14() A YEAR IX SCIENCE 



air would move north in the northern hemisphere and 

 south in the southern hemisphere. The air moving 

 toward the equator would move directly south in 

 the northern hemisphere and north in the southern. 

 The rotation of the earth, however, turns the currents 

 of air to the right in the northern hemisphere and to 

 the left in the southern. (See Figure 52.) Thus in the 

 temperate regions of both hemispheres, the winds 

 usually come from the west. These winds are known 

 as the prevailing westerlies. The winds blowing from 

 the regions of high pressure toward the equator are 

 known as the trade winds. They blow obliquely toward 

 the equator from the northeast and from the south- 

 east. These winds have been given their name on 

 account of the steadiness with which they blow. Navi- 

 gators have- known of these w r inds and have taken 

 advantage of them for ages. 



The prevailing westerlies are of the most importance 

 and of the most interest to us because the United 

 States lies in their region. Because of the regularity 

 of these winds most of our storms move eastward. 

 We are all familiar with the fact that our storms are 

 generally first seen in 'the west. 



Land and sea breezes. If you have lived near a 

 large body of water, you are familiar with the cool 

 breezes which blow from the water over the land 

 during the day, and in the opposite direction at night. 

 Land heats and also cools more rapidly than water. 

 As a result, during a hot day the land becomes warmer 



