1046 
need for such analyses of storms covering a wide variety 
of magnitudes, durations, areas, storm types, seasons, 
and locations. The DDA values, were they placed on 
punch ecards, could be speedily correlated with many 
factors which have so far not been tested as to their 
significances to areal rainfall intensities. 
The use of punch-card techniques would facilitate 
extension of the work of Yarnell [84] and other writers, 
as regards rainfall probabilities. Addition of data from 
large numbers of DDA-analyzed storms would even- 
tually permit establishment of probabilities of occur- 
rence of areal rainfall intensities. 
Augmentation of Existing Rainfall-Reporting Net- 
works. Statistical studies as to correlations between 
point and areal rainfall depths should be undertaken 
with the objective, among others, of determining the 
proper density for rain-gage networks. It is likely 
that existing networks are acceptable for most purposes 
in some sections of the United States. In mountainous 
regions the network is still far too meager for determi- 
nation of effects of topography on rainfall. Over oceans 
and other large bodies of water—where special in- 
strumentation is required—there are essentially no ob- 
servations available for research. 
As suggested by Smith and Fletcher [20] in 1946, the 
use of radar for quantitative determination of pre- 
cipitation intensities between observing stations may 
have practical possibilities. Later investigations, such 
as those of Byers [2], tend to substantiate the idea. 
Radar has already proved its value in qualitative, short- 
range precipitation forecasting. Development of elec- 
tronic equipment to measure areal values of precipita- 
tion intensities would be of extreme value for both 
forecasting and planning. 
Physical Research. In theoretical hydrometeorology, 
the greatest need is for knowledge of the behavior of 
wind in space and time, over orographic and nonoro- 
graphic terrain, in synoptic situations favorable for 
peak rainfall intensities. Wind observations are required 
in great quantity in this connection, and physical 
reasoning regarding limiting conditions must be de- 
veloped. 
The equations of continuity and hydrostatics have 
been the principal theoretical relationships used in 
hydrometeorology. Exploration into the applicability 
of others, such as the equations of motion and of 
energy salninomsliins, is needed. 
Results of research in the field of ames tur- 
bulence can be turned to great practical use in hydro- 
meteorology. Intimately connected with the theory of 
turbulence are the problems of snow melt, evaporation, 
behavior of wind over rugged terrain, and the aggregate 
behavior of raindrops in convective cloud currents. - 
Some of these and other problems are amenable to 
treatment by the methods of statistical mechanics. 
As far as the field of hydrometeorology is concerned, 
there are two main goals toward which research should 
be directed. The first is the development of improved 
theoretical equations relating rainfall depths, averaged 
over area and through duration, with measurable in- 
HYDROMETEOROLOGY 
dependent variables. The other is the establishment of 
physically reliable methods of maximizing the rainfall 
through maximization of the variables, in combination, 
to which it is related. 
REFERENCES 
1. Brinn, G. W., “A Study of Quantitative Precipitation 
Forecasting in the TVA Basin.” U. S. Wea. Bur. Res. 
Pap. No. 26 (1946). 
2. Byers, H. R., and CotiaBorators, ‘‘The Use of Radar in 
Determining the Amount of Rain Falling over a Small 
Area.”’ Trans. Amer. geophys. Un., 29:187-196 (1948). 
3. Fiercurer, R. D., “Computation of Thunderstorm Rain- 
fall.” Trans. Amer. geophys. Un., 29:41-50 (1948). 
4. —— “A Relation between Maximum Observed Point and 
Areal Rainfall Values.” Trans. Amer. geophys. Un., 
31 :344-348 (1950). 
5. —— “‘A Hydrometeorological Analysis of Venezuelan Rain- 
fall.’ Bull. Amer. meteor. Soc.. 30:1-9 (1949). 
6. Fuuxs, J. R., ‘Rate of Precipitation from Adiabatically 
Ascending Air.” Mon. Wea. Rev. Wash., 63 :291-294 (1935). 
7. GLASSPOOLE, J., ‘“The Areas Covered by Intense and Wide- 
spread Falls of Rain.” Proc. Instn. civ. Engrs., 229 :137- 
166 (1930). 
8. Jenninecs, A. H., ‘‘World’s Greatest Observed Point Rain- 
falls.” Mon. Wea. Rev. Wash., 78:4—5 (1950). 
9. Joreensen, D. L., ‘‘An Objective Method of Forecasting 
Rain in Central California during the Raisin-Drying 
Season.’’ Mon. Wea. Rev. Wash., 77 :31-46 (1949). 
10. Kier, W. H., ‘“‘An Objective Method of Forecasting 5- 
Day Precipitation for the Tennessee Valley.’’ U. S. 
Wea. Bur. Res. Pap. No. 29 (1949). 
11. Konner, M. A., ‘“‘On the Use of Double-Mass Analysis for 
Testing the Consistency of Meteorological Records and 
for Making Required Adjustments.”’ Bull. Amer. meteor. 
Soc., 30:188-189 (1949). 
12. Ligut, P., ‘“‘Analysis of High Rates of Snow Melting.’’ 
U. S. Wea. Bur., Hydrometeor. Sect. Tech. Pap. No. 1 
(1941). 
13. McCormick, R. A., “Latitudinal Variation of Maximum 
Observed U.S. Rainfall Hast of the Rocky Mountains.” 
Trans. Amer. geophys. Un., 30:215-220 (1949). 
14. Miuuer, J. E., ‘‘Studies of Large Scale Vertical Motions of 
the Atmosphere.” Meteor. Pap., N. Y. Univ., Vol. 1, 
No. 1 (1948). 
15. Penn, S., ‘‘An Objective Method for Forecasting Precipi- 
tation Amounts from Winter Coastal Storms for Boston.” 
Mon. Wea. Rev. Wash., 76:149-161 (1948). 
16. Puatzman, G. W., ‘“‘Computation of Maximum Rainfall 
in the Willamette Basin.”” Trans. Amer. geophys. Un., 
_ 29:467-472 (1948). 
17. Russter, B. H., and Spreen, W. C., ‘“‘Topographically 
Adjusted Normal Isohyetal Maps for Western Colorado.” 
U.S. Wea. Bur. Tech. Pap. No. 4 (1947). 
18. SHanps, A. L., and AMMermaAN, D., ‘‘“Maximum Recorded 
U.S. Point Rainfall.” U. S. Wea. Bur. Tech. Pap. No. 
2 (1947). 
19. SHowauTer, A. K., ‘Rates of Precipitation from Pseudo- 
adiabatically Ascending Air.’”? Mon. Wea. Rev. Wash., 
72:1 (1944). 
20. Smiru, HE. D., and Fietcuer, R. D., 
Uses of Radar in Meteorology.” Trans. Amer. 
Un., 28:713-714 (1947). 
21. Sonor, S. B., “Computation of Depth of Precipitable 
Water in a Column of Air.’? Mon. Wea. Rev. Wash., 
67 100-103 (1939). 
“A Summary of the 
geophys. 
