Kinetic temperature
= Kinetic temperature
{title2=$T_k$}
For an isotropic nonrelativistic Maxwellian particle population, <kinetic temperature> describes random translational motion, with mean kinetic energy $3k_BT_k/2$ per particle after subtracting bulk motion. Different species can have different kinetic temperatures outside thermal equilibrium. A rotational excitation temperature equals the kinetic temperature only when the excitation is sufficiently thermalized; a radiation brightness temperature is another distinct quantity.