Recent thermal models of the chromosphere

The paper describes recent research on the calculation of solar chromospheric models. The models included here are based on the observed spectrum, and on the assumption of hydrostatic equilibrium. The calculations depend on realistic solutions of the radiative transfer and statistical equilibrium equations for optically thick lines and continua, and on including the effects of large numbers of lines throughout the spectrum. Although spectroheliograms show that the structure of the chromosphere is highly complex, one-dimensional models of particular features are reasonably successful in matching observed spectra. There has been considerable recent progress in applying such models to the interpretation of chromospheric observations. 65 references