Humidity variation during the flight

Here is the plot:

It was generate with the following code:

#Plot Humidity
plt.figure(figsize=(10,5))
plt.plot(df.index, df['hum'], label='Humidity')
plt.xlabel('Time of fight')
plt.ylabel('Humidity, %')

ax = plt.gca()  # Get the current Axes instance on the current figure
date_format = plt.matplotlib.dates.DateFormatter('%H:%M')  # Set format to hour:minute
ax.xaxis.set_major_formatter(date_format)
# plt.xlim(1000,6500)
# plt.ylim(720,1100)

ax.grid(axis='both', linestyle='--', linewidth=0.5)
plt.show()