Forecasting the Weather 



29 



lower left-hand corner is reached, where 

 it will be noticed temperature is 6o° 

 above zero. On the lower right-hand 

 corner temperature is only 40 above 

 zero. So far as temperature is con- 

 cerned , therefore, we note that the right- 

 hand* side of an area of low pressure 

 is warm and the left cold. 



The direction of the wind is shown 

 by the small arrows in different parts of 

 the diagram. These, it will be noticed, 



winds have a general southerly direc- 

 tion, in the northeast quadrant easterly 

 winds prevail, while in the northwest 

 and southwest quadrants the winds are 

 mostly northwest to west. An observer 

 stationed in lower Michigan at the point 

 A will have fresh easterly winds, shifting 

 as the storm center approaches him 

 around to the south by way of southeast, 

 and as the center passes him shifting 

 still farther to the west or northwest. 



Fig. 7. — Weather Map (reduced) of December 15, 1892, Showing Typical Winter 



Storm 



are disposed about the center of the 

 storm (the inmost oval marked ' ' Tow ' ' ) 

 in a rather orderly system. The wind 

 does not blow directly toward the center, 

 but rather spirally about it, as discov- 

 ered a little more than half a century 

 ago. In the southeast quadrant the 



* A person standing in the center of a storm, 

 facing in the direction in which the storm is 

 moving, will have the warm side on his right 

 hand and the cold side on his left and in the 

 rear. 



This is what is meant by ' ' shifting with 

 the sun." On the other hand, an ob- 

 server in South Dakota at the point B 

 first experiences a wind from the north, 

 and as the storm center approaches and 

 passes him the wind backs to the west 

 by way of northwest, and this is the 

 meaning of the term "shifting against 

 the sun, or backing. ' ' The weather ex- 

 perienced in the two locations, A and B, 

 will differ as regards both temperature 

 and precipitation. At station A the tern- 



