LONG-PERIOD FLUCTUATIONS OF THE GENERAL CIRCULATION OF THE ATMOSPHERE

This paper summarizes certain facts of observation, as reported by a number of investigators, concerning the nature of climatic variations on the earth's surface during observational time, during postglacial or historical time, and during the geological past. Particular emphasis is placed on possible interpretations or explanations of these changes. The discussion of the secular variations of the world weather patterns during observational time stresses on the one hand apparent relationships between these variations and solar activity, as indicated by sunspots, and on the other hand the essential similarity of these secular variations to those which occur from week to week and month to month in the fluctuation of the general-circulation pattern between more zonal (high index) and more cellular (low index) characteristics. The discussion of the variations of world climate during geological time is concerned primarily with the relative merits of the three principal theories which currently attempt ...