Temperature at a contact surface If two semi-infinite bodies initially at temperatures T_1 and T_2 are brought in perfect thermal contact, the temperature at the contact surface T_m will be a
weighted mean based on their relative effusivities. :U_{dyn}(t) = e\sqrt{\frac{\pi}{4t}} \approx \frac{e}{\sqrt{t}} ; during 0 where e= \frac{\lambda}{\sqrt{\alpha}} and U = \frac{\lambda}{L}.
Planetary science For planetary surfaces,
thermal inertia is a key phenomenon controlling the
diurnal and
seasonal surface temperature variations. The thermal inertia of a
terrestrial planet such as Mars can be approximated from the thermal effusivity of its near-surface geologic materials. In
remote sensing applications, thermal inertia represents a complex combination of particle size, rock abundance, bedrock outcropping and the degree of induration (i.e. thickness and hardness). A rough approximation to thermal inertia is sometimes obtained from the amplitude of the diurnal temperature curve (i.e. maximum minus minimum surface temperature). On Earth, thermal inertia of the global ocean is a major factor influencing
climate inertia. Ocean thermal inertia is much greater than land inertia because of
convective heat transfer, especially through the upper
mixed layer. The thermal effusivities of stagnant and frozen water underestimate the vast thermal inertia of the dynamic and multi-layered ocean.
Thermographic inspection Thermographic inspection encompasses a variety of
nondestructive testing methods that utilize the transient characteristics of heat propagation through a transfer medium. These methods include
Pulse-echo thermography and
thermal wave imaging, which utilize mixtures of heat diffusion and infrared
em wave transport. Thermal effusivity and diffusivity of the materials being inspected can serve to simplify the mathematical modelling of, and thus interpretation of results from these techniques. == Measurement interpretation ==