Atmospheric Vortex Engine

Frequently Asked Questions


6. Dust Devils, Water Spouts, Tornadoes, and Hurricanes

6.1 What is the source of energy of convective vortices?

The source of the energy for all convective vortices including: dust devils, waterspouts, tornadoes and hurricanes is the buoyancy of the air rising in the eyewall of the vortex. In the case of dust devils, where there is no condensation, the air near the ground can be 10 to 20°C warmer than the ambient air at the 10 m level and the rising air can be approximately 5°C warmer than the air through which it rises. In the case of water spouts and hurricanes, where there is condensation, the rising air becomes buoyant as it rises when its water vapor condenses and latent heat is released. The source of the energy of hurricane is widely recognized to be warm sea water. See: Total energy equation method for calculating hurricane intensity.  Recent high quality data permits precise calculation of hurricane intensity, see: Hurricane Isabel Intensity

The energy of tornadoes is sometimes attributed to the concentration of the turbulent energy of clouds and its transmission downward. Concentration of cloud turbulent energy would be contrary to the tendency of energy to deteriorate from more concentrated to more diffused. It is unlikely that the energy production in tornadoes is significantly different from that in other convective vortices.

The energy of a convective vortex comes from aloft but only from the buoyancy of the air rising in the vortex. The air rises in the wall of an annular tube. The force of buoyancy is transmitted downward in the annular tube in the same way as the buoyancy force is transmitted downward in the circular tube of the solar chimney.

The rotation of the air aloft is caused by convergence at the bottom of the atmosphere. The rotation of the air aloft is not the source of the rotation. The vortex intensifies as the thickness of the convergence layer decreases. Rotation can seem to occur aloft before it occurs near the ground because the intensity of the vortex increases as the thickness of the convergence layer decreases. The existence of a convective vortex requires a solid surface at the bottom of the vortex against which converging air can rub and thereby lose some of its angular momentum.

The pressure reduction and air velocity for all convective vortices can be accounted for in thermodynamic calculations by raising air approaching equilibrium with the underlying surface in an insulated vertical tube. The source of the energy is not just the pre-existing CAPE of the surface air; the heat content of ambient air is enhanced by heat transfer from the underlying surface. The reduced pressure at the base of a vortex enhances heat transfer between the air and the moist underlying surface.