Potential evaporation and “The complementary relationship”

It is shown that Morton's concept of a complementary relationship between actual and potential evaporation is in no way incompatible with Penman's concept of potential evaporation. A difference in terminology, with some lack of precision in the difinition of what was being kept constant, has led to an apparent, not a real, conflict. The conclusion is drawn that Morton's work provides a valuable extension of Penman's, leading to a method of calculating actual evaporation under the condition of a less than abundant water supply.