3- The mean monthly temperature in °C from January to December in a year are 16.6,18.5, 23.3, 27.6, 28.4, 25.8, 24.4, 23.8, 23.5, 23.6, 20.2, 17.1. Calculate the annual potential

evapotranspiration using the Thornthwaite Equation. Why we should adjust the PET calculated by the Thornthwaite Equation?