ON THE ENERGY OF STORMS MARGULES 541 



we simply assume an initial stage generalized from actual observa- 

 tions. 



The restriction of the mass of air to a closed system, the assump- 

 tion of a well-defined boundary between the cold and the warm 

 air, the introduction of level surfaces of equal pressure, are all 

 analytical auxiliaries that we employ in order to ascertain the 

 value of the available kinetic energy of a perfectly definite system. 



§(8) If we are to give abroad interpretation to the results of our 

 analyses, we must omit numerical details. The phenomena of 

 motion in the great storm areas that we call cyclones are less intelli- 

 gible than those of the boe-en. But these also, at least in median 

 and higher latitudes, consist of warm and cold masses of air lying 

 adjacent to each other horizontally; cold air often spreads out over 

 the earth in the lower strata behind the passing storm. It is there- 

 fore not unlikely that these storms are fed by the potential energy 

 of an initial stage similar to that which we have adopted in the 

 preceding lines. 



The opinion that the energy of cyclones arises from the overturn- 

 ing of masses of unequal temperature has been expressed in recent 

 years by Prof. F. H. Bigelow. In one of his memoirs 6 we find the 

 following sentence: 



"The cyclone is not formed from the energy of the latent heat 

 o f condensation, however much this may strengthen its intensity; 

 it is not an eddy in the eastward drift, but is caused by the counter- 

 flow and overflow of currents of air of different temperatures." 



Long ago W. Blasius had vainly labored to introduce a similar 

 view as to the origin of storms. In his books (Storms, Philadelphia, 

 1875; an d "Sturme and Moderne Meteorologie, " Braunschweig, 

 1893) this idea is found mixed up with other views that are, I 

 believe, less reasonable; however, they deserve careful considera- 

 tion. From giving too much attention to the isobars, it has been 

 generally assumed that the air must ascend only in the central part 

 of a region of low pressure and that the motions are nearly sym- 

 metrical about this. Ferrel as well as Guldberg and Mohn have 

 built on this assumption. 



Our analysis gives us only a general idea as to the source of the 

 energy of storms; a working model of the cyclone with symmetrical 

 distribution of temperature has not yet been constructed. 



6 "Studies on the meteorological effects of the solar and terrestrial phys- 

 ical processes. Weather Bureau publication, No. 290, "Washington, 1903, 

 p. 37; separate print from the Monthly Weather Review, Feb., 1903, p. 84, 

 column 2. 



