SEVENTH ANNUAL MEETING 



89 



general the pressure decreases radially toward the center. At 

 the same time it is also evident that the pressure gradient is 

 steepest in the northwest and less toward the southeast. The 

 pressure distribution has a direct bearing on some of the re- 

 sults presented below. 



The arrows in figure 12, indicate the prevailing wind direc- 

 tions in the various tracts of the cyclone. They exhibit the 

 general spiral motion of the wind characteristic of cyclones. 

 Upon nearing the center the winds deviate increasingly toward 

 the right. The wind direction in the central tract possesses a 

 southwesterly component of motion. The lengths of the ar- 



Figure 14. Wind Velocity 



rows in figure 12 are proportional to the relative persistence or 

 constancy of the wind in the average direction. The con- 

 stancy of the wind shows two distinct variations. It in- 

 creases radially inward to a maximum and drops to its lowest 

 value at the center. This variation is evidently due to a sim- 

 ilar radial variation of the wind velocity shown in figure 13. 

 The greater inertia of the higher wind velocities renders them 

 less liable to be deflected by accidental causes. Secondly, the 

 constancy of the wind is greatest in the southwest and de- 

 creases toward the northeast. This is shown in figure 12, by 

 the three areas embracing wind directions whose constancy 

 values are, respectively 80-70 per cent; 70-60 per cent; and 

 60-50 per cent. The high constancy of the wind direction in 

 the southwest is probably due to several causes; the uninter- 

 rupted sweep of the wind over the level western prairies ; the 

 high wind velocity in this region as shown in figure 13; and 



