[en] Very fast vibrations of the solar image during telescopic observations are discussed. It was found that, due to atmospheric heat turbulence, the positions of individual detailed formations in the sunspot umbra in pictures taken over an interval of 2.5 s may differ by as much as 1''. (author)

[en] Processes are investigated accompanying the formation of a very small, secondary active region during the development of its new local magnetic field on the background field through its restructuring and dissipation, as well as during the evolution of a small bipolar sunspot group. The magnetic flux values are estimated. The morphology of small sunspot transformation and two ways of their disintegration are studied. (author)

[en] Processes visible during several impulses of new sunspot formations at the periphery of an older large background magnetic field body in which one rotation earlier the large June-July 1974 proton-flare region developed are discussed. The coalescence of separate nuclei into the future umbra and the counter-clockwise rotation of the whole leading region, the change in the sense of rotation during its further development as well as the non-simultaneous development of individual parts of the active region are pointed out. (author)

[en] All processes are studied visible during the development of the magnetic field, sunspots and chromospheric structures in the usual active region of August 1974. The connection of the active region with the dynamics of the background field is discussed. The formation of a ''centre of magnetic activity'' is demonstrated on magnetic charts as well as in photospheric and chromospheric details. The regularities in the active region's magnetic field topology and dynamics, and their relations to the sunspot group development and formation of individual sunspots are shown. The process is described of formation of a penumbra as a slow, continuous reorganization of granular field areas around the main spot nucleus in strong dependence on the field topology. It may proceed successively around the umbra surrounded by the opposite polarity in the course of several hours, stopping or possibly reversing before it continues its growth. Again it is very difficult to explain the observed field behaviour on a model of emerging flux tubes. (author)

[en] On the basis of high resolution and low scattered light photographs of different sunspots and their umbrae the behaviour of umbral structural details was investigated. The main results are as follows: each sunspot umbra, regardles of its size, magnetic field intensity, darkness, form, age and presence of a penumbra, has an identical internal morphological structure, formed of a dark network of cellular elements, the center of each being filled with a bright grain. Morphologically this structure does not differ from the network of photospheric granules, only the apparent width of the dark intergranular space grows and its darkness deepens with the increasing intensity of the local magnetic field. The constructed structural maps representing the positions of the bright central parts of the cellular elements, are completely identical for both photospheric as well as for umbral granular fields, they show the same surface density of the individual bright element central positions and the same characteristic length scale of bright element distribution of 1.2'' to 1.4''. The character of the internal umbral structure does not change during the whole process of spot development and does not depend on the phase of the solar activity cycle either. In the structural maps, it is impossible to find any indication of sunspot existence. The life-time of the individual umbral cells seems to fall within the interval of 10 to 30 minutes, although certain cellular elements live much longer. During the study, the fundamental physical importance of the dark intergranular space in the photosphere was again emphasized. The question of a more general relationship between the special behaviour of the dark cool intergranular plasma with an imbedded magnetic field was discussed. (author)

[en] The results are presented of a study of sunspot development in colliding magnetic fields of two large active regions forming one complex proton-flare sunspot group. Morphological changes of two types of sunspot light bridges the formation of new sunspots in two main and one secondary ''centre of activity'' which coincide well with the ''magnetic centres'' and the dynamical consequences of motions and collisions of different umbrae of same and opposite polarities are shown. (author)

[en] The results are compared of older spectroscopic magnetic field and velocity field observations in regular sunspots with the results obtained from white-light and monochromatic photographs of sunspots in the form of three schemes of magnetic field lines of force, velocity vectors and fine structure fibril distribution. Schemes in which the horizontal and vertical scales are not distorted show good agreement of the magnotic field distribution in the penumbra with the motion of the photospheric and chromospheric penumbral matter, their depths and heights. The difference is obtained between umbral and penumbral field topology and physical conditions, and the uncertainty a nty ascertained of the position of bright penumbral fibrils in relation to the magnetic field and radial motion distribution. The deductions from this comparison are briefly discussed. (author)

[en] The horizontal magnetic field component distribution calculated at the photospheric level was compared with the penumbral fine structure of the large complex group in McMath active region 13 043 before the white-light flare of July 4, 1974. The magnetic field was calculated in a potential approximation and the shape of the individual spots in the group was taken into account. Good agreement was found in the peripheral portions of the flare activity regions, whereas strong discrepancies appeared in the location of the white-light flare origin and its close neighbourhood. These discrepancies support the idea that the magnetic field structure in these regions before the white-light flare is non-potential at the photospheric level. Part of these discrepancies (non-potentialities) disappear during the following white-light phenomenon, which is probably connected with the current dissipation in the flare. (author)

No abstract available

[en] An attempt is made to demonstrate the suitability of the Ondrejov Observatory for high-quality and high-resolution observations of solar features from all systematic solar observations made at the site since 1948. The climate at Ondrejov, as well as the observational conditions over the years and in different months are discussed. The changes in solar seeing in the course of the day and the intervals of best seeing conditions are shown. Some high-quality photographs of the photosphere are demonstrated as an example of the usefulness of the observational material for obtaining new aspects of solar active regions. (author)