CROP REGIONS OF OHIO 61 



as an average temperature below which plants do not grow very 

 actively. In other words, it is the threshold of our spring season 

 as far as the temperature is concerned. Although the station's 

 records used in the chart are rather scattered in the southeastern 

 portion where temperature varies most and where therefore the 

 stations should have the highest distribution frequency from our 

 point of view, some allowance has been made for elevation. This 

 chart will be modified in the future as increased data seem to war- 

 rant it. 



Columbus, on the fortieth parallel of latitude is slightly south 

 of the center of the state. The extreme southern portion of the 

 state extends a little south of 38° 30' N. latitude. The northern- 

 most point almost touches latitude 42°. This position of Ohio af- 

 fects the seasons and the total amount of energy received from the 

 sun. At Columbus the length of the day varies from nine hours 

 and twenty-one minutes on December 15th to fifteen hours on 

 June 15th.^ During the longest days of summer the average 

 length of the day is almost eighteen minutes longer in the north- 

 ern part of the state than in the southern. Reference to Part I is 

 sufficient to inform the reader that the dispersal of the energy is 

 of greater importance in plant and animal geography than the total 

 absorbed, so we may pass this point without further comment. 

 Smith ('12) loc. cit. has described the general climatic conditions 

 of Ohio as follows : 



"Ohio is in the path of the general low pressure or storm 

 areas which move across the United States from west to east. 

 These areas move at an average speed of 600 miles in twenty-four 

 hours and are preceded by southerly winds and high temperature, 

 and followed by northerly winds and lower temperature. They 

 are usually accompanied by cloudy weather and precipitation and 

 each storm causes an average of from one to two rainy days at 

 each place as they pass across the state. 



As there is an average of two of these storm areas each week 

 with fair weather periods between them, it follows that the 

 change in weather conditions is rather rapid. 



Yet Ohio is far enough from the coast so that the damaging 

 Gulf and Atlantic storms lose very much of their severity before 

 reaching our borders." 



1 These figures are for the year 1917. There is a slight variation, a few minutes per 

 day, from one leap year to the next. This is not of any significance in the present work. 



