SYNCHRONOUS ANNUAL VARIATIONS 
335 
The inverse type prevails annually, October 15 to February 1. 
These facts of periodic action from the sun in the equatorial 
period of 26.68 days, together with the semiannual inversion 
of the type, indicate that the problem of the solar radiation at 
the sun, and in its effects throughout the earth’s atmosphere is 
an exceedingly complex phenomenon, which will require extensive 
researches of various kinds. 
By way of suggestion it may be seen on Fig. 67 that if the 
incoming radiation transforms a part of its energy in the cirrus 
region into positive (+) and negative ( —) ions, it may be 
supposed that they seek the poles of the earth in opposite direc 
tions, as (+) to the north pole and the ( —) to the south pole, 
completing their circuit through the outer shell of the earth. 
This generates the magnetic vector system pointing southward, 
and the corresponding earth electric currents; at another time the 
(+) ions seek the south pole and the ( —) ions the north pole, 
thus producing the northward vectors, and the corresponding 
earth electric currents. This reversal of direction from time 
to time depends upon the physical condition of the atmosphere 
as a conducting medium for the ions, its congestion of ions, its 
accumulation of ice and vapors, producing the magnetic vectors, 
auroras, magnetic storms, electric currents, in the well-known 
conditions as observed. The energy expended at the earth 
is that transformed from the solar radiation; it is inexhaustible 
in amount, and depends for the observed aperiodic irregularities 
upon the prevailing states of the solar and terrestrial atmospheres. 
The Synchronous Annual Variations of the Solar and the Terres 
trial Elements 
The possibility of a scientific forecast of the type of weather 
likely to prevail in a large country as the United States or 
Argentina, whether the coming year is to be rainy and cool, or 
dry and warm, depends upon the establishment of the following 
two propositions: (1) The radiation output of the sun is a 
variable quantity, as 4 or 5 per cent, each side of the mean; 
(2) The meteorological elements, temperature, barometric and