20 RADIATION 
of the available absorption-coefficient measurements 
for O. and O3; these absorption coefficients appear 
elsewhere in this Compendium.+* 
In equation (4), k, is the extinction coefficient; it 
includes the effect of both absorption and scattering. 
We can write 
(7) 
where ay is the absorption coefficient and s) is the scat- 
tering coefficient. In places where s, is small, such as 
at high elevations in the atmosphere, the transmission 
can be written approximately 
ky = a + Sy, 
Ih = Tx 10-7)", (8) 
where a, is the decimal absorption coefficient, and x 
is the path length through the absorbing gas. The 
amount of absorbed energy is 
Ta = 20m — DNAX = Zp — 10" )AX. —Q) 
In the case of ozone, computations of 7, have usually 
been based on the distribution of Zo, in a black body at 
6000K and give J, © 0.06 Jo. However, as indicated 
above, Jo, in the ultraviolet is considerably less than 
the value for a black body at 6000K. Therefore, J, is 
correspondingly smaller. If one accepts the 55-km V-2 
rocket and Smithsonian spectral measurements for Jo, 
then J, ~ 0.02 Jo [80]. Should further measurements 
verify still lower values of J, [85, 55], J. for ozone will 
have to be reduced even more. 
Obviously, the assumption of 6000K black-body in- 
tensities will also yield values for the absorption at 
specific altitudes in the ozonosphere which are too large. 
Thus computations such as Karandikar’s yield values 
that are too high for ultraviolet absorption [50]; Gowan 
[36] shows the effect of the lower absorption on the 
temperature of the air. 
Tn addition to its absorption in the ultraviolet, ozone 
absorbs small amounts of solar energy in other spectral 
regions. One of these, the Chappuis band, extends 
through the visible region from 4400 A to 7600 A and 
has a peak at 6000 A. The absorption coefficient is, 
however, so much smaller than that in the ultraviolet 
that, despite the much higher solar intensity, the total 
absorption in the Chappuis band is about 0.0071. 
In the infrared, absorptions are centered at 4.75 yn, 
9.6 uw, and 14.1 yw, but J isso small at those wave lengths 
that almost no energy is absorbed [50]. 
Spectral Absorption by Water Vapor. Among the at- 
mospheric gases, water vapor absorbs the largest 
amount of solar energy, and for the most part our 
knowledge regarding these water-vapor absorptions is 
due to Fowle [26, 27]. For \ > 0.9 u, energy is absorbed 
by water vapor with varying intensity in wide bands. 
Figure 4 shows the positions of these bands’ up to 
about 2.1 » and includes two bands (B and A) for 
4. Consult “Radiative Temperature Changes in the Ozone 
Layer” by R. A. Craig, pp. 292-302. 
5. The band labelled @ really includes three bands, namely, 
Q plus two small bands w; and w2. 
oxygen absorption; Fig. 5 shows the fractional trans- 
mission of energy in the band widths indicated by 
broken arrow-headed lines at the bottom of Fig. 4. 
In addition to the bands shown in Fig. 4, several weak 
lines appear below 0.7 uw, and very strong absorption 
bands appear beyond 2 w and particularly near 6 wu. 
WAVELENGTH (MICRONS) 
+ © + + y Wo) (e) ) ihe) (co) fo) fo) ho) 
i) o o eo) o + fo) Mm S ° a 
oO © tS o >) = XN {oo} fo) ea 
So © io) S) = = = a @ 
[e) ito) 
mM + co} 
—— 
fecunlbis 
— -<- - os nal 
a O8% p ® Vv a 
Fig. 4.—Loceation of absorption bands of oxygen (A and B) 
and of water vapor. (After Fowle [26].) 
rrAvIiIONAL TRANSMISSION 
0 ! 2 3 4 5 6 ie 8 
PRECIPITABLE WATER VAPOR, w (CM) 
Fie. 5.—Fractional transmission of solar radiation by 
water-vapor absorption bands as a function of precipitable 
water vapor. (After Fowle [26].) 
Fowle [27] measured the absorption in the regions 2-9 pz 
and some of his results are given in Table II. 
Fowle’s data were measured at atmospheric pressure. 
It has long been recognized that the fractional absorp- 
tion by a water-vapor band depends on the total pres- 
sure of the air; and laboratory pressure measurements 
on two water-vapor absorption bands have recently 
been made, although the two sets of measurements 
lead to somewhat different results. Drummeter and 
Strong [24] examined the maximum and minimum ab- 
sorption points in the 1.85-~ band and found that ab- 
sorption at the maximum points (1.82 » and 1.88 y) in- 
