The paper invokes the power of computational fluid dynamics (CFD) for accurate determination of the detailed thermo-fluid-dynamics of natural convective flow around heated inclined plates, with an extensive experimental validation of the computed heat transfer results. The study provides fundamental physical insight through a comprehensive understanding of the behaviour of the contours of velocity, temperature and pressure as a function of inclination angle over the entire range from the vertical (gamma = 90 degrees) to the horizontal (gamma = 0 degrees). In particular, the present study documents, for the first time, qualitative and quantitative behaviour of the lift-off point at which the natural convective boundary layer converts into a free plume. Similarly, the details of the spatial evolution of the velocity profile and temperature profile in the plume as a function of the inclination angle of the plate are determined for the first time. It is shown how the relative importance of indirect pressure difference and direct buoyancy, as mechanisms of natural convection, changes as the inclination angle is gradually altered from the horizontal to the vertical. Through accurate computation (and ingenious representation) of the velocity, temperature and pressure fields at small intervals of the inclination angle, the subtle and complex thermo-fluid-dynamics in near-horizontal configurations is revealed. It is shown that the nondimensional lift-off distance changes from 0.5 (middle of the plate) to 0.9816 (nearly the trailing edge) as the angle of inclination is changed from 0 degrees to 15 degrees. It is established that as the inclination angle is increased gradually from the horizontal position, the value of average Nusselt number ( Nu) over bar initially decreases slightly, passes through a minimum point and then onward increases continuously up to the vertical position of the plate. (C) 2019 Elsevier Ltd. All rights reserved.