Heat capacity ratio
In thermal physics and thermodynamics, the heat capacity ratio or adiabatic index or ratio of specific heats or Poisson constant, is the ratio of the heat capacity at constant pressure () to heat capacity at constant volume (
). It is sometimes also known as the isentropic expansion factor and is denoted by
(gamma)(for ideal gas) or
(kappa)(isentropic exponent, for real gas). The symbol gamma is used by aerospace and chemical engineers. Mechanical engineers use the Roman letter
.