| Abstract : | To understand the structuring and dynamics of the upper photosphere and the chromosphere of the Sun, we need numerical radiation-magnetohydrodynamical (MHD) simulations. In the solar chromosphere, radiative energy transport is dominated by only the strongest spectral lines. For these lines, the approximation of local thermo-dynamic equilibrium (LTE) is known to be very inaccurate, and a state of equilibrium cannot be assumed in general. To calculate the radiative energy transport under these conditions, the population evolution equation must be evaluated including all time dependent terms. In this talk I will present a review on this topic of research. |
