Notes on Climatic Boundaries in the Eastern United States

T HE Koppen climatic classification indicates a certain pattern of distribution on a world and on a continental scale that, in its gross features, is suggestive of major landscape differences when they too are considered on the same scale. In detail the value is limited in that the boundary lines express purely arbitrary values of combinations of meteorological elements that may or may not represent actual conditions locally. On a continental or a world scale they do indicate, specifically, direction of climatic change. They do not show ironbound limits pigeonholing invariable climatic types. The fact of variability is so frequently overlooked as almost to eliminate the geographical worth of the classification. This is particularly true in mid-latitude areas, which owe their climatic regime in a large part to the vagaries of cyclonic storms. The Koppen classification may be used to demonstrate the variability of climate, comparable to that of weather under these conditions, and, at the same time, to suggest a more accurate conception of the true character of climatic boundaries.'