HAIL STUDIES RELATING TO CLOUD PHYSICS 
State Water Survey and surface and upper air 
data of the U.S. Weather Bureau are also being 
studied. 
From these various types of data, information 
has been extracted on the location and extent 
of hailstorms, the movement of hailstorms, and 
the intensity of hailstorms in Illinois. 
Location and extent of storms—Days having 
greater than 20 paid losses were defined as hail- 
storm days. The number of hailstorm days from 
late May to early October during the period 
studied was 201 and ranged from 21 in 1952 to 
49 in 1956 [Stout, Blackmer, Changnon, and 
Huff, 1959]. Maps showing the location of hail 
damage to crops on each of these hailstorm days 
were plotted by marking the section in which 
hail damage occurred. A color code was used 
to designate the hour of hail occurrence when 
plotting the larger storms (greater than 150 
paid losses). Examples of the plotted maps 
showing the time and location of damaging hail 
are shown in Figures 2 and 3. 
371 
Figure 2 shows the locations where hail dam- 
aged crops on August 7, 1953. On this date hail 
destroyed one per cent of the crops in Illinois 
insured by CHIAA companies. The storm was 
widespread enough to affect three per cent of 
the crops in the state and the average loss to 
the crops affected was 33%. 
Areas of relatively continuous hail damage, 
shown on the map of August 7, 1953, will be 
referred to as ‘swaths.’ On this date there were 
six outstanding examples of these swaths, while 
other swaths which are smaller, or more scat- 
tered, are discernible. 
The locations of crop damage during the hail- 
storm of August 9, 1954, are shown in Figure 3. 
This storm had the largest number of paid losses 
during the 1952-57 period and is of particular 
interest because of the extreme length of the 
longest swath. This swath is at least 160 mi long, 
perhaps longer, since it may extend into Iowa. 
This storm destroyed one-half of one per cent 
of the crops insured by CHIAA companies in 
L.. 
Fie. 2—Loceation of hail on August 7, 1953 
