# constants¶

A collection of meteorologically significant constants.

## Earth¶

Name | Symbol | Short Name | Units | Description |

earth_avg_radius | \(R_e\) | Re | \(\text{m}\) | Avg. radius of the Earth |

earth_gravity | \(g\) | g | \(\text{m s}^{-2}\) | Avg. gravity acceleration on Earth |

gravitational_constant | \(G\) | G | \(\text{m}^{3} {kg}^{-1} {s}^{-2}\) | Gravitational constant |

earth_avg_angular_vel | \(\Omega\) | omega | \(\text{rad s}^{-1}\) | Avg. angular velocity of Earth |

earth_sfc_avg_dist_sun | \(d\) | d | \(\text{m}\) | Avg. distance of the Earth from the Sun |

earth_solar_irradiance | \(S\) | S | \(\text{W m}^{-2}\) | Avg. solar irradiance of Earth |

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) |

## Water¶

Name | Symbol | Short Name | Units | Description |

water_molecular_weight | \(M_w\) | Mw | \(\text{g mol}^{-1}\) | Molecular weight of water |

water_gas_constant | \(R_v\) | Rv | \(\text{J (K kg)}^{-1}\) | Gas constant for water vapor |

density_water | \(\rho_l\) | rho_l | \(\text{kg m}^{-3}\) | Nominal density of liquid water at 0C |

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 |

water_heat_vaporization | \(L_v\) | Lv | \(\text{J kg}^{-1}\) | Latent heat of vaporization for liquid water at 0C |

water_heat_fusion | \(L_f\) | Lf | \(\text{J kg}^{-1}\) | Latent heat of fusion for liquid water at 0C |

ice_specific_heat | \(C_{pi}\) | Cp_i | \(\text{J (K kg)}^{-1}\) | Specific heat of ice at 0C |

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 |

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 |