## thermal diffusivity

(

*Also called*heat conductivity, thermometric conductivity.) The ratio of the thermal conductivity*k*of a substance to the product of its specific heat*c*and its density ρ:For a gas, At a temperature of 0°C, the thermal diffusivity for air is 1.9 x 10

*c*is the specific heat at constant pressure,*c*_{p}. The thermal diffusivity determines the rate of heating given the temperature distribution according to an equation, which for one spatial dimension is^{-5}m^{2}s^{-1}. At other temperatures, the ratio μ/*K*is nearly constant, where μ is the dynamic viscosity.*See also*diffusivity, kinematic viscosity.List, R. J. 1951. Smithsonian Meteorological Tables. 6th rev. ed., . 394–395.