Actual evaporation is calculated by means of an advection‐aridity complementary model which requires, as input, the meteorological data used in classical combination models. The main advantage of the model is that it does not require site‐specific calibration. The advection‐aridity formulation presented here includes the effect of atmospheric stability, which can be important to describe the diurnal evaporation variation, and a theoretical model of the scalar roughness height. A parameterization for advection over the surface of interest is incorporated which allows the model to be used for a wide range of natural conditions. The model was found to give good agreement with evaporation measurements obtained with a large sensitive lysimeter over a bare soil field.