Constants (metpy.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 |
\(\text{kg}\) |
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 |
\(\text{J (K kg)}^{-1}\) |
|
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 |
\(C_{pl}\) |
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] |
water_heat_sublimation |
\(L_s\) |
Ls |
\(\text{J kg}^{-1}\) |
Latent heat of sublimation for water, Lv + Lf |
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 |
water_triple_point_temperature |
\(T_0\) |
T0 |
\(\text{K}\) |
Triple-point temperature of water [2] |
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 |