HAILSTORMS IN THE DENVER NETWORK 
MB 
tt 1 
1 a = 
570) =60) =S0) =40°-30° =20 -=10 fe) 10 20 ~=30' °c 
Fic. 9—Mean sounding for 18 hail days in 1956, 
1957, and 1958; solid line is temperature distribu- 
tion, broken line is dew point curve, and dash-dot 
line is the parcel adiabat; mean tropopause height 
is at 134 mb (approximately 45,000 ft) 
investigation to the tropopause, it is found that 
the mean lapse rate of the 18 soundings is steep 
enough to produce a positive energy area from 
the LCL to about 35,000 ft. 
Soundings published by Douglas and Beckwith 
[1958] for some of the larger hail situations oc- 
curring in Alberta in 1957 are mainly in agree- 
ment with this Denver mean except for the 
tropopause altitude which is lower in Canada in 
accordance with the normal latitudinal differ- 
ence. 
Although no firm conclusions may be drawn 
on this limited sampling, it appears that on days 
with hail, the height of the tropopause at Denver 
is, on the average, lower than on non-hail days. 
Other work—In the attempt to develop new 
methods of analysis of hailstorms and in re- 
viewing the work of others in this field, one can- 
not overlook the strong suggestion that the 
393 
make-up of thunderstorms in general and hail- 
storms in particular, involves an important in- 
gredient not recognized today. Whether or not 
this involves space charges, for example, or un- 
knowns in cloud nuclei is something for the cloud 
physicists to determine. 
As of today, the hailstorm remains as a prob- 
lem for the farmer and for the property owner. 
In aviation, hail is less of a hazard now, thanks 
to airborne radar. But the forecaster must con- 
tinue to be alert for these developments as air- 
craft now flying near the tropopause appear to 
be exposed to an even higher proportion of large 
hailstones than experience up to now would dic- 
tate. 
Acknowledgments—The author again wishes 
to express his gratitude to the corps of unofficial 
observers who have cooperated since 1949 in the 
reporting of hailstorms in the Denver area, and 
without whose help this project would not have 
been possible. 
REFERENCES 
BecxwitH, W. B., Hail observations in the Denver 
area, United Air Lines Met. Circ. 40, 41 pp., 
April 1, 1956. 
Dovcias, R. H., ano W. Hirscureup, Studies of 
Alberta hailstorms, 1957, McGill University, 
Stormy Weather Res. Group, Sci. Rep. MW-27, 
79 pp., May 1958. 
Dovatas, R. H., anp W. B. BeckwirH, Hailstorm 
features determined from studies in Alberta and 
Colorado, paper presented at American Mete- 
orological Society Conference on Practical Prob- 
lems of Meteorology, Sept. 24, 1958, unpublished. 
Fawsusu, E. J., anp R. C. Minter, A method for 
forecasting hailstone size at the Earth’s surface, 
Bul. Amer. Met. Soc., 34, 235-244, 1953. 
Harrison, H. T., ano W. B. BeckwitH, A re-ex- 
amination of hail patterns over western United 
States, United Air Lines Met. Cire. 35, 27 pp., 
March 15, 1950. 
Harrison, H. T., anp E. A. Post, Evaluation of C- 
Band (5.5 em) airborne weather radar, United 
Air Lines Spec. Rep., 108 pp., March 1, 1954. 
Strout, G. E., R. H. Brackmmr, 8. A. CHANGNON, AND 
F. A. Hurr, The hail hazard in Illinois, Prelim. 
Rep. Ill. State Water Survey, 33 pp., January 
31, 1959. 
Discussion 
(Note: Discussion of this paper is combined with those of the two following papers at the 
end of the second following paper.) 
