420 
lations. It would be easy to extend this list of new prob- 
lems considerably. But it may suffice to say that the 
perturbation method almost invariably will have to 
be used to get a first insight into these problems because 
in all branches of mathematical physics linear differen- 
tial equations are the only ones which can in general 
be dealt with successfully. Even in those deplorably 
rare instances when nonlinear problems can be handled, 
the linearized problem and its solution gives a valuable 
and helpful guidance in the solution of the nonlinear 
problem. 
REFERENCES 
1. BserKENEs, V., “‘On Quasi Static Wavemotion in Barotropic 
Fluid Strata.” Geofys. Publ., Vol. 3, No. 3 (1923). 
2. —— “Die atmosphirischen Stérungsgleichungen.”’ Beitr. 
Phys. fret. Atmos., 13:1-14 (1927). 
3. —— “Uber die hydrodynamischen Gleichungen in La- 
grangescher und Eulerscher Form und ihre Linearisie- 
rung fiir das Studium kleiner Stérungen.”’ Geofys. Publ., 
Vol. 5, No. 11 (1929). 
4. —— and others, Physikalische Hydrodynamik. Berlin, J. 
Springer, 1933. 
5. CHarney, J. G., ‘On the Seale of Atmospheric Motions.”’ 
Geofys. Publ., Vol. 17, No. 2 (1948). 
6. —— and Ettassen, A., ‘‘A Numerical Method for Pre- 
dicting the Perturbations of the Middle Latitude Wester- 
lies.”” Tellus, Vol. 1, No. 2, pp. 38-54 (1949). 
7. Craic, R. A., ‘A Solution of the Nonlinear Vorticity 
Equation for Atmospheric Motion.’ J. Meteor., 2:175- 
178 (1945). 
8. Extassgn, A., “The Quasi-static Equations of Motion with 
18. 
19. 
20. 
21. 
DYNAMICS OF THE ATMOSPHERE 
Pressure as Independent Variable.”’ Geofys. Publ., Vol. 
17, No. 3 (1949). 
. Haurwirz, B., ‘Uber Wellenbewegungen an der Grenz- 
flache zweier Luftschichten mit linearem Temperaturge- 
fille,’ Beitr. Phys. fret. Atmos., 19:47-54 (1932). 
.—— ‘Uber die Wellenlinge von Luftwogen,” 2. Mitt. 
Beitr. Geophys., 37-16-24 (1932). 
. — “The Motion of Atmospheric Disturbances on the 
Spherical Earth.”’ J. mar. Res., 3:254-267 (1940). 
. JEFFREYS, H., ‘‘On the Dynamics of Wind.” Quart. J. R. 
meteor. Soc., 48:29-47 (1922). 
. Lams, H., ‘On Atmospheric Oscillations.” Proc. roy. Soc., 
(A) 84:551-572 (1910). 
. LANGWELL, P. A., “‘Forced Convection Cell Circulation in 
Clear Air.’”? Trans. Amer. geophys. Un., 32:7-14 (1951). 
. Neamran, 8. M., “‘The Motion of Harmonic Waves in the 
Atmosphere.” J. Meteor., 3:53-56 (1946). 
. QuenEy, P., “‘Adiabatic Perturbation Equations for a 
Zonal Atmospheric Current.” Tellus, 2:35-51 (1950). 
. RomBaxts, S.. “Uber ein Integral der nichtlinearen hydro- 
dynamischen Gleichungen und seine Anwendung in der 
Meteorologie.”’ Z. Meteor., 2:241—-244 (1948). 
Rosssy, C.-G., and CoLtuaporartors, ‘Relation between 
Variations in the Intensity of the Zonal Circulation of 
the Atmosphere and the Displacements of the Semi- 
permanent Centers of Action.” J. mar. Res., 2:38-55 
(1939). 
Sonpere, H., ‘‘Integrationen der atmosphirischen Sté- 
rungsgleichungen.”’ Geofys. Publ., Vol. 5, No. 9 (1928). 
—— ‘Uber die freien Schwingungen einer homogenen 
Flissigkeitsschicht auf der rotierenden Erde. I.” Astro- 
phys. norveg., 1:237—-340 (1936). 
Srarr, V. P., and Nerpurcer, M., ‘Potential Vorticity as 
a Conservative Property.” J. mar. Res., 3:202-210 (1940). 
