92 



ILLINOIS ACADEMY OF SCIENCE 



The distribution of temperatures within the cyclone is shown 

 in figure 15. The average temperatures for the various tracts 

 are inscribed within the small circles. The temperature distri- 

 bution is also represented graphically by the shaded areas which 

 enclose temperatures ranging from 60-50, 50-40, and 40-30 re- 

 spectively. The highest temperatures are seen to prevail in 

 the southeast quadrant of the cyclone. This is due to the south- 

 erly direction of the winds in that region. The low tempera- 



LEGEND 



■■ 90 -8 5 

 HI 85-80 

 EM 80-75 

 CZ2 75-70 



Figure 17. Relative Humidity 



tures in the northwest are produced by the cool winds from the 

 north. 



The distribution of vapour pressure is similar to that of the 

 temperature. This is seen by comparing figures 15 and 16. 

 The vapour pressure is greatest in the southeast and least in 

 the northwest. The vapour pressure also increases radially 

 toward the center. The similarity of the vapour pressure and 

 temperature distribution is a necessary consequence of the fact 



