SEVENTH ANNUAL MEETING 95 



relative humidity. In the winter time the warmer temperature 

 of the lakes might contribute to the general upward motion of 

 the air in cyclones with the consequent adiabatic cooling. 



That the presence of smoke bears a direct relationship to 

 cloudiness seems now to be an established fact. Such a rela- 

 tionship appears to be suggested in figure 18. It is seen that 

 the distribution of maximum cloudiness trends toward the 

 northeast. The action of smoke as a factor in producing this 

 may be stated as follows. Large volumes of smoke are poured 

 into the atmosphere by such manufacturing cities as Gary, Chi- 

 cago, Milwaukee, Minneapolis and many other cities lying 

 roughly within a quadrant northeast of Davenport. From the 

 figure it is seen that the maximum amount of cloudiness oc- 

 curs in Davenport when the city is so situated that it lies in the 

 path of the winds blowing over the smoke producing area. On 

 the other hand the quadrants northwest, southwest and south- 

 east of Davenport are relatively free from smoke and the 

 amount of cloudiness registered at Davenport when the winds 

 come from these regions is comparatively low. In order to be 

 reasonably certain that the matter here presented is a real cause 

 of cloudiness it would be necessary to actually count or estimate 

 by an appropriate method the number of particles of dust car- 

 ried by the atmosphere with the wind from the various direc- 

 tions. 



In the preceding paragraphs the author has described in part 

 the cyclonic distribution of weather elements for Davenport, 

 Iowa. The topics considered include : The barometric pressure; 

 wind direction ; wind velocity ; temperature ; vapour pressure ; 

 relative humidity; amount of cloudiness and the frequency of 

 precipitation. It is believed that the data here presented are 

 sufficient to show the character and to some extent the value 

 of the method employed, and justify a further application to 

 the method of other localities. 



The present description is incomplete. Other matters re- 

 ceiving attention are : the distribution of the various kinds of 

 clouds, thunderstorms, the direction of the higher air strata 

 and the seasonal distribution of the elements. The anti- 

 cyclones are being studied in a similar manner. The results of 

 a more complete survey of the problem will be given in a later 

 paper. 



In conclusion the author wishes to acknowledge with grati- 

 tude the assistance received from several sources. Mr. J. M. 

 Sherrier, Local Forecaster at Davenport, la., has offered help- 

 ful suggestions and courteously given access to the records of 



