Data frame with components: ozone, radiation, temperature, and wind.
Measurements of daily ozone con- centration (ppb), wind speed (mph),
daily maximum tempera- ture (degrees F), and solar radiation
(langleys) on 111 days from May to September 1973 in New York.  This
data frame is similar to air in S-PLUS (or library(data) in S), but
has a different definition for ozone (air contains cube-roots of
ozone).