Dry-adiabatic lapse rate

dry-adiabatic lapse rate

1. A process lapse rate of temperature, the rate of decrease of temperature with height of a parcel of dry air lifted by a reversible adiabatic process through an atmosphere in hydrostatic equilibrium.

   
   

   This lapse rate is g/c_pd, where g is gravitational acceleration and c_pd is the specific heat of dry air at constant pressure, approximately 9.8°C km^-1. Potential temperature is constant with height in an atmospheric layer with this lapse rate.

   
   
2. The adiabatic lapse rate of unsaturated air containing water vapor.

   
   

   This differs from definition 1 by the factor

   

   where r_v is the mixing ratio of water vapor and c_pv is the specific heat of water vapor.