Some Features of the Climate of Indiana. 



BY VERNE H. CHURCH, SECTION DIRECTOR, U. S. WEATHER BUREAU. 



The absence of mountain ranges and large bodies of water with- 

 in, or oontiguoiis to, the State of Indiana, together with the level 

 character of its surface, gives it a comparatively uniform climate. 

 While Lake Michigan forms a part of the northern boundary, it 

 has very little influence upon the climate of the State at large, as 

 their relative positions do not permit of interchange of air cur- 

 rents in the regular course of the prevailing southwesterly winds. 

 There are local effects produced by the lake over a limited area in 

 its immediate vicinity, however. Altitude, direction of slope, char- 

 acter of surface, and various other influences affect the climate of 

 individual localities, but for the State as a whole, the climate 

 varies quite uniformly with the latitude. FolloAving the rule which 

 obtains where ideal climatic conditions prevail, there is a gradual 

 increase in both temperature and precipitation from north to south, 

 or, as it is often expressed, with decrease in latitude. 



The accompanying chart (Plate 3) shows that the annual mean 

 temperature ranges from slightly less than 48 degrees in the extreme 

 northern part of the State to slightly more than 56 degrees in the 

 extreme southern and southwestern parts. The northern half be- 

 ing comparatively level, the isotherms are more regular ajid more 

 nearly parallel there than in the southern half, where the surface 

 is much more broken. The irregularities in the isotherms are at- 

 tributed chiefly to local causes. The cold area in Henry, Wayne, 

 Rush, Fayette, Randolph, Franklin and Decatur counties is ex- 

 plained by the fact that this section of the State has an altitude of 

 more than 1,000 feet. The highest point in Indiana is 1,285 feet 

 above sea level and is located in the southern part of Randolph 

 County. A further examination of the chart discloses the fact 

 that the Wabash Valley is practically as warm at Terre Haute as 

 it is at the mouth of the Wabash River, a peculiarity attributed 

 to the topography of that section. 



However, a discussion of the mean temperature does not nec- 

 essarily give a true conception of the climate of a State as affected 



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