•122 Bigelow — Meteorological Elements of the United States. 



Synchronism of the solar prominences and the European mag- 

 netic field with the temperatures, vapor p7'essures and baro- 

 metric pressures of the United States in the 11-year and the 

 3-year periods. 



1. An inspection of these curves indicates that there is a clear 

 synchronism between the numbers of the prominences and the 

 terrestrial magnetic field in both the long and the short peri- 

 ods, showing that if the prominences stand as representatives 

 of the solar activity, the intensity of the radiation, electro- 

 magnetic or magnetic, varies with it in such a way as to mod- 

 ify the strength of the earth's magnetic field from year to 

 year. It should be noted that there is a tendency for the short- 

 period curve to lag somewhat, possibly several months, behind 

 the solar curve. This suggests very interesting speculations 

 between the time of formation of the solar impulses gener- 

 ating the prominences, and those producing the radiation. Do 

 the great heat and radiation waves pass from the interior to 

 the surface of the sun in such a way that the prominences first 

 feel the impulse in the solar circulation that produces them, 

 and afterwards does the main flood of radiant energy follow 

 from the interior of the sun \ It becomes a problem in circu- 

 lation and convection of heat on the sun, just as in the earth's 

 atmosphere the maximum of heat and the minimum of cold 

 lag about 40 days behind the position of the sun causing them. 

 It has been pointed out, furthermore, that the temperature 

 variations recorded in these tables are a product of circulation 

 in the temperate zones rather than of direct radiation, as might 

 hastily be assumed. 



2. A comparison of the curves on fig. 1, fig. 2, fig. 3 indicates 

 that the synchronism is better defined in the Pacific States 

 than it is east of the Mountains, and that while the long period 

 tends to break down, the short period persists with considerable 

 precision. This accords with the statement made on page 125, 

 Bulletin No. 21, Solar and Terrestrial Magnetism : " The occur- 

 rence of four subordinate crests in the 11-year period suggests 

 strongly that a 2 - 75 year period is superposed upon the long- 

 sweep of that periodic curve. Apparently this is more at the 

 basis of the seasonal variations of the weather conditions of the 

 United States than anything else, so that in long-range fore- 

 casting this period must be very carefully considered." If the 

 ten sections of the United States be plotted separately, it is 

 shown that the amplitude of the temperature, vapor pressure 

 and barometric pressure curves increases from south to north. 

 It is weakest on the Southern Rocky Mountain plateau, and 

 strongest in the Lake Region. 



3. The phenomenon of inversion is very clearly exhibited, 

 and it is fundamental in all these reseaches. In the long-period 



