Diagnostics of solar chromosphere plasma based on observations of millimeter radiation

Graphical abstract: Observations of the solar chromosphere, the least understood layer of the Sun, at millimeter wavelengths provide new and perspective tests for atmospheric modeling. Comparison of the quiet Sun brightness temperatures observed at millimeter wavelengths with the model spectra calculated from the classical atmospheric models is presented as one of the results. Highlights: ► Classical solar atmospheric models are too warm for observations at mm wavelengths. ► Dynamic models are in agreement with the spatially averaged mm observational data. ► Mm interferometric observations confirm the complex structure of the chromosphere. ► Mm interferometric observations confirm the presence of chromospheric dynamics. - Abstract: In this paper we review the current knowledge of the solar chromosphere from its observations at millimeter wavelengths. We present the observational spectrum of the quiet Sun millimeter wave brightness temperature and its comparison with brightness temperatures computed from the standard static models and the dynamic simulations. Reporting on the findings regarding the structure and dynamics of the solar chromosphere from the best available interferometric data obtained at 3.5 mm we demonstrate a great potential of the mm observations for the study of the solar chromosphere.