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We have studied Ca II K line profiles, using two time series of spectrograms taken in two regions near the solar disk center. In each of the regions, the spectrograph slit cut out several areas of the quiet region and a plage. For the selected chromospheric structures, we have derived K line profiles and have defined a number of parameters that characterize the spatial and temporal variations of the profiles. The analysis of profile shapes in different structures belonging to the same moment of time has shown that there are structures whose profiles differ only slightly from each other in the photosphere, but differ dramatically in the chromosphere. The structures begin to differ from the level of formation of K1 and continue to differ further in the chromosphere. There are, however, structures which begin to differ at the level of the photosphere and continue to differ in the chromosphere. The difference between profile shapes in different structures is likely to be associated both with different thermodynamic conditions and with different magnetic field topology at a given point at a given time. We have examined temporal variations of the Ca II K line profiles in structural chromospheric elements, which are caused by the process of K2v grains. In most of the studied areas of the chromospheric structures, the brightening of the K2v peak develops according to the “common” scenario: at the time of maximum brightness, the line shifts toward the red side. There are, however, cases when the brightening of the K2v peak occurs with a shift of the line to the violet side or with no shift at all. We have constructed scatter plots for some pairs of profile parameters related to intensities at characteristic points of the profile and their shifts. A correlation has been found between intensities in the center and wings of the K line. The correlation between shifts of the K2v and K2r peaks is very weak or completely absent.

Spatial and temporal variations of K Ca II line profile shapes in different structures of the solar chromosphere. I. Features of individual profiles