EFFECTS OF VERTICAL WIND ON STORMS 345 
Ae First echo 
Be 
FORT WORTH 
(Radar) 
MIDLOTHIAN ce 
waco @ 
(Radar) 
STORM 
MOVEMENT 
KN Heavy rain, small hail 
\\ Damaging winds, large hail 
e@ BREMOND 
Fig. 6—Path of heavy hail- and rainstorm near Fort Worth, Texas, April 
21, 1958, from Hamilton [1958]; (inset) vector storm velocity compared with 
winds aloft 
analyzed, the hypothesis presented above appears 
to account for the gross behavior of rainstorms. 
That it does not satisfactorily account for all de- 
tails is shown by the fact that in the second case 
above, as well as in several published radar ob- 
servations of tornadoes, the most intense phe- 
nomena apparently occurred somewhat upwind, 
rather than on the direct right flanks of the storms 
concerned. Understanding of such phenomena 
must come eventually from increasingly detailed 
observations, interpreted not only in terms of or- 
dinary thermodynamic processes, but also in the 
light of the interactions between storms and their 
environments. 
Further remarks on other studies—At the time 
of writing the above, I was not aware of highly 
pertinent remarks in some other studies. Dessens 
[1959] (who offers a different explanation) states 
that “the existence of a jet stream or at least of a 
very strong wind aloft is the sole factor that we 
have been able to isolate as very probably re- 
sponsible for the formation of destructive hail’; 
the relation to high winds aloft was also brought 
out by Wichmann [1951]. These studies emphasize 
that instability by itself does not completely ac- 
count for large hail formation. Small or medium 
Fic. 7—Winds in Fort Worth vicinity at 30,000 
and 5000 ft, 12h00m CST April 21, 1958 
