sentences:  In atmospheric thermodynamic processes, it is often useful to assume air parcels behave approximately adiabatically, and approximately ideally.The specific gas constant for the standardized mass of one kilogram of a particular gas is variable, and described mathematically as
  
  where formula_3 is the molar gas constant, and formula_4 is the apparent molar mass of gas formula_5 in kilograms per mole.The apparent molar mass of a theoretical moist parcel in Earth's atmosphere can be defined in components of water vapor and dry air as
  
  with formula_7 being partial pressure of water, formula_8 dry air pressure, and formula_9 and formula_10 representing the molar masses of water vapor and dry air respectively.