Ordinary Storms. 



575 



3E-J 



FIG. 268. Chart of strongly developed low area iii the vicinity of the 

 Great Lakes. 



731. Duration of Ordinary Storms. The length of time 

 one of the ordinary cyclonic storms of the atmosphere lasts 

 is very variable. In some cases they are of but a few days 

 duration ; at other times they last for weeks together and in 

 that time travel long distances. 



It is common for them to cross the United States, the 

 North Atlantic and the whole of Europe ; and one, unusual 

 at least in the completeness of its known history, has been 

 followed from the vicinity of the Philippine Islands, 

 across the Pacific, across North America and the North 

 Atlantic; across Europe and well on toward the central 

 portion of Siberia, where lack of sufficient observations 

 prevented following it farther. 



732. Relation of the Region of Precipitation to the Storm 

 Center. The region over which rain or snow falls during 



