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This article presents a survey of studies incorporating methods of evaluation of Greenwich observations. It also describes some extreme sunspot groups (i.e., groups with a very large area, a very long life, and/or in very high heliographic latitudes); data on the total areas of the largest sunspots are given, and a survey of the parameters concerning individual 11-year cycles, resulting from Greenwich Photoheliographic Results, is presented. [ABSTRACT FROM AUTHOR]

On the basis of a review of data on the effective cross-sections of particle interactions, computations of the effective electron-neutron interaction, of the cross-section values for H, H and He were carried out in the range 0.8 ⩽ ϑ ⩽ 1.7 and 2.5 ⩽ log P ⩽ 6.5. The mean cross-sections for the solar mixture used by Zwaan were computed (see Table II). Using these results, the values of the electric conductivity and of its anisotropy coefficient were computed (see Tables VII and VIII), as well as other auxiliary quantities. The conductivity values obtained are in the range from 5 × 10 to 5 × 10 CGSE units for the assumed physical conditions. [ABSTRACT FROM AUTHOR]

The energy release by Joule magnetic-field dissipation in the solar atmosphere is discussed. It is shown that the heating is unimportant in the case of granulation and intergranular space. In the case of spot features the additional temperatures ΔT with the accounting of the radiation losses are no more than 30° for small new spots, ≈ 1° for the large umbrae and 300° for bright points in large umbrae. This effect gives the possibility to suggest a hypothesis on the source of temperature inhomogeneity in the spot umbra and the nature of bright points. In the chromosphere the dissipation is negligible. [ABSTRACT FROM AUTHOR]