July and August (Fig. 2). During summer, O3 photolysis is at its
highest and the humidity is increased, so the photolytic reactions
involving the resultant OH radical lead to the formation of high
concentrations of RO2. Minimum values are seen during the winter
months, typically in December and January when the solar intensity
is diminished. Data obtained from the Southern hemisphere
station, Cape Grim, demonstrates an opposite but analogous seasonal
trend. Maximum and minimum values are recorded in June
and January, respectively (Fig. 2).