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The saturation with respect to water cannot be measured much below –50 °C, so manufacturers should use one of the following expressions for calculating saturation vapour pressure relative to water at the lowest temperatures – Wexler (1976, 1977), [1] [2] reported by Flatau et al. (1992)., [3] Hyland and Wexler (1983) or Sonntag (1994 ...
The Tetens equation is an equation to calculate the saturation vapour pressure of water over liquid and ice. It is named after its creator, O. Tetens who was an early German meteorologist. It is named after its creator, O. Tetens who was an early German meteorologist.
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.
An ISO standard, "Soil quality — Determination of pore water pressure — Tensiometer method", ISO 11276:1995, "describes methods for the determination of pore water pressure (point measurements) in unsaturated and saturated soil using tensiometers. Applicable for in situ measurements in the field and, e. g. soil cores, used in experimental ...
Water retention curve is the relationship between the water content, θ, and the soil water potential, ψ. The soil moisture curve is characteristic for different types of soil, and is also called the soil moisture characteristic. It is used to predict the soil water storage, water supply to the plants (field capacity) and soil aggregate stability.
By this definition, a saturated liquid has q = 0. A saturated vapor has q = 1. [3] An alternative definition is the 'equilibrium thermodynamic quality'. It can be used only for single-component mixtures (e.g. water with steam), and can take values < 0 (for sub-cooled fluids) and > 1 (for super-heated vapors):
In petroleum engineering, the Leverett J-function is a dimensionless function of water saturation describing the capillary pressure, [1] = / where is the water saturation measured as a fraction, is the capillary pressure (in pascal), is the permeability (measured in m²), is the porosity (0-1), is the surface tension (in N/m) and is the contact angle.
The relative activity of a species i, denoted a i, is defined [4] [5] as: = where μ i is the (molar) chemical potential of the species i under the conditions of interest, μ o i is the (molar) chemical potential of that species under some defined set of standard conditions, R is the gas constant, T is the thermodynamic temperature and e is the exponential constant.