“…The weighting factor α generally depends on the measurement height, lag time, canopy structure and thermocouple size (Snyder et al, 1996;Spano et al, 1997aSpano et al, ,b, 2000Duce et al, 1998). Once determined, α is fairly stable, almost invariant and does not change from site to site regardless of weather conditions unless the canopy structure changes (Paw U et al, 1995;Snyder et al, 1996Snyder et al, , 2008Spano et al, 2000). A consistent α value of 0.5, using air temperature measurements conducted at canopy height, for coniferous forests, orchards, and maize canopies (Paw U et al, 1995); and 1.0 for short turf grass using measurements conducted at several heights above the canopy (Snyder et al, 1996) were reported to give best estimates of H compared to EC.…”