Experiments for air flowing upward in a Vertical circular tube were conducted for heating rates causing significant property variation in primarily forced convection. Two entry Reynolds numbers were employed, concentrating on three heating rates of q(i)(+) = q(w)"/Gc(p,) (in) T-in approximate to 0.0018, 0.0035 and 0.0045, to give conditions considered to be ＇turbulent＇, ＇subturbulent＇ and ＇laminarizing＇. In addition to variation of integral parameters, results include the mean velocity and temperature distributions-needed to guide development of advanced turbulence models for this situation. However, comparison to a simple approach-a modified version of the van Driest model-shows useful agreement.