The quiet sun at cm- and mm-wavelengths

The characteristics of the quiet component of solar radiation in the cm and mm wavelength ranges are discussed and interpreted in terms of emission from an inhomogeneous atmosphere. Consideration is given to determinations of the brightness temperature at the center of the solar disk at wavelengths from 1.0 mm to 21 cm, the center-to-limb variation of solar brightness, and the solar radius. It is shown that a two-component model of the solar atmosphere consisting of cool fine structures embedded in a hot plasma can account for the observed brightness variations, however the details of the fine structure at radio wavelengths, which are expected to correspond to the network and cell structure seen in spectral lines, remain to be detected.