THE COMPOSITION OF ATMOSPHERIC AIR 7 
oceans), but no experimental data are available to 
check this argument. 
Ozone during Thunderstorms. Dobson [e. 10] has ob- 
served many cases where the total O; increases during 
thunderstorms and during the passage of thunder- 
clouds. There can be little doubt that these changes 
occur in the tropospheric air and are caused by electric 
phenomena. A continuous measurement [10] during a 
thunderstorm gave no indication of any abnormal in- 
erease of O3; near the ground and on this occasion, at 
least, the O3-bearing air masses did not reach ground 
level. Other observers [13], however, found abnormally 
high O; values in ground air on some thundery days. 
Vertical Distribution of Ozone in the Troposphere. An 
increase of the O; content with height in the troposphere 
is shown by the data of Chalonge, Gétz, and Vassy [7], 
who found an average of 1.7 X 10-8 at Lauterbrunnen, 
Switzerland (800 m), and 3.0 X 10-8 at Jungfraujoch, 
Switzerland (3450 m). 
10 
AUG 21,1942 
'e) 
AUG 24,1942 
x AUG 19,1942 
(KM) 
HEIGHT 
) 
1 2 3 4 5 6 
OZONE IN 1078 PER VOL. 
Fig. 2.—Vertical distribution of ozone in the troposphere. 
(After Ehmert [c. 17].) 
Ozone determinations made in aircraft by Ehmert 
[c. 17] show a variety of features (see Fig. 2). In one 
case the air above cloud level has 03 contents which, 
__ if measured in volume per volume, are independent of 
height. This would be expected if the mixing ratio is 
kept constant by turbulence. Much less obvious is the 
fact that the O; content is high in cloudy regions and 
reaches a maximum just below cloud level. Regener 
[17] explains these maxima as produced by advection, 
which may sometimes be the case. However, the re- 
peated occurrence of stratified clouds near such an O3; 
maximum seems to indicate that under these conditions 
O; may be produced by phenomena of an electrical 
nature. 
Sulphur Dioxide (SO). The quantities of SO. found 
in air vary greatly according to the nearness ‘of towns 
and the turbulence of the air. To give a few examples: 
An average of 0.033 ppm was found at the Boyce 
Thompson Institute (about 15 miles from New York 
City); at Chicago an average of from 0.06 to 0.27 ppm 
was found in residential districts and from 0.4 to 0.5 
ppm in manufacturing districts. In the presence of Oz, 
air may be expected to be free of SOs. 
Nitrogen Dioxide (NO.). No systematic determina- 
tions of this constituent seem to have been made. This 
is largely because of the small quantity present in air 
and the difficulty of analysis. A very reliable method 
of NO» analysis in air, based on the use of 2:4 xylen- 
l-ol was used by Edgar and Paneth [c. 12]. From the 
fact that on a large number of days the NO, content 
found in this way was below the threshold of sensitivity 
(5 X 10-!), one is tempted to conclude that NOs is 
not a normal constituent of air. This may be due essen- 
tially to its high solubility in water. In large towns, 
however, where NO> occurs as a by-product from the 
combustion of nitrogenous matter, varying quantities 
up to 2 X 10-® were found by a number of authors. 
Ammonia (NH;). The presence of minute amounts 
of NH3 in atmospheric air over Michigan has been 
claimed by Mohler, Goldberg, and McMath [e. 15, 
Chap. 10] from absorption bands in the 2-y region. 
But, as Migeotte and Chapman [e. 15, Chap. 10] have 
pointed out, the 10.5-1 fundamental band of NH; is 
much more suitable for testing the presence of atmos- 
pheric NA3, and no evidence could be found in this 
region of absorption either above Flagstaff, Arizona, 
or above Columbus, Ohio. Moreover, NH; is very 
soluble in water and thus is not likely to be retained 
in the air for any lengthy period. 
Carbon Monoxide (CO). This gas was observed spec- 
troscopically by Migeotte [c. 1] over Columbus, Ohio, 
as well as on the Jungfraujoch (3580 m altitude) but, 
as none could be found by Adel over Flagstaff, Ari- 
zona [1], it is not yet certain whether it is a permanent 
constituent of the atmosphere. 
THE UPPER ATMOSPHERE 
The composition of air in the upper atmosphere is of 
considerable interest as an indicator of whether or not 
large-scale mixing of air masses takes place in the 
stratosphere. It is often assumed that the absence of a 
systematic temperature gradient in the stratosphere is 
incompatible with large-scale mixing. In the absence 
of turbulent mixing, however, diffusive separation of 
the gases should take place and the lighter gases should 
