KIMBALL: ATMOSPHERIC HAZINESS DURING 1912 271 



It appears that the haziness of these two periods is to be attri- 

 buted to three different causes, namely: 



1. The meteorological conditions, which are especially favor- 

 able for the formation of haze on the rear of anti-cyclonic areas. 

 A well defined anti-cylonic area crossed the region east of the 

 Rocky Mountains between June 6 and June 11. Another was 

 central over the Rocky Mountain region between June 17 and 

 June 21, and had passed eastward to the Atlantic ocean by June 

 24. 



2. Smoke from forest fires. There were extensive forest fires 

 in Yukon Territory, Canada, south of Dawson, during the latter 

 part of May, 1912, and in British Columbia about June 6, and 

 between June 11 and June 26. There were no important forest 

 fires in the United States during the month of June. 



3. Smoke or dust from Katmai Volcano. 



While it is impossible completely to separate the effects of these 

 three causes, it seems evident that the haze and smoke in British 

 Columbia on June 9-10, which was generally accompanied by 

 sulfur fumes, was at least in part of volcanic origin. The same 

 may also be said of the smoke and haze that was particularly 

 noticeable in the states of Washington, Montana, and Wyoming 

 on the same dates, coming, as it did, at about the time of the fall 

 of volcanic ash in the state of Washington. Several observers 

 state that the haze of the latter part of June, as well as that of 

 June 8-12, was a high haze, having some of the characteristics 

 of cirrus clouds, but lacking their fibrous appearance. At Madi- 

 son, Wisconsin, these cloud-like forms were first observed at 11 

 a.m. of June 8. If, as seems probable, they consisted of dust from 

 Katmai Volcano, their rate of transportation had been about 73 

 miles per hour. 



The haze appears to have been first observed in Europe between 

 June 20 and 27, altho there is evidence that it was present previous 

 to June 12. It was first observed in Algeria, Africa, on June 19, 

 altho it is probable that it affected the bolometric determinations 

 of solar radiation intensity as early as June 17. The characteris- 

 tics of the haze, and its effects, appear to have been practically the 

 same in Europe and in northern Africa as in North America. 



