ozone.plot <- ggplot(airquality, aes(x = Day, y = Ozone)) +
    geom_point() +
    geom_smooth() +
    facet_wrap(~ Month, nrow = 2)

solar.plot <- ggplot(airquality, aes(x = Day, y = Solar.R)) +
    geom_point() +
    geom_smooth() +
    facet_wrap(~ Month, nrow = 2)

wind.plot <- ggplot(airquality, aes(x = Day, y = Wind)) +
    geom_point() +
    geom_smooth() +
    facet_wrap(~ Month, nrow = 2)

temp.plot <- ggplot(airquality, aes(x = Day, y = Temp)) +
    geom_point() +
    geom_smooth() +
    facet_wrap(~ Month, nrow = 2)