368 DONALDSON, CHMELA, AND SHACKFORD 
volume in the stratosphere with time during the 
course of one of the tornado storms suggests a 
progressive modification of the low stratosphere 
in the vicinity of the storm, allowing easier pene- 
tration by the storm tops during the latter part 
of the storm life. 
Acknowledgments—The authors are deeply ap- 
preciative of the helpful criticism and many sug- 
gestions furnished by David Atlas. We are also 
appreciative of the constructive criticism of Ed- 
win Kessler. We are pleased to record our grati- 
tude to the volunteer thunderstorm observers of 
New England, whose many excellent reports have 
made this study possible. 
REFERENCES 
BeckwitH, W. B., Analysis of hailstorms in the 
Denver network, 1949-1958, this volume, pp. 348— 
353, 1960. 
Donatpson, R. J., Jr., Vertical profiles of radar echo 
reflectivity in thunderstorms, Proc. Seventh 
Weather Radar Conf., B 8-16, 1958. 
Donatpson, R. J., Jr., Analysis of severe convective 
storms observed by radar, II, J. Met., 16, 281-287, 
1959. 
Dovatas, R. H., Observations of Alberta hailstorms, 
First Conference on Cumulus Convection, Ports- 
mouth, N. H., May 19-22, 1959. 
Douatas, R. H., ann W. Hirscurep, Studies of Al- 
berta hailstorms, 1957, Sci. Rep. MW-27, Stormy 
Wea. Res. Group, McGill Univ., 79 pp., 1958. 
Lupuam, F. H., The hail problem, Nubila, 1, No. 1, 
Verona, Italy, 96 pp., 1958. 
Markus, J. S., Recent developments in studies of 
penetrative convection and an application to hur- 
ricane Cumulonimbus towers, First Conference 
on Cumulus Convection, Portsmouth, N. H., 
May 19-22, 1959. 
Newton, C. W., Morphology of thunderstorms and 
hailstorms as affected by vertical wind shear, 
this volume, pp. 339-347, 1960. 
Rype, J. W., The attenuation and radar echoes pro- 
duced at centimetre wavelengths by various me- 
teorological phenomena, Meteorological factors 
in radio wave propagation, Physical Society, Lon- 
don, 1946, pp. 169-189. 
Srout, G. E., R. H. Brackmer, Jr., 8. A. CHancnon, 
Jr. ano F. A. Hurr, Preliminary report on The 
Hail Hazard in Illinois, Illinois State Water Sur- 
vey, 33 pp., 1959. 
Vonnecut, B., anp C. B. Moore, Giant electrical 
storms, A. D. Little Co., Cambridge, Mass., 21 
pp. 1958 (unpublished). 
WeickMann, H., Observational data on the forma- 
tion of precipitation in Cumulonimbus clouds, 
Thunderstorm Electricity, Univ. Chicago Press, 
pp. 66-138, 1953. 
Discussion 
(Note: Discussion of this paper is combined with those of the preceding and following papers 
at the end of the following paper.) 
