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We study the Ca II K, H, and λ 849.8 nm line profiles in two regions of the quiet Sun, one being located in the extensive low-latitude coronal hole observed on 3 through 5 August 2003, and the other being located outside the coronal hole. Comparison of the profiles was carried out separately for cells and cell boundaries of the chromospheric network. Our principal result is that space-and time-averaged profiles of the central self-reversal in the coronal hole sites differ from those outside of the hole: Intensities of the K 3 and H 3 central depressions are increased in the cells but are unchanged in the network; the height of the K 2 peaks is reduced in the cells and particularly in the network; the central self-reversal asymmetry is intensified in the network. Distinctions appear at a high confidence level. Line wings as well as average characteristics of the infrared line remain practically unchanged. We discuss probable causes for this behavior of the lower chromosphere lines.

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The equivalent widths of six weak lines ( 7 Li I, Si I, Fe I (two lines), Ti I, and CN) at the equatorial and polar limbs are compared. The lithium line is of greatest interest, because the abundance of lithium isotopes on the Sun and stars is closely related to primordial nucleosynthesis and plasma mixing in their interiors. For four of the six lines, the equivalent widths near the equator have been found to differ from those near the pole at a significance level of at least 95%. The ratios of the equivalent widths at the pole and the equator for the Si I and Fe I lines are consistent with the predictions of the elementary theory of the curves of growth for weak photospheric lines and lead to an estimate of the temperature difference ∼13 K. The Li I and Ti I lines deviate significantly from the predictions made on the basis of static planeparallel, 1D models under local thermodynamic equilibrium (LTE) conditions. The greatest (among the lines being studied) difference between the equivalent widths (≈4%) found for Li I, the only one obtained essentially at a significance level of ∼100%, could be interpreted as one of the numerous manifestations of granulation dynamics. However, the current status of 3D NLTE simulations for the photosphere does not yet allow the ultimate conclusions to be reached. It may well be that at least part of the observed decrease in the equivalent width of the lithium resonance line at the solar pole is attributable to more efficient lithium depletion in the polar regions.

We have carried out calculations, showing how the thermodynamical structure ef the sunspot umbra atmosphere varies during two stages of the oscillatory process of "umbral flashes".