Constants

Constants#

Physical, mathematical, computational, isotope, and material constants.

Defines the following constants:

Mathematical: Pi, Pi2, Pi3, TwoPi, Sqrt2, pi, pi2, pi3, Twopi
Physical: Gravity, T0, P0, T25, sigma, R, R_air, R_H2O, Na, REarth
Isotope: R13VPDB, R18VSMOW, R2VSMOW
Computational: tiny, huge, eps
Material: mmol_co2, mmol_h2o, mmol_air, density_quartz, cheat_quartz, cheat_water, cheat_air, latentheat_vaporization

This module was written by Matthias Cuntz while at Department of Computational Hydrosystems, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany, and continued while at Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Nancy, France.

copyright:: Copyright 2012-2021 Matthias Cuntz, see AUTHORS.rst for details.
license:: MIT License, see LICENSE for details.

Constants:

`Pi`	Mathematical constant \(\pi\)
`Pi2`	Mathematical constant \(\pi/2\)
`Pi3`	Mathematical constant \(\pi/3\)
`TwoPi`	Mathematical constant \(2\pi\)
`pi`	Mathematical constant \(\pi\)
`pi2`	Mathematical constant \(\pi/2\)
`pi3`	Mathematical constant \(\pi/3\)
`Twopi`	Mathematical constant \(2\pi\)
`Sqrt2`	Mathematical constant \(\sqrt{2}\)
`sqrt2`	Mathematical constant \(\sqrt{2}\)
`gravity`	Standard average Earth's gravity (\(m^2 s^{-1}\))
`T0`	0 degree Celsius in Kelvin.
`P0`	Standard pressure (Pa)
`T25`	Standard ambient temperature of 25 \(^\circ C\) in Kelvin [K]
`sigma`	Stefan-Boltzmann constant (\(W m^{-2} K^{-4}\))
`R`	Ideal gas constant R = Na*kB (\(J K^{-1} mol^{-1}\))
`Rair`	Specific gas constant of dry air Rair = R/molmass_air (\(J K^{-1} kg^{-1}\))
`Rh2o`	Gas constant of water vapour Rh2o = R/molmass_h2o (\(J K^{-1} kg^{-1}\))
`Na`	Avogadro number (\(mol^{-1}\))
`kB`	Boltzmann constant (\(J K^{-1}\))
`REarth`	Radius of the Earth (m)
`mmol_co2`	Molar mass of \(CO_2\) (\(g mol^{-1}\))
`molmass_co2`	Molar mass of \(CO_2\) (\(kg mol^{-1}\))
`mmol_h2o`	Molar mass of water (\(g mol^{-1}\))
`molmass_h2o`	Molar mass of water (\(kg mol^{-1}\))
`mmol_air`	Molar mass of dry air of standard atmosphere (\(g mol^{-1}\))
`molmass_air`	Molar mass of dry air (\(kg mol^{-1}\))
`density_quartz`	Density of quartz (\(g cm^{-3}\))
`cheat_quartz`	Heat capacity of quartz (\(J kg^-1 K^-1\))
`cheat_water`	Heat capacity of water (\(J kg^{-1} K^{-1}\))
`cheat_air`	Heat capacity of air (\(J kg^{-1} K^{-1}\))
`latentheat_vaporization`	Latent heat of vaporization of water (\(J kg^{-1}\))
`R13VPDB`	\(^{13}C\) isotope ratio of VPDB
`R18VSMOW`	\(^{18}O\) isotope ratio of VSMOW
`R2VSMOW`	Deuterium= \(^{2}H\) isotope ratio of VSMOW
`tiny`	The smallest positive floating point number with full precision.
`huge`	The largest representable floating point number.
`eps`	Numerical precision of floats.

History

Written Jan 2012 by Matthias Cuntz (mc (at) macu (dot) de)
Ported to Python 3, Feb 2013, Matthias Cuntz
Added dielectric constant for water, Mar 2014, Arndt Piayda
Added heat capacities for air, water and quartz as well as density of quartz, Sep 2014, Arndt Piayda
Added Pi3=pi/3, R13VPDB, R18VSMOW, R2VSMOW, Mar 2015, Matthias Cuntz
Renamed heat capacities, molar masses, density of quartz, Mar 2015, Matthias Cuntz
Moved calculation of dielectric constant of water to own routine, Mar 2015, Matthias Cuntz
Added computational constants such as tiny=np.finfo(np.float).tiny, Nov 2016, Matthias Cuntz
Added gas constants for dry air and water, May 2017, RL
Using numpy docstring format, May 2020, Matthias Cuntz
Added lowercase version of pi constants, May 2020, Matthias Cuntz
Updated all constants related to gases for redefinition of SI units of 2019, Jan 2023, Matthias Cuntz
Renamed some constant for greater consistency, Jan 2023, Matthias Cuntz

Na = 6.02214076e+23#: Avogadro number (\(mol^{-1}\))

P0 = 101325.0#: Standard pressure (Pa)

Pi = 3.141592653589793#: Mathematical constant \(\pi\)

Pi2 = 1.5707963267948966#: Mathematical constant \(\pi/2\)

Pi3 = 1.0471975511965979#: Mathematical constant \(\pi/3\)

R = 8.31446261815324#: Ideal gas constant R = Na*kB (\(J K^{-1} mol^{-1}\))

R13VPDB = 0.0112372#: \(^{13}C\) isotope ratio of VPDB

R18VSMOW = 0.0020052#: \(^{18}O\) isotope ratio of VSMOW

R2VSMOW = 0.00015576#: Deuterium= \(^{2}H\) isotope ratio of VSMOW

REarth = 6371009.0#: Radius of the Earth (m)

Rair = 287.05799595894405#: Specific gas constant of dry air Rair = R/molmass_air (\(J K^{-1} kg^{-1}\))

Rh2o = 461.52280831345604#: Gas constant of water vapour Rh2o = R/molmass_h2o (\(J K^{-1} kg^{-1}\))

Sqrt2 = 1.4142135623730951#: Mathematical constant \(\sqrt{2}\)

T0 = 273.15#: 0 degree Celsius in Kelvin. Conversion constant from Celsius to Kelvin.

T25 = 298.15#: Standard ambient temperature of 25 \(^\circ C\) in Kelvin [K]

TwoPi = 6.283185307179586#: Mathematical constant \(2\pi\)

Twopi = 6.283185307179586#: Mathematical constant \(2\pi\)

cheat_air = 1010.0#: Heat capacity of air (\(J kg^{-1} K^{-1}\))

cheat_quartz = 800.0#: Heat capacity of quartz (\(J kg^-1 K^-1\))

cheat_water = 4180.0#: Heat capacity of water (\(J kg^{-1} K^{-1}\))

density_quartz = 2.65#: Density of quartz (\(g cm^{-3}\))

eps = np.float64(2.220446049250313e-16)#: Numerical precision of floats. The difference between 1.0 and the next smallest representable float larger than 1.0. For example, for 64-bit binary floats in the IEEE-754 standard, \(eps = 2^{-52}\), approximately 2.22e-16.

gravity = 9.80665#: Standard average Earth’s gravity (\(m^2 s^{-1}\))

huge = np.float64(1.7976931348623157e+308)#: The largest representable floating point number.

latentheat_vaporization = 2450000.0#: Latent heat of vaporization of water (\(J kg^{-1}\))

mmol_air = 28.9644#: Molar mass of dry air of standard atmosphere (\(g mol^{-1}\))

mmol_co2 = 44.009#: Molar mass of \(CO_2\) (\(g mol^{-1}\))

mmol_h2o = 18.01528#: Molar mass of water (\(g mol^{-1}\))

molmass_air = 0.0289644#: Molar mass of dry air (\(kg mol^{-1}\))

molmass_co2 = 0.044009#: Molar mass of \(CO_2\) (\(kg mol^{-1}\))

molmass_h2o = 0.01801528#: Molar mass of water (\(kg mol^{-1}\))

pi = 3.141592653589793#: Mathematical constant \(\pi\)

pi2 = 1.5707963267948966#: Mathematical constant \(\pi/2\)

pi3 = 1.0471975511965979#: Mathematical constant \(\pi/3\)

sigma = 5.67e-08#: Stefan-Boltzmann constant (\(W m^{-2} K^{-4}\))

sqrt2 = 1.4142135623730951#: Mathematical constant \(\sqrt{2}\)

tiny = np.float64(2.2250738585072014e-308)#: The smallest positive floating point number with full precision.

Constants

Contents

Constants#