Principal characteristics of amplitude variations of the magnetic cycle in terms of the Wolf number and Schove series over the past 500 years

Based on a study of magnetic cycle variations, a new interpretation of Mounder type minima is proposed, and a new such minimum is identified at the end of the past century and beginning of this century. A singular point is shown to exist in variations of the low-frequency component, which are thought to be related to variations of the quasi-constant magnetic field of the sun. The new data are used in a discussion of criteria for the construction of prediction models and of the mechanisms of solar cycles.