356 



SCIENCE PROGRESS 



TABLE SHOWING PRINCIPAL MONTHS OF CYCLONIC FORMATION AND 

 APPROXIMATE ANNUAL FREQUENCY 



being well represented. At first sight the Indian cyclones 

 may seem to form an exception, since they occur in the south- 

 west monsoon current and not in the trade winds, but in 

 reality the rule holds, for the monsoon current is known to be 

 a deflected trade wind which has followed a very long track 

 across the warm ocean. Turning now to a more detailed 

 consideration of the table showing the seasonal distribution of 

 the storms of each region, those of the Indian area are seen 

 to present unique features. They set in early, yet have 

 their principal maximum late in the autumn. They are 

 infrequent during late summer and early autumn — ^the most 

 prolific period in all other parts of the world. This statement 

 holds only with regard to the most severe Indian storms ; 

 if all cases of cyclonic wind circulation in which gales (force 8) 

 occur were to be considered the figures for monthly frequency 

 would be more in accordance with those for other regions, and 

 would show only a more prolonged " season." In all other 

 regions the " season " extends from slightly past the summer 

 solstice to the middle of the autumn. 



Characteristics of Individual Storms. — The remarks made in 

 the first paragraph of these notes indicate how closely the 

 tropical cyclones, once formed, resemble one another in different 

 parts of the world. Reliable instrumental observations have 

 not often been made near the inner area of the storm owing 

 to the dangerous violence of the wind. Ballou ' has, however, 



* For the Bay of Bengal, only the severest storms are included. 



* For the Arabian Sea, storms of quite moderate intensity are included and the 

 figure for annual frequency is not comparable with that for the Bay of Bengal. 



^ " The Eye of the Storm," Am. Met. Journal, 9. 1902, pp. 67-84. 



