BEHAVIOR PATTERNS OF NEW ENGLAND HAILSTORMS 
fore) 
60 
50 50 
40 40 
H max 
30 30 
k ft 
20 20 
STORM CLASS 
Lo HAIL REPEATER 10 
—--—- HAIL <20 MINUTES 
fe) 1 il — f] 1 1 ie) 
-150 -120 -90 -60 =30 fe) 30 60 90 120 150 
TIME AFTER FIRST HAIL — minutes 
Fiag. 6—The trends of echo top height in 20 hailstorms, related to time before or after first hail; the 
numbers identify the various storms; storms 1, 7, and 19 each produced several tornadoes 
330 
i 
STORM CLA8S H 420 
' 
HAIL REPEATER H 
—--- HAIL <20 MINUTES Ki 
\ 410 
' 
‘ 
1 
[enna rae 
-150 -120 -90 -60 -30 ° 30 60 90 120 150 
TIME AFTER FIRST HAIL —— minutes 
Fic. 7—The trends of median and maximum echo top height for the two 
groups of hailstorms, related to time before or after first hail 
and the attrition of falling hailstone size by melt- 
sity, at the same range, as the measured echo in- 
ing and break-up. 
The maximum echo intensities are expressed as 
the common logarithm of the maximum value of 
the equivalent radar reflectivity factor Z. The 
equivalent Z is defined as SN D®° (or volume con- 
centration of the sixth power of drop diameters, 
in mm°/m*) of small spherical water droplets 
which would return the same radar echo inten- 
tensity. The water droplets must be small enough 
to permit the use of the Rayleigh scattering ap- 
proximation, or about 2 mm or smaller in diam- 
eter for a radar wavelength of 3.2 em. Further 
discussion of the meteorological interpretation of 
equivalent Z is given by Donaldson [1958] 
Hail returns a considerably lower echo power 
than would be indicated by computing the Z of 
