Tetens coefficients appear in a few meteorological/climatological models that I've been looking at,for example APSIM:
svp_A = 6.106 svp_B = 17.27 svp_C = 237.3
These same values appear in at least two other models, but I can't find any documentation about what they represent, or where they come from. What are these numbers?
Edit: Oroud, I. M., 2001, Dynamics of evaporation from saline water bodies uses these constants and references Tetens, O. 1930 "Uber einige meteorologische Begriffe." Z. Geophys. 6: 297-309, but that text doesn't appear to be available online, or in my university's library.