Hurricane development is identified with a steady change from anticyclonic to cyclonic absolute vorticity.
A measure of absolute vorticity, the energy ratio, is introduced, and the structure of a number of hurricanes is discussed with its aid.
Simple cyclone-models are devised, and the characteristics of hurricane structure and growth elucidated with them. It is shown that the kinetic energy of a circular vortex may increase a hundredfold or more with maturity. The initial impetus comes in the early stage of absolute anticyclonic vorticity, but the main increase of energy accrues in the mature stage of cyclonic vorticity.
The ratio of the total area of a hurricane to the inner, eye, area is approximately 100 in all stages of growth.