A laboratory study was undertaken to measure variables responsible for the formation of air-entraining vortices with a slender air core extending from the free surface to the entry of a vertically inverted intake. The measured data indicate unique relations between radial and vertical scale for air-entraining vortices of the above description. From the measured data non-dimensional parameters governing the formation of such vortices were determined. The results, of this approach give universal curves which are independent of the intake geometry and the intake diameter. On this basis the measured data for horizontal intake, given in the previous paper [2], were re-evaluated and the results for both types of intake were compared. It has been found that the effect of the kinematic viscosity and the surface tension on the measured values become negligibly important when nondimensional parameters describing these effects is larger than 3 x 104. A value which is independent of the intake geometry and the intake diameter, but not on the type of intake. The bellmouth entry did not improve critical submergence heads for both types of intake as compared to those obtained for the simple pipe intake, but it, however, did improve entry flow conditions.