86 General A. W. Greehj — Geograpliy of the Air. 



status. Of meteorology, however, using this term as especially 

 applying to weather and not to climate, which will be referred 

 to later, it may fairly be said that the generalizations are too 

 indefinite in terms and too scanty in number, the ascertained 

 and acknowledged facts too insufficient as well as too disjointed 

 in their relations, to form the indispensable work of fundamental 

 principles whereon is to be woven the regular, graceful curves 

 which nature ever presents to us under the magic wand as waved 

 by the specialist in any science. 



The term " science "' carries with it in a degree the idea of 

 prevision, so that exemplifications of its principles shall always 

 fiiid expr.ession in foreseen results, whose ultimate variations 

 should not exceed certain narrow limits. 



Abercrombie and the writer have published, almost simul- 

 taneously, the latest works in English on the weather. My OAvn 

 opinions as to the status of this department of nature were 

 clearly put in " American Weather," 1888. To quote : 



"All skilled meteorologists realize how comparatively local are weather 

 conditions and how impossible it is, at times, to make predictions for a 

 definite period with any feeling of certainty. * * * It is evident that 

 faii'-weather conditions are those which are most persistent [i. e., i\\Q\ 

 partake more of climatic conditions thaii of weather] and from the pre- 

 diction of which the highest percentages of accuracy will be obtained." 



Professor Marvin, a careful, conscientious official, whose duty 

 has included the examination and verification of forecasts, after 

 three years of study, says (referring to verification-percentages 

 not being strictly comparable) in confirmation : " The reasons 

 for this are principally because of the much greater difficulty of 

 successfully forecasting rainy and unsettled than fair weather, 

 together with the seasonal spasmodic variations in their respect- 

 ive occurrences." His illustrations make clear what has been 

 believed by all close observers, namely, that high percentages 

 and satisfactory forecasts are attendant on the persistency of 

 climatic or permanent conditions (such as no summer rain in 

 California) when unbroken by the violent and marked changes 

 which distinguish weather from climate. 



It is safe to say that the percentage of successful forecasts of 

 rain twenty-four hours in advance is not one-half, and probabl}^ 

 not more than one-third, so successful as forecasts of fine, clear 

 weather for the same period. 



