The raleigh.temp data frame has 480 rows and 3 columns. Each year has 12 rows of data, one for each month. The measurement is likely to be the average of the average daily temperature, where the average daily temperature = (daily high+daily low)/2.
A data frame with 480 observations on the following 3 variables.
: temperature = (daily high+daily low)/2
: the month the measurements were taken during
: the year the measurements were taken during