Solar Magnetic Period. 449 



The next step in the progress of this investigation is to 

 determine the physical function for the transformation of the 

 energy of the solar magnetic fields, the electromagnetic and 

 the magnetic, into the equivalent heat-energy that exhibits 

 itself in temperature changes. There are many difficulties in 

 the way of this step, but it is hoped that they can be overcome 

 before long. 



Formation of Anticyclonic and Cyclonic Circulations. 



One of the most remarkable facts regarding the develop- 

 ment of the theories of the origin of the Anticyclones and 

 Cyclones of Middle Latitudes, is the excessive weight ascribed 

 to the cyclones. This is perhaps due to a popular interest in 

 the system of winds accompanying Low Areas of Pressure, 

 and to a supposed resemblance between these and the general 

 circulation of the air. Vertical convection currents are said to 

 be the primary source of the movement, and some have seen in 

 the High Areas only the pericyclonic overflow ring, as if these 

 were secondaries to the Lows. 



The real order of events in nature may, however, be sum- 

 marized as follows : The Equatorial Field generates a tropical 

 High pressure, and a sub-polar Low pressure belt, by its dis- 

 tribution of temperature. The continents rearrange these belts 

 so that in winter the small polar circuit surrounding the Ice- 

 landic permanent Low, supersedes and predominates, while in 

 summer the great mid-latitude circuit regains its supremacy. 

 Therefore in winter the circulation of the polar circuit is more 

 rapid, being smaller in diameter, the supply comes across the 

 North American Polar regions, and but little from the Pacific ; 

 in the summer the slower eastward march in the wider circuit 

 sets in, with the supply from the Pacific. In both cases the 

 movement of air masses is dominated by the varying intensi- 

 ties of the polar magnetic field from the sun, by which the 

 densities of the contents of the unit volume is changed. High 

 Pressure areas are the primary products of these sources of 

 energy, being in part whirled up by the general circulation, 

 and in part the result of reducing the polar absorption by dimi- 

 nution of the cosmical energy on certain dates. Between two 

 successive areas of greater density lies an area of smaller 

 density, where absorption of magnetic radiation has been more 

 vigorous. Under the force of gravity the adjacent sides of 

 the denser areas are drawn together, and meet abruptly along 

 the axis of the low section, in the so-called " trough." The 

 characteristics are that southern warmer air reinforces the high 

 pressure outflow, and transports its charge of aqueous vapor m 

 the current ; this meets the colder sheet from the north, in a 



