National Geographic : 1893 Apr 29
58 Gen. A. W. Greely-Rainfall 'Ifpes of the United States. characteristics are scarcity of precipitation during the spring months, April being very decidedly the month of least rainfall followed by October, and a heavy rainfall during the late sum mer and late autumn months with the maximum precipitation in November and nearly as heavy rain in July or August. The heavy rainfalls of the Saint Lawrence valley during November are the more remarkable in view of the fact that in this month the minimum precipitation occurs from northern Florida to central New York. Detailed data regarding this type is not at hand, but Professor Charles Carpmael, chief of the meteorological service of the Dominion of Canada, is authority for the statement that the minimum precipitation occurs in April at Kingston, Rockliffe, Montreal, Quebec, Father point, Saugeen, and Parry sound, as well as throughout the province of New Brunswick. It is in teresting to note that in the composite rainfall types of New foundland and New Brunswick, as well as along the greater part of the Massachusetts and Maine coasts, the November max imum obtains, and is as a rule the principal maximum, with March as the month of secondary maximum, although in some localities these maxima are reversed in order of importance. There may possibly be added a Gulf type, so called from its prevalence along the northern shores of the gulf of Mexico, where the maximum rain falls in September and the minimum in the early spring. Western Florida and the Texas coasts are the only sections in which this obtains. The normal daily rain fall at Key West, Florida, of 47 years, is .107 inch, with depart ures as follows: January,- .038; February,- .050; March, - .062; April, - .064; May, - .006; June, .044; July, .022.; August, .055; September, .111; October, .053; November, - .038, and December, - .043 inch. It is not within the scope of this paper to discuss the special causes which produce these differing types of rainfall distribu tion in North America. It may be said, however, that there is no doubt in my mind that the maxima and minima phases of precipitation are simply the result of the fluctuation throughout the year of atmospheric pressure over North America and its contiguous waters, thus affecting the relative positions of high and low areas and consequently causing winds, either favorable or unfavorable to precipitation, according to season and locality.
1893 May 05
1893 Apr 7