JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. Ill MAY 19, 1913 No. 10 



METEOROLOGY. — The unusual atmospheric haziness during the 

 latter part of 1912. H. H. Kimball, Weather Bureau. 



In a previous paper^ it has been shown that when first observed 

 at Mount Weather on June 10, 1912, the haziness did not differ 

 materially from that usually observed on the rear of anti-cyclonic 

 areas, except in its unusual density. Subsequently,^ after the 

 haze had continued almost uninterruptedly for over two months, 

 it was thought that dust from Katmai Volcano, in Alaska, had 

 added its hazing effect to that of purely meteorological origin. 

 A careful compilation of all available observational data relative 

 to unusual haziness or smokiness or decreased atmospheric trans- 

 parency, during the latter part of 1912, was at once undertaken. 

 The results, of which the following is a summary, will be found 

 in greater detail elsewhere.^ 



Observational data. The observations have been derived from 

 the following sources: 



1. Descriptive papers and notes in various scientific journals. 



2. Extracts from the meteorological reports for June, 1912, of the 

 cooperative observers of the U. S. Weather Bureau. 



3. Rephes to a circular letter dated December 7, 1912, addressed to 

 officials in charge of Weather Bureau Stations, and requesting copies of 

 all notes made in the Daily Local Record since June 1, 1912, relative to 



1 This Journal, 2, 402, 1912. 



2 Bull. Mt. Weather Observatory, 5, 161. 



' The effect upon atmospheric transparency of the eruption of Katmai Volcano. 

 Monthly Weather Review. January, 1913. The effect of the atmospheric tur- 

 bidity of 1912 upon solar radiation intensities and skylight polarization. Bull. 

 Mt. Weather Observatory 5, pt. 5. 



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