = 1000 Pa), which is equal to one centibar. The unit of measurement called '' standard atmosphere (atm)'' is defined as . Meteorological observations typically report atmospheric pressure in hectopascals per the recommendation of the World Meteorological Organization, thus a standard atmosphere (atm) or typical sea-level air pressure is about 1013 hPa. Reports in the United States typically use inches of mercury or millibars (hectopascals). In Cana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antoine Equation
The Antoine equation is a class of semi-empirical correlations describing the relation between vapor pressure and temperature for pure substances. The Antoine equation is derived from the Clausius–Clapeyron relation. The equation was presented in 1888 by the French engineer (1825–1897). Equation The Antoine equation is \log_ p = A - \frac, where is the vapor pressure, is temperature (in °C or in K according to the value of ), and , and are component-specific constants. The simplified form with set to zero, \log_ p = A - \frac, is the August equation, after the German physicist Ernst Ferdinand August (1795–1870). The August equation describes a linear relation between the logarithm of the pressure and the reciprocal temperature. This assumes a temperature-independent heat of vaporization. The Antoine equation allows an improved, but still inexact description of the change of the heat of vaporization with the temperature. The Antoine equation can also be tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetens Equation
Tetens may refer to: People * Alfred Tetens (1835-1903), German explorer * Axel Tetens (1892–1961), Danish Olympic wrestler * Johannes Nikolaus Tetens (1736–1807), German-Danish philosopher and scientist * Otto Tetens (1865–1945), German scientist * T.H. Tetens (1899-1976), Jewish German journalist Other uses * Tetens equation, calculates the saturation vapor pressure of water over liquid and ice See also * Teten {{surname ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lee–Kesler Method
The Lee–Kesler method allows the estimation of the saturated vapor pressure at a given temperature for all components for which the critical pressure ''P''c, the critical temperature ''T''c, and the acentric factor ''ω'' are known. Equations : \ln P_ = f^ + \omega \cdot f^ : f^=5.92714 - \frac - 1.28862 \cdot \ln T_ + 0.169347 \cdot T_^6 : f^=15.2518 - \frac-13.4721 \cdot \ln T_ + 0.43577 \cdot T_^6 with :P_=\frac ( reduced pressure) and T_=\frac ( reduced temperature). Typical errors The prediction error can be up to 10% for polar components and small pressures and the calculated pressure is typically too low. For pressures above 1 bar, that means, above the normal boiling point, the typical errors are below 2%. Example calculation For benzene with * ''T''c = 562.12 KBrunner E., Thies M.C., Schneider G.M., ''J.Supercrit. Fluids'', 39(2), 160–173, 2006 * ''P''c = 4898 kPa * ''T''b = 353.15 K * ''ω'' = 0.2120 Dortmund Data Bank the following calculati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Thermodynamics
Atmospheric thermodynamics is the study of heat-to-Work (physics), work transformations (and their reverse) that take place in the Earth's atmosphere and manifest as weather or climate. Atmospheric thermodynamics use the laws of classical thermodynamics, to describe and explain such phenomena as the properties of moist air, the formation of clouds, atmospheric convection, boundary layer meteorology, and vertical instabilities in the atmosphere. Atmospheric thermodynamic diagrams are used as tools in the forecasting of storm development. Atmospheric thermodynamics forms a basis for cloud microphysics and convection parametrization (climate), parameterizations used in numerical weather models and is used in many climate considerations, including convective-equilibrium climate models. Overview The atmosphere is an example of a non-equilibrium system. Atmospheric thermodynamics describes the effect of buoyant forces that cause the rise of less dense (warmer) air, the descent of more d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
