February 14, 1919] 



SCIENCE 



159 



it clearly is in temperature equilibrium when 

 and only when it loses as much energy by 

 radiation as it gains by absorption. Further- 

 more, so long as its chemical nature remains 

 the same its coefficient of absori^tion is but 

 little affected by even considerable changes 

 of temperature. Therefore, whatever the na- 

 ture of the object, since it is exposed to twice 

 as much radiation when between the two 

 planes as it is when facing but one, it must, 

 in the former case, both absorb and emit twice 

 as much energy as in the latter. That is. 



£•,= 2*', 



in which E^ and E^ are the quantities of heat 

 radiated by the object per second, say, when 

 between two planes and when facing but one, 

 respectively. 

 Again, 



£j = K.T,"^ 

 and 



E, = A',r,"' 



in which T, and T^ are the respective absolute 

 temperatures of the object under the given 

 conditions, and K and n its radiation con- 

 stants. 



For every substance there are definite val- 

 ues of K and n which, so long as the chemical 

 nature of the object remains the same, do not 

 rapidly vary with change of temperature. 

 Hence, assuming K„^K^ and n„^n^, it 

 follows, from the above equation 



E, = 2E,, 



that 



From this it appears that there must be some 

 temperature T^ below which the radiation of 

 the earth and lower atmosphere will not per- 

 mit the upper atmosphere to cool, though what 

 it is for a given value of T., depends upon the 

 value of n. 



But as already explained the value of 3"^, is 

 roughly 259° A., and if n^i, the value for a 

 full radiator, it follows that 



r, = 218'' A., 

 substantially the value found by observation. 



STORM EFFECTS ON TEMPER.ATURE (JUADIENTS 



Another surprising and, for a time, discon- 

 certing contribution of the sounding balloon 

 to our knowledge of the air relates to the 

 relation of the temix?rature of the atmosphere 

 to storm conditions. It has long been known 

 that, in general, areas of low pressure — cy- 

 clonic areas — are accompanied by inwardly 

 spiralling winds and precipitation; and, con- 

 versely, that areas of high pressure — anticy- 

 clonic areas — are characterized by outwardly 

 spiralling winds and clear skies. Certainly, 

 then, the inwardly flowing winds of the cy- 

 clone must ascend, and the outwardly flowing 

 winds of the anticyclone mu.st be sustained 

 by descending currents. And the nest infer- 

 ence, namely, that the air of the cyclone is 

 relatively warm and the air of the anticyclone 

 comparatively cold, seemed equally certain; 

 for, indeed, what else could cause ascent in 

 the one case and descent in the other? But 

 again the facts are not in accord with the 

 simplest and most obvious inference, but 

 just the reverse, through all convective levels, 

 that is, up to tlie base of the stratosphere, as 

 shown by Figs. 2 and 3, except, in general, 

 near the surface, during the winter. In 

 short, quite contrary to familiar ideas about 

 convection, the ascending air in this case is 

 relatively cold and the descending air com- 

 paratively warm. And the stratosphere, as 

 these figures also show, but further confounds 

 this confusion, for hero the temperature rela- 

 tions are again reversed, the warmer air being 

 now over cyclones and the colder, above anti- 

 cyclones. 



The facts just stated wore, indeed, for a 

 time somewhat disconcerting, but they have 

 helped to the realization that with reference 

 to temperature there are two classes of extra- 

 tropical cyclones, cold (migratory) and warm 

 (stationary) ; and also two classes of anticy- 

 clones, warm (migratory) and cold (sta- 

 tionarj'). 



That the atmosphere of a stationary anticy- 

 clone should average relatively cold, and that 

 of the cyclone comparatively warm, is obvious 

 from the fact that the former occurs only 



