380 



ENVIRONMENTAL CONDITIONS. 



We have prepared another chart of this kind by superimposing the 

 chart of the physiological summation indices of temperature for the 

 average frostless season (plate 40 and fig. 1) upon that of the precipi- 

 tation-evaporation ratio for the average frostless season (plate 57 and 

 fig. 16), and the result is shown in figure 19, where the broken lines 

 represent temperature conditions and the full ones represent condi- 

 tions of moisture. On this chart each of the five temperature provinces 

 is subdivided into four moisture provinces and the country is thus 

 represented as a mosaic of small areas of various shapes and sizes, each 

 area being characterized by a certain range and amplitude of the 

 temperature index and also of the moisture index. Following our 

 previous usage, climatically descriptive adjectives may be employed 



129' 127 12j 1 



ti" 121° 111" 11!" Ilo" 113° 111° 10-/ 107° 105° 103° 101' aa° 97° 95' M' ai' 89' »;' ".v ^f 81* '8' 77° :i 



71 CT 07 66 



119 117 115 117° 111° 10V° 



107' 105° 103° 101° 99° S7° 9S° 9S' 9r 8U° 



Fig. 19. — Two dimensional moisture-temperature provinces, being a combination of figures 1 and 

 16. Broken lines limit temperature efficiency provinces (fig. 1), full lines limit precipitation- 

 evaporation provinces, (fig. 16). (See also Plates 40 and 57.) 



in designating these ranges of index values, and two such adjectives 

 suffice to describe any one of the irregular areas shown on the chart. 

 Thus, we may refer to the warm semiarid province, the mediurn humid 

 province, the cool semihumid province, etc., each of these provinces 

 including the coincident or overlapping portions of the corresponding 

 temperature and moisture provinces. 



An examination of figure 19 shows, however, that several different 

 geographical areas may be characterized by the same pair of adjectives, 

 and these may be designated by geographically descriptive terms, 



