DISCUSSION AND ANALYSIS OF WINDS. 



693 



S. E. Micliigan 



N. W. Indiana 



N. W. Ohio 



N. E. Ohio 



Toronto, Canada W 



Toronto, Motion of Upper Clouds 

 N. W. Pennsylvania .... 



W. New York 



S. W. Illinois 



N. and Central Kentucky . . 



E. Tennessee 



Central Virginia 



Middle N. Carolina 



N. 73° W. 



S. 72 W. 



S. 88 W. 



S. 84 W. 



N. 21 W. 



N. 83 W. 



S. 81 W. 



S. 78 W. 



S. 85 W. 



S. G5 W. 



S. 78 W. 



S. 78 W. 



S. 77 W, 



g=o 



S. 65° W, 



S. 69 W, 



S. 71 W, 



S. 77 VV, 



N. 68 W, 



N. 75 W, 



S. 81 W, 



S. 76 W, 



S. 42 W 



S. 61 W, 



S. 59 W, 



S. 51 W 



S. 64 W. 



S. 70° W. 



S. 70 W. 



S. 67 W. 



S. 65 W. 



N. 62 W. 



N. 81 W. 



25i i S. 61 W. 



39 J,; S. 68 W. 



S. 61 W. 



S. 60 W. 



S. 87 W. 



S. 86 W. 



N. 59 W 



See maps, PI. 8 and 11, and for the motion of clouds, and the velocity of the 

 winds, Plates 1 and 13. 



The different parts of this region agree very well as to mean direction of the wind 

 and even ratio of resultant : which generally amounts to about .30, Avhich in winter 

 is great enough for middle latitudes. In S. W. Illinois as well as in Kentucky the 

 winds are much more southerly in summer than in the other parts of this region ; 

 which is easily accounted for by the proximity of these States to the trans-Mississippi 

 region, where, as was shown before, the mean direction in summer is nearly due 

 south. As there are no mountains separating the two regions, the country on both 

 banks of the Mississippi being generally level, we must expect a gradual merging 

 of one into the other. It was shown above that E. Missouri and N. E. Arkansas 

 are also transition regions between the countries east and west of the Mississippi. 



Another exception is Toronto. The winds here were recorded with great care, 

 partly hourly during more than ten years, so that the difference presented cannot 

 be explained by shortness of the period. The ratio of resultant is great only 

 in winter, and it seems that a. great part of the then prevailing N. W. are land 

 winds. Lake Ontario is to the S. E. of Toronto For this reason we should 

 expect S. E. winds from the lake in summer, but it seems that they do not prevail 

 to a great extent, and that N. W. winds coming from over the colder waters of 

 Lake Huron also reach Toronto. The motion of upper clouds at this place, as 

 shown on Plate 1, nearly coincides with the course of the lower winds, being some- 

 what to the west in aU seasons, the difference is greatest in spring, 61°, and least 

 in summer, 7°. 



The mean direction is more northerly in spring than in other seasons. The 

 influence of the high pressure in the polar regions is seen in this, as also that of 

 the lakes, covered at this season with melting ice. In the other seasons the mean 

 direction is very nearly S. 67° W., or W. S. W. (See Plates 8 and 11.) 



To explain the accordance of observations in this region among themselves, it 

 must be remembered that it is comparatively old-settled, and the observations are 

 numerous, especially in New York, Pennsylvania and Ohio, and some of them 



