Thermal lag

Thermal lag describes a body's temperature with respect to time as a result of its thermal mass. A body with high thermal mass (high heat capacity and low conductivity) will have a large thermal lag.

${\displaystyle {\text{Thermal Lag}}(s)={L \over {\sqrt {2\alpha \Omega }}}}$

where ${\displaystyle \alpha }$ is the thermal diffusivity of the material (m²s⁻¹), ${\displaystyle \Omega }$ is the external angular frequency (s⁻¹), and ${\displaystyle L}$ is the thickness (m).