Thermal Gradient

A thermal gradient is a spatial variation in temperature across a medium — the directional rate of change that drives heat flow from hot regions to cold regions through conduction, convection, or radiation. It is the fundamental engine of nonequilibrium thermodynamics: without a thermal gradient, there is no spontaneous heat transfer, no entropy production, and no possibility of self-organizing structures such as Bénard cells. The magnitude and geometry of thermal gradients determine not merely how fast heat moves, but what *patterns* emerge in the attempt to dissipate it. To treat a thermal gradient as merely a passive boundary condition is to miss its active role as an organizer of structure.