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Chemical Oceanography, 4th Edition
particles and heavy precipitation occur when ice is present (typically at temperatures of
–5 to –20°C). Ice particles grow during collisions, and falling can result in the formation
of hail (if frozen) or rain (if it melts). The compounds dissolved in CCN can be made up of
dissolved gases (SO 2 , NH 3 , HCHO, H 2 O 2 , HNO 3 ) and salts ([NH 4 ] 2 SO 4 , NaCl, etc.). More
will be said about sulfur compounds.
5.2 Nitrogen Gases
The reactive nitrogen species in the lower atmosphere (Table 5.3) are NO, NO 2 , and HNO 3 .
These species are coupled by a series of reactions that cycle the various species. The reactions of these species are shown in Figure 5.10. The reaction of nitric oxide with hydroperoxyl radicals is of special interest:
NO + HO 2 → NO 2 + OH·
(5.18)
This reaction regenerates OH· from HO 2 . It also leads to the generation of ozone by the following:
NO 2 + hυ → NO + O·
(5.19)
1 s e c o n d
1 m
i n u t e
1 h o u r
1 d a y
1 y e a r
1 0 y e a r s
1 0 0 y e a r s
N 2 O
H 2
CH 3 CCl 3
CH 4
OCS
CO
O 3
CS 2
SO 2
HNO 3
NO 2
H 2 O 2
H 2 CO
HO 2
OH
Interhemispheric
Intrahemispheric
Atmospheric
lifetime
Atmospheric
mixing time
Figure 5.7
The atmospheric lifetimes of trace gases in the troposphere vary from 1 second to 100 years.