METEOROLOGY. o.jy 



818. Dr. Krankeuhagen, of Stettin, has iuvestigated the distribution 

 of temperature and pressure in Europe in June, and has shown that 

 the pcntade, June 10 to 14, is peculiarly liable to a slight fall of tem- 

 perature, while on the other hiind the isobars of June require such 

 winds as must produce this temperature fall. In general the areas of 

 low pressure that pass over Europe have a tendency to take a direction 

 toward the northeast, east, or southeast, and are therefore followed by 

 cold winds. [D. ^f. Z., i, p. 11.) 



319. Dr. Krankenhagen also contributes to the question of three cold 

 days in May a study based on the consideration that such may be caused 

 by especially cold, clear nights; he therefore calculates how many days 

 have been above the meaii, and how many below; the mean negative 

 departure we may call X, and positive departure Y; then the quotient 

 X -^ Y shows how many more times the mean negative (lei)arture is 

 greater than the positive. This ratio is 1.16 for the third pentade of May. 

 (D. J/. Z., I, p. 371.) 



320. Dr. J. van Bebber, of the Hamburg Seewarte, publishes the re- 

 sults of a study into typicnl weather phenomena in anticipation of a 

 more exhaustive publication by the Seewarte. This is a continuation of 

 his studies upon the geographical distribution, the paths and velocities 

 of barometric minima; his object now being to ascertain in what man- 

 ner these depressions influence the condition of the weather, especially 

 in Germany, and whether it is not possible from any given condition of 

 the weather to deduce practical rules for predicting the movement of 

 the depressions and the future weather. He first determines the prin- 

 cipal paths followed by the majority of the storm centers, leaving to a 

 future time the study of the erratic minima. The tabular view of the 

 frequency with which storms traversed these princij)al paths shows a 

 decided tendency of minima to follow in groups along any path once 

 inaugurated by a leading storm. He also shows that the mean velocity 

 of minima moving along the paths is always much greater than the 

 general mean velocity of all minima indiscriminately. Therefore we 

 conclude that along these principal paths the conditions are most favor- 

 able for maintaining the intensity and rapid progress of minima. If 

 we consider the distribution of pressure lor each of these paths sepa- 

 rately, we find characteristic relations ; thus, if a line be drawn from the 

 minimum to the maximum pressure, or from the minimum normal to the 

 closest isobars, we find the storm progress nearly perpendicular to this 

 line; in other words, the progress of the miuinuim agrees closely with 

 the direction of the strongest wind, thus agreeing entirely with the 

 princii)le announced in 1872 by Rev. Clement Ley, namely, "extensive 

 areas of very high pressure delay or turn aside the movement of a de- 

 pression, in that each depression moves with the greatest ease in a direc- 

 tion such that it shall have the highest pressure on the right-hand side 

 of its path." 



A relation is also apparent between the distribution of temperature 



