i\ocbling jFunb 



SOLAR \'ARIAT10N ATTENDING WEST 

 INDIAN HURRICANES 



By C. G. abbot 

 Research Associate, Siititlisouian Institution 



West Indian hurricanes rarely occur except in the months June to 

 November. Table i shows the monthly distribution of 69 major hurri- 

 canes from 1923 to 1946. It seems probable that in these months, 

 especially in August, September, and October, there is such an un- 

 stable meteorological condition in those regions that only a slight im- 

 pulse suffices to precipitate the cataclysm. 



Table i. — Distribution of West Indian hurricanes, 1923-1946 



Month June July August September October November 



Number 3 5 19 25 14 3 



Many years ago the late Herbert Janvrin Browne came to me with 

 a dozen dates of first reports of West Indian hurricanes. He pointed 

 out that on these dates Smithsonian solar-constant values had been 

 depressed. I was so sensible of the accidental errors of individual 

 solar-constant results that I was inclined to regard his observation as 

 merely a coincidence. However, I prepared a table of sequences of 

 solar-constant values from 10 days before to 10 days after his dates. 

 The mean value of the 21 columns did indeed show a slight depression 

 at the date of first report, but so slight that I was disinclined to at- 

 tribute any significance to it. 



Since then the solar-constant values from 1923 to 1946 have all 

 been carefully gone over and revised to final form. They are now, of 

 course, several times as numerous as they were then. It has occurred 

 to me to re-examine this question with the advantage of better and 

 more extensive data. 



With the kind advice of the United States Weather Bureau, I col- 

 lected 69 dates, partly from the December numbers of Monthlv 

 Weather Review, partly from Tannchill's "Hurricanes," when major 

 West Indian hurricanes occurred in the years 1923 to 1946. Six of 

 these dates were omitted because of almost complete lack of solar- 



SMITHSONIAN MISCELLANEOUS COLLEaiONS, VOL. 110, NO. 1 



