E. Loomis — Contributions to Meteorology. 



column 4th shows the difference between these two directions. 

 The directions are all measured from the north point toward 

 the east. 



Comparison of storm paths with wind directions, United States. 



Bismark 



Ft. Sully 



Breckenridge 

 North Platte 



Keokuk 



Yankton 



Omaha 



Davenport. .. 



Dubuque 



St. Paul 



LaCrosse 



Pembina 



Wind blows 



Storms move 



Storms most 



towards 



towards 



northerly. 



N. 162-7° E. 



N. 107-7° E. 



+ 55-0° 



154-2 



106-7 



47-5 



126-2 



105-5 



20-7 



12D0 



104-1 



16-9 



104-7 



88-3 



16-4 ■ 



121-6 



106-3 



15-3 



114-7 



100-8 



13-9 



96-8 



87-0 



9-8 



92-7 



88-3 



+ 4-4 



78-0 



99-3 



— 21-3 



67-1 



90-5 



— 23-4 



85-7 



109-4 



-23-7 



We see that at all of the stations, except the last three, the 

 average wind of winter blows toward a point somewhat south 

 of east, and for four of the more western stations, the average 

 direction is 51° south of east. We also see that at the more 

 western stations, the average movement of storm centers is 

 toward a point considerably south of east, but at the more 

 eastern stations the direction is a little north of east. At Bis- 

 mark and Fort Sully, the average course of the winds is 50° 

 more southerly than that of storm paths, while at St. Paul, 

 La Crosse and Pembina it is 22° more northerly. 



The facts here stated afford a basis for some general con- 

 clusions respecting the movement of storm centers. Some 

 meteorologists have claimed that the progressive movement of 

 storm areas is satisfactorily explained by saying that they are 

 carried forward by the general movement of the mass of the 

 atmosphere within which they are formed ; that is, they drift 

 in a sense similar to that in which waves, eddies, etc., formed 

 on the surface of a river, drift with the current. They advance 

 as the water of the river advances, and in the same direction. 

 But we have found that the average direction of movement of 

 areas of low barometer does not generally coincide with the 

 average direction of the wind for the same region. This is seen 

 not only in the case of tropical storms, but also in storms of 

 the middle latitudes. 



But it may be claimed that the progress of storm areas is not 

 determined entirely by the average movement of the atmosphere, 

 but by that movement which is taking place at the date of the 

 storm. There is some reason to think that in the case of trop- 

 ical cyclones, particularly in the China Sea, the wind which 

 generally prevails at the time of the cyclone accords more 



