336 Fruit-growing in Arid Regions 



visionary neighbor. . Something went wrong; the air-cur- 

 rents failed to work. 



The degree to which any locality suffers is, in many cases, 

 a matter of chance. Mountainous sections are noted for 

 their varieties of climate, and it is not uncommon to find 

 localities differing very little in altitude and not over ten 

 miles apart, showing a variation in season of blooming of 

 almost as many days. So while one locality may be caught 

 at a critical time one year and a neighboring locality 

 escapes, it very often happens that the experiences are 

 reversed the following spring. Yet we know that there is 

 such a thing as natural protection; and there are localities 

 that seldom suffer from untimely frosts. 



One of the most reliable means of natural protection is 

 that furnished by canon breezes. Orchards in narrow val- 

 leys often escape injuries from frost, as the currents of air 

 flowing down from higher altitudes keep the air moving, 

 and thus prevent the settling of the colder air. Proximity 

 to high bluffs that absorb a large amount of heat from the 

 sun in the day and give it off gradually at night is also 

 considered to be valuable protection. Orchards border- 

 ing on open areas, as desert land, are often only slightly 

 injured, while those surrounded by other orchards suffer 

 severely. The escape of the orchard on the border is ap- 

 parently due to a better circulation of air. Low spots 

 surrounded in the greater part by higher elevations are 

 more often visited by untimely frosts, while ridges sur- 

 rounded by lower levels are more exempt. These few 

 factors account in part for the " spottedness " of frosts, 

 but there are some variations that these factors will not 

 account for. The grower who harvests a good crop one 



