# constants¶

A collection of meteorologically significant constant and thermophysical property values.

## Earth¶

 Name Symbol Short Name Units Description earth_avg_radius $$R_e$$ Re $$\text{m}$$ Avg. radius of the Earth 1 earth_gravity $$g$$ g $$\text{m s}^{-2}$$ Avg. gravity acceleration on Earth 2 gravitational_constant $$G$$ G $$\text{m}^{3} {kg}^{-1} {s}^{-2}$$ Gravitational constant 2 earth_avg_angular_vel $$\Omega$$ omega $$\text{rad s}^{-1}$$ Avg. angular velocity of Earth 1 earth_sfc_avg_dist_sun $$d$$ d $$\text{m}$$ Avg. distance of the Earth from the Sun 3 earth_solar_irradiance $$S$$ S $$\text{W m}^{-2}$$ Avg. solar irradiance of Earth 4 earth_max_declination $$\delta$$ delta $$\text{degrees}$$ Max. solar declination angle of Earth earth_orbit_eccentricity $$e$$ $$\text{None}$$ Avg. eccentricity of Earth’s orbit earth_mass $$m_e$$ me $$\text{kg}$$ Total mass of the Earth (approx) 1 2

## Water¶

 Name Symbol Short Name Units Description water_molecular_weight $$M_w$$ Mw $$\text{g mol}^{-1}$$ Molecular weight of water 5 water_gas_constant $$R_v$$ Rv $$\text{J (K kg)}^{-1}$$ Gas constant for water vapor 2 5 density_water $$\rho_l$$ rho_l $$\text{kg m}^{-3}$$ Maximum recommended density of liquid water, 0-40C 5 wv_specific_heat_press $$C_{pv}$$ Cp_v $$\text{J (K kg)}^{-1}$$ Specific heat at constant pressure for water vapor wv_specific_heat_vol $$C_{vv}$$ Cv_v $$\text{J (K kg)}^{-1}$$ Specific heat at constant volume for water vapor water_specific_heat $$Cp_l$$ Cp_l $$\text{J (K kg)}^{-1}$$ Specific heat of liquid water at 0C 6 water_heat_vaporization $$L_v$$ Lv $$\text{J kg}^{-1}$$ Latent heat of vaporization for liquid water at 0C 7 water_heat_fusion $$L_f$$ Lf $$\text{J kg}^{-1}$$ Latent heat of fusion for liquid water at 0C 7 ice_specific_heat $$C_{pi}$$ Cp_i $$\text{J (K kg)}^{-1}$$ Specific heat of ice at 0C 7 density_ice $$\rho_i$$ rho_i $$\text{kg m}^{-3}$$ Density of ice at 0C

## Dry Air¶

 Name Symbol Short Name Units Description dry_air_molecular_weight $$M_d$$ Md $$\text{g / mol}$$ Nominal molecular weight of dry air at the surface of th Earth 8 dry_air_gas_constant $$R_d$$ Rd $$\text{J (K kg)}^{-1}$$ Gas constant for dry air at the surface of the Earth dry_air_spec_heat_press $$C_{pd}$$ Cp_d $$\text{J (K kg)}^{-1}$$ Specific heat at constant pressure for dry air dry_air_spec_heat_vol $$C_{vd}$$ Cv_d $$\text{J (K kg)}^{-1}$$ Specific heat at constant volume for dry air dry_air_density_stp $$\rho_d$$ rho_d $$\text{kg m}^{-3}$$ Density of dry air at 0C and 1000mb

## General Meteorology Constants¶

 Name Symbol Short Name Units Description pot_temp_ref_press $$P_0$$ P0 $$\text{Pa}$$ Reference pressure for potential temperature poisson_exponent $$\kappa$$ kappa $$\text{None}$$ Exponent in Poisson’s equation (Rd/Cp_d) dry_adiabatic_lapse_rate $$\gamma_d$$ gamma_d $$\text{K km}^{-1}$$ The dry adiabatic lapse rate molecular_weight_ratio $$\epsilon$$ epsilon $$\text{None}$$ Ratio of molecular weight of water to that of dry air
1(1,2,3)

[Moritz2000]

2(1,2,3,4)

[CODATA2018]

3

[IAU2012]

4

[Kopp2011]

5(1,2,3)

[IAPWS2001]

6

[IAPWS1995]

7(1,2,3)

[WMO1966]

8

[Picard2008]