THE DUSTFALL OF FEBRUARY 13, 1923 1 
By Alexander N. Winchell, Professor of Mineralogy and Petrology, Uni¬ 
versity of Wisconsin, and Eric R. Miller, Meteorologist, United States 
Weather Bureau 
INTRODUCTION 
DESCRIPTION OF THE DUSTFALL 
Dustfalls seem relatively rare. Dur¬ 
ing the past six years the catch of every 
rain and snow at Madison, Wis., has 
been filtered, but samples from only 
four dustfalls have been obtained. 
Except in those four well-defined cases, 
the solid precipitates were very small 
in amount and consisted mostly of 
The dustfall of February 13, 1923, 
differed from the other three in that 
the region of deflation extended nearer 
to Madison, Wis., on this occasion. 
The dust fell at Madison in a snowfall 
of 0.6 inch which fell as the center of 
Low No. IV passed over. Figure 1 
shows the track of this storm. At Madi- 
Fin l.—Shaded area shows extent of snow cover at 7 p. m. February 12, 1923. Forked line with arrow¬ 
heads shows paths of centers of dust-bringing whirlwind. Numbers within small circles show maximum 
wind velocities in miles per hour. The day of occurrence was February 13 except at places marked 12 below 
the circle, where it occurred on the 12th. The closed line includes all places where the maximum velocity 
exceeded 40 miles per hour 
soot and other products of combustion. 
Reports on the dustfall of March 9, 
1918, and of a second on March 19, 
1920, have already been published by 
the writers (11, 12)? The third dust¬ 
fall, on February 13, 1923, is discussed 
in the present paper. The unusually 
complete samples afforded by the fourth 
dustfall, on March 29, 1924, are now 
being prepared for analysis. 
son the accompanying precipitation 
lasted from 1.30 to 4.30 p. m. The 
direction and velocity of the wind dur¬ 
ing this time were as follows: Mile8 
Time (p. m.) Direction per hour 
1 to 2. Northeast.. 5 
2 to 3. West- 7 
3 to 4.. Northwest_ 10 
4 to 5. West_27 
Velocities averaging 25 miles per hour 
continued for the following 24 hours. 
1 Received for publication May 6, 1924—issued January, 1925. 
2 Reference is made by number (italic) to “Literature cited,” p. 450. 
Journal of Agricultural Research, 
Washington, D. C. 
( 443 ) 
Vol. XXIX, No. 9 
Nov. 1, 1924 
Key No. Wis.-27 
