# Constants
Weather has many built-in constants that can be used in calculations.

## Constants
- **Kelvin constant**: 273.15 (`_kelvin_`)
- **Pi constant**: 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679 (`_pi_`)
- **Gas constant for dry air**: 287.05 J/(kg·K) (`_rd_`)
- **Specific heat capacity of air at constant pressure**: 1005 J/(kg·K) (`_cp_`)
- **Standard atmospheric pressure**: 101325 Pa (`_p0_`)
- **Latent heat of vaporization for water**: 2260000 J/kg (`_lv_`)
- **Specific heat capacity of water**: 4184 J/(kg·K) (`_cw_`)
- **Density of air**: 1.2 kg/m³ (`_rho_air_`)
- **Density of water**: 1000 kg/m³ (`_rho_water_`)
- **Acceleration due to gravity**: 9.81 m/s² (`_g_`)