LONG-WAVE RADIATION 47 
lies exactly in the “window” of the water vapor and 
which therefore can contribute to the effectiveness of 
the outgoing radiation emitted by the earth’s surface 
despite the weak absorption and the small amount of 
ozone. Adel [2] measured the intensity of the solar 
spectrum at this wave length in an excellent experi- 
mental investigation and was able to detect the absorp- 
tion in this band. Its maximum is about 50 to 70 per 
cent. The old laboratory measurements by Hettner 
and collaborators [24] were made on large amounts of 
ozone under high pressure. From their absorption co- 
efficients and the normal amount of ozone in the atmos- 
phere the maximum absorption found at 9.6 uw is only 
14 per cent. This contradiction was explained by Strong 
[47], who made measurements with ozone under low 
total pressures. He was able to show that the supple- 
mentary atmospheric pressure greatly broadens the 
absorption lines of ozone, whereas an increased partial 
pressure causes only a minor broadening of these lines. 
It is for this reason that the absorptions measured in 
pure ozone without admixture of air are much too small 
in spite of large quantities of ozone. The application of 
the absorption values as measured by Strong leads to 
a maximum absorption at 9.6 u, equal to that found in 
gradient, namely from 6C per km im the troposphere 
to isothermal conditions in the stratosphere. By means 
of separate calculations of the individual bands of the 
three absorbers, water vapor, carbon dioxide, and ozone, 
he investigated the radiation balances and their de- 
pendence on barometric pressure and temperature at 
the tropopause. He found that im middle and high 
latitudes an equilibrium exists between the heating 
effeet of carbon dioxide and the cooling effect of water 
vapor; in the tropics, however, water vapor, because of 
its extremely small concentration, no longer has any 
effect. There, an equilibrium exists between the effects 
of carbon dioxide and ozone. At the great heights and 
the low temperatures of the tropical tropopause, how- 
ever, carbon dioxide has a cooling effect, ozone a very 
faint heating effect. This led Goody to the remarkable 
concept that radiative equilibrium always depends on 
the contrast between two different absorbers, and that 
in the tropics the participating media are different from 
those in middle latitudes. The quantitative bases of 
these computations appear to be still madequate. For 
this reason, verification would be most desirable. Also, 
it appears to this writer that the selection of the tropo- 
pause for these calculations is somehow not quite suit- 
Tas_Le IV. RapIATIONAL HEATING OF THE STRATOSPHERE (According to Oder [88]) 
h (km) 15 20 25 30 35 38 41 44 47 
Bity/at (deg © per day)............0.0020+ ait |) 0.6 208") Sa |) Ceo |) Creo | Cre) Ses 3.3 
epo/Gin (dep © oer hour)...-22.62-4-:.--+5- — —_ = — —1.8 =5.0 —7.2| —4.1 _ 
the solar spectrum. Though these processes are ex- 
plained for the 9.6-~ band, this is not true for the 14- 
band for which similar measurements are completely 
lacking. In this case we must depend on analogous con- 
clusions. 
Through numerous investigations we are well in- 
formed concerning the amount of ozone in the atmos- 
phere and its vertical distribution. Only recently were 
the optical determinations of this vertical distribution 
excellently confirmed by direct measurements. Pre- 
vious calculations of the radiation phenomena in the 
ozone (Gowan, Penndorf) are based on the uncorrected 
laboratory measurements of the absorption by Hettner. 
The results are therefore incorrect. Recently, a new 
calculation was made by Oder [88]. He uses values for 
the absorption coefficient which in each case give only 
an average for the whole band. This incorrectly distorts 
the absorption function, and his results are therefore 
apparently inaccurate. However, the numerical values, 
which are presented in Table IV, are noteworthy. 
At an altitude of about 40 km the emission of radiant 
heat produces a cooling of about SC per hour. It will 
not be very easy to explain what processes compensate 
for this large cooling, but they must be compensated 
somehow if the assumption that the temperature dis- 
tribution remains stationary is correct. Goody [20] 
made the most important contribution to the theory 
of radiation of the tropopause. He assumed that in this 
region a discontinuity exists in the vertical temperature 
able because of the peculiarities of radiative processes 
at points of discontinuity in the temperature gradient. 
However, it is difficult to suggest altitudes that would 
be more suitable for such computations.° 
Suggestions for Future Research 
Though the foregoing exposition touched only briefly 
on the experimental foundations, it has nevertheless 
been shown that the most important lines along which 
research must now proceed are of an experimental or 
observational nature. The following appear to the au- 
thor to be of particu’ar importance: 
1. Absorption or emission of water-vapor layers of 
limited thickness must be checked by laboratory and 
free-air experiments. The available measurements seem 
insufficient to explain the variation with temperature 
that results from the variation of the observed atmos- 
pheric radiation. Such measurements are a very impor- 
tant basis for radiation diagrams and for all conclusions 
drawn from them regarding the free atmosphere. 
2. Long-wave radiation, particularly in the free at- 
mosphere, must be measured. Since there are filter 
substances available which are not only very good in 
the long-wave range but which are uniform for all wave 
lengths [25], there should be no basic difficulty in con- 
5. (Note added July, 1950.) A recent investigation by Plass 
and Strong [40] may clarify this problem. However, only an 
abstract of this work has been published thus far, 
