Tellus XIV (1962)
A problem of the methods involved in studying long-period climatic variations in the northern hemisphere is discussed. The data obtained at individual points are compared with circulation characteristics (ratio of the zonal and meridional components) for the whole hemisphere. In analysing the variability of the circulation use is made of the system developed by the author and his co-workers for typifying atmospheric processes over the hemisphere for the past 56 years. In view of the good agreement previously obtained between the long-period variations of these circulation types and solar activity it is considered that a continuous chain (sun-general circulation-climate of individual points) is set up by means of such a dynamic-climatological analysis. The existence during the first half of the 20th century of periods-“epochs”—differing in both circulation characteristics and average level of climatic values is established. The conclusion is drawn that it is for such epochs that climatic calculations and climatic classification should be made.