A SYSTEMATICALLY VARYING PERIOD WITH AN AVERAGE LENGTH OF 28 MONTHS IN WEATHER AND SOLAR PHENOMENA.1

Abstract

Abstract SYNOPSIS During the last 25 years a number of writers have called attention to a short cycle in weather elements and have given estimates of its mean length varying from 2.5 to 3.5 years. The diversity in these estimates is due in part to the practice of some investigators of using data with a time interval of 12 months, which leads to high values of the intervals; others employed consecutive 12-month means and derived values of 2.5 to 3.0 years. In the present paper various statistical criteria and methods are employed to show the extent to which a given succession of meteorological data, such as yearly means of temperature, differs from a purely fortuitous sequence of similar data. In high latitudes the mean interval between two consecutive maxima or minima is less than 3.0 years, which is the mean interval for a perfectly fortuitous sequence. This and other criteria indicate a systematic and persistent tendency to a recurrence of similar phases which differs from that due to chance alone and t...