What Does NLTE Stand For?

NLTE stands for Non Local Thermodynamic Equilibrium

NLTE, or Non Local Thermodynamic Equilibrium, refers to a condition in which the physical properties of a system, such as temperature and density, do not maintain a uniform state across all particles and regions. In NLTE, populations of energy levels are influenced by radiation and interactions that extend beyond local thermal equilibrium, leading to inhomogeneous distributions of particles. This concept is crucial in fields such as astrophysics and atmospheric science, where it helps describe processes in stellar atmospheres and fluctuating environments where local equilibrium assumptions fail to apply.