226 POMOLOGY 



face is composed. According to Hann,^ if the specific heats 

 of equal weights of water and dry soil are compared, the latter 

 would be 0.2 of the former, but when equal volumes are com- 

 pared, the specific heat of the land is about O.G that of water. 

 In other words, if equal quantities of heat are received by 

 equal areas of land and of water, the land will have its 

 temperature increased almost twice as much as the water. 

 Therefore, this slowness with which water takes up and gives 

 up its heat accounts for the more equable temperature of 

 land adjacent to large bodies of water, particularly on the 

 leeward side. The more exposed the land area is to the 

 influence of ocean winds, the more uniform is its tempera- 

 ture. 



The case cited later of the western section of the state of 

 Michigan illustrates this fact as it pertains to pomology. 

 Just as marine climates are more equable, so continental 

 climates are characterized by a great range of tempera- 

 ture. 



197. Mountain versus valley climates. — One of the teach- 

 ings that has become axiomatic in fruit-growing is to plant 

 orchards on elevations and avoid valleys, coves, or other 

 places where the movement of the air is restricted. This 

 doctrine is based on the fact that the cold air drains from 

 the high lands into the valleys and often results in damage 

 to the crops in the latter places when those on the higher 

 elevations may escape injury. Other factors, such as hu- 

 midity of the atmosphere, also play an important part in the 

 behavior of plants in valleys and on mountains. In general, 

 a climate characterized by low humidity and bright sun- 

 shine throughout the growing season will usually produce 

 a fruit which has a clear skin and is comparatively free from 

 such diseases as scab and sooty fungus. Such a climatic 



' Hann, Dr. Julius. Handbook of Climatology. Eng. Trans. The 

 Macmillan Cpmpany, New York. 1903. 



