code: def plot_rh(self, rh, plot_range=None):
          
          # PLOT RELATIVE HUMIDITY
          if not plot_range:
              plot_range = [0, 100, 4]
          self.ax3 = fig.add_subplot(4, 1, 3, sharex=self.ax1)
          self.ax3.plot(self.dates, rh, 'g-', label='Relative Humidity')
          self.ax3.legend(loc='upper center', bbox_to_anchor=(0.5, 1.22), prop={'size': 12})
          self.ax3.grid(b=True, which='major', axis='y', color='k', linestyle='--',
                        linewidth=0.5)
          self.ax3.set_ylim(plot_range[0], plot_range[1], plot_range[2])
  
          self.ax3.fill_between(self.dates, rh, self.ax3.get_ylim()[0], color='g')
          self.ax3.set_ylabel('Relative Humidity\n(%)', multialignment='center')
          self.ax3.xaxis.set_major_formatter(mpl.dates.DateFormatter('%d/%H UTC'))
          axtwin = self.ax3.twinx()
          axtwin.set_ylim(plot_range[0], plot_range[1], plot_range[2])
docs: Required input:
              RH: Relative humidity (%)
          Optional Input:
              plot_range: Data range for making figure (list of (min,max,step))