50 THE PRINCIPLES OF AGRICULTURE. 



The provision made by the United States for noting 

 conditions, and announcing indications, in all parts of 

 the country, is of great importance. It is of great value 

 in agriculture. The farmer, relying upon these indica- 

 tions, may select favorable weather for planting his seed 

 or harvesting his crops. 



Storms, The central section of a storm is noted by 

 an area of low barometer, or low pressure. That is 

 to say, it is where the atmosphere is lighter than 

 usual, and on that account is rising. In front and in 

 the rear of the storm center, the barometer is high, or 

 the atmosphere is heavy. In the United States, these 

 sections of low pressure, which mark the location of 

 storms, are generally long and narrow, extending 

 across the country from north to south. Storms usu- 

 ally appear first in the western or southern parts of 

 the country, and move in an easterly or northeasterly 

 direction. 



Naturally, the winds on both sides of the storm center 

 blow toward it. They are the heavier sections of air 

 passing in to take the place of the lighter sections, which 

 are rising ; hence, storms are generally preceded by east, 

 northeast, or southeast winds, and followed by west, 

 northwest, or southwest winds. 



Climate. The climate of a region is its condition with 

 regard to heat and moisture. It may be considered a hot 

 or cold, a moist or dry climate. 



The temperature in any locality depends chiefly upon 

 the following conditions : 



1. Latitude. The extent to which the earth and the 

 atmosphere near it become heated depends upon the di- 

 rectness with which the rays of heat from the sun fall 

 upon it. Sections near the poles are therefore colder 



