Some features of manifestations of coronal holes in microwave emission

Using observational data from the SSRT, we have investigated the behavior o f four mid- and low-latitude coronal holes. The coronal holes under study a ppeared as regions of decreased emission intensity relative to the quiet Su n level totally or partially coincident with holes in EUV emission. Differe nce in the electron density and temperature in different holes or different parts of a hole can account for the diversity of manifestations of coronal holes. Estimates showed that the influence of these parameters is stronges t in the wavelength range of 2-5 cm. Depending on particular values of the coronal electron density and temperature, coronal holes are either indistin guishable from the background of the quiet Sun, or show up as regions of de creased or increased microwave emission.