Location and Site of the Orchard 43 



orchards have been relatively high. Yet there are excep- 

 tions under certain conditions, though these do not in any 

 degree affect the prevailing preference for the higher ele- 

 vations. 



Sometimes in periods of rather intense cold that are ac- 

 companied by high winds, the fruit-buds will be killed at 

 the higher points and escape injury at the lower places. 



Another condition due to the modification of temperature 

 by elevation is suggested by what occurs repeatedly in the 

 orchard shown in Plate VII. The orchard extends to the crest 

 of the ridge, which is about 2100 feet above sea level. The 

 lower side of the orchard drops below the crest 400 or 500 

 feet, while the floor of the valley is several hundred feet 

 below the orchard. While the cold air obviously drains 

 from the orchard to the floor of the valley and during the 

 winter and early spring the temperature in the valley is 

 doubtless lower than at any point on the part of the slope 

 occupied by the trees, the warmest zone is evidently some- 

 where between the orchard and the valley floor. Not infre- 

 quently the trees in the lower part of the orchard blossom 

 two or three days earlier than at the upper side and there 

 is a corresponding difference in the ripening of the fruit in 

 some seasons. Thermometer records made at different 

 elevations along the slope show consistent temperature 

 differences that correspond with the behavior of the trees. 



These phenomena might at first appear to contradict 

 the statements made above in regard to the importance of 

 relative elevation in orchard sites. They are in perfect 

 harmony, however, with the well-known fact that above 

 certain limits of elevation the air becomes increasingly colder 

 until the line of perpetual snow is reached in the higher 

 mountains, even though a tropical or subtropical climate 



