50 The Fruit-Growers Guide-Book 



off the warm waters of the Japan current that sweeps 

 the Pacific coast. The eastern shore of Lake Michigan 

 has a warmer climate than the opposite side, on account 

 of the lake currents which keep open water on the eastern 

 side while the other shore is ice bound. 



On account of the movements of warm currents of air 

 oranges are being grown in the southeastern corner of 

 North Carolina, two hundred miles north of the northern- 

 most place at which it is considered safe to grow this fruit 

 on the Atlantic coast. This is because the warm waters 

 of the gulf stream come in close to shore at this portion of 

 the coast and the temperature of the air is less frosty than 

 farther south. 



Natural prominences, such as high bluffs which absorb 

 the heat of tiie sun during the day and then radiate it 

 slowly at night have a great effect in ameliorating the 

 night temperature in small localities, although this influ- 

 ence cannot be counted of any serious value in protecting 

 an orchard against late frosts in the spring. In the moun- 

 tain sections of the Western states districts near the 

 mouths of great canons are frequently safe from serious 

 damage from frost in late spring on account of the con- 

 tinual breeze which flows or blows out of the canons dur- 

 ing the night. These breezes come from the cooler air 

 which surrounds the high tops of the mountains, flowing 

 down their sides into the lower grounds in the valleys. 



While natural conditions are of material assistance, 

 they cannot be depended upon as being of absolute cer- 

 tainty in protecting against frost, for the vagaries of air 

 currents and frostless belts are as uncertain as the flight 

 of a bird. In many fruit producing districts there are 

 ardent promoters of certain areas as being frostless, be- 

 cause of some natural condition which provides favorable 

 air currents or temperatures at critical times. However, 

 it may be but a short time until those conditions change 

 and the frostless area is seriously damaged by a freeze. 

 It was not many years ago that the orange growers in 

 Florida believed that the southern limit of frost was at 

 the northern boundary of that state. However, in 1895 it 



