State Board of Forestry. 55 



The seasonal distribution of rainfall, while important in Indi- 

 ana as well as elsewhere, is of less significance than in the semi- 

 arid regions of the West, where the total amount for the year is 

 only sufficient for the current needs of vegetation. In Indiana, 

 the normal amount is ample for nature's requirements during all 

 seasons of the year, as is shown by the chart (Fig. 1) on preceding 

 page, which is introduced to illustrate graphically the monthly 

 am.ounts of rainfall. 



The precipitation has a comparatively uniform distribution 

 throughout all months of the year, because the State of Indiana 

 lies within the general storm track, and receives a portion of the 

 moisture from the majority of storms which cross the Ohio Val- 

 ley and lake region at irregular but frequent intervals. While 

 droughts sometimes occur during the summer months, they are 

 seldom severe enough to cause extensive damage to the staple crops 

 of the locality. 



The geographical distribution of rainfall is somewhat variable, 

 as an examination of the accompanying chart (Plate 6) will show, 

 in general there is an increase in amount from north to south. 

 Small areas in the northern half of the State have an average an- 

 nual amount of less than 36 inches; the remainder of the northern 

 half has from 36 to 40 inches, and the greater part of the southern 

 half has more than 40 inches. About one-third of the State, ex- 

 tending from the Ohio River northward, receives more than 42 

 inches. 



From this it is apparent that the precipitation in all parts of 

 Indiana, during an average year, is ample for all kinds of plant 

 life, and that, from the standpoint of both the temperature and 

 precipitation elements, climatic conditions in Indiana permit an 

 unusual variety in the character of its vegetation. 



There is a popular belief that our climate is changing, but a 

 stud}^ of all available statistics fails to bear out this opinion. There 

 are short-period variations in temperature and precipitation, and 

 it is possible that there are similar long-period oscillations. It is 

 to be regretted that there are but few reliable records covering a 

 long period of years. Those available show changes from year to 

 year in the temperature and rainfall of the respective places, but 

 there is nothing to indicate that a definite change in climate is ac- 

 tually taking place. They also show that, while the temperature 

 and precipitation elements are above normal in certain years, there 

 are other years when the same elements fall, in varying amounts, 



