366 
ro) 
in mm 
% OCCURRENCE /CATEGORY WIDTH 
a 
fo} 
10 20 30 40 50 60 
DIAMETER — mm 
(he 2" 
Fig. 16—Occurrence of maximum hail size 
100 
80 
x 60 
| 
> 
o 
Zz 40 
= CUMULATIVE FREQUENCY OF OCCURRENCE 
Y OF MAXIMUM HAIL SIZE 
“ 20 n= 290 
10 20 30 40 50 60 70 80 
DIAMETER — mm 
" 2" 3" 
Fie. 17—Cumulative frequency distribution of 
maximum hail size 
three summers, 317 hail reports were received 
with one or more useful bits of information about 
the hailstones or their timing. The most frequent 
maximum size reported (Fig. 16) is %4 inch. The 
median is 7 mm, and less than five per cent of the 
reported hail equals or exceeds one inch in diam- 
eter (see Fig. 17). Hail sizes in New England are 
considerably smaller than those found to the east 
of the Rockies by Beckwith [1959] and by Doug- 
las and Hitschfeld [1958], but are comparable to 
those observed in Illinois by Stout and others 
[1959]. 
Information on size distribution within a given 
hailfall was received from a limited number of 
observers who reported maximum and ‘average,’ 
or maximum and minimum sizes (Fig. 18). The 
representative size distribution is narrow. A typi- 
DONALDSON, CHMELA, AND SHACKFORD 
cal max/min size ratio is 2, with nearly 90% of 
all distributions within a spread of 3. One should 
expect the size range to be relatively narrow at 
the ground because of the greater melting rate of 
small stones during their fall. 
Many observers reported hail durations (Fig. 
19), but a certain favoritism was evident for 
multiples of five minutes. A three-minute run- 
ning mean smoothed out this periodicity some- 
what. The median hailfall duration is three to 
four minutes. The five-minute periodicity was 
also a strong feature of the timing relationship 
between the beginning of hail and heavy rain 
(Fig. 20). In a very few cases hail began falling 
before the heavy rain, but in the median case 
100 
CUMULATIVE FREQUENCY 
OF 
OCCURRENCE OF HAIL SIZE RANG 
80 
60 
40 
FREQUENCY — % 
20 
| 3 5 it 9 I 
RATIO 
Fig. 18—Cumulative frequency distribution of 
size range in a hailfall 
50 
40- 
(et) 
fo} 
OCCURRENCES 
n 
fe} 
° 5 10 15 20 25 
HAIL DURATION — minutes 
Fie. 19—Frequeney of occurrence of hailfall 
durations 
