The visibility function and its effect on the observed characteristics of sunspot groups. 7

For two different types of development of sunspot group areas, diagrams of the observation conditions of sunspot groups are used to demonstrate how the frequency distribution of sunspot groups in terms of their observed lifetime, their mean observed lifetime, the decrease in the number of sunspot groups towards the limb of solar disc, the number of observed sunspot groups and the number of new sunspot groups on the solar disc depends on the maximum sunspot group area and their real lifetime. The results obtained by modelling using observation condition diagrams of sunspot groups are compared with theoretical relations obtained for the partially linear approximation of the time development of the area of sunspot groups. (author). 16 figs., 4 tabs., 13 refs