272 



THE WEATHER 



Figure 198 shows the unusual paths of LOWS for March, 

 1910, the prevailing southerly winds resulting, and the remark- 

 ably high temperature over north-central United States. 

 Explain the temperature. 



Figure 199 shows the storm tracks for April 18-27, 1910, and 

 the attending cold weather over north-central United States. 

 Explain the cold. 



296. Unusual Paths of Highs; Resulting Weather. -In 

 Fig. 200 the paths of HIGHS for February, 1899, are seen, to- 

 gether with the unusually cold temperature of that month. 



FIG. 200. Unusual cold, February, 1899. Paths of highs that month. 



These are examples of the causes of many periods of unusual 

 weather. 



297. The Relation of Lows and Highs to the General Cir- 

 culation. The HIGHS and LOWS we have studied, although often 

 a thousand miles or more in diameter, are only comparatively 

 small eddies in the greater air streams of earth. They drift 

 along with the broad, general air currents much as the eddies in 

 a river drift along with the stream. Those broader movements 

 make up the general circulation of the earth's atmosphere. 



