<P> In recent times, tropical disturbances that reach tropical storm intensity are named from a predetermined list . Hurricanes that result in significant damage or casualties may have their names retired from the list at the request of the affected nations in order to prevent confusion should a subsequent storm be given the same name . On average, in the North Atlantic basin (from 1966 to 2009) 11.3 named storms occur each season, with an average of 6.2 becoming hurricanes and 2.3 becoming major hurricanes (Category 3 or greater). The climatological peak of activity is around September 11 each season . </P> <P> In March 2004, Catarina was the first hurricane - intensity tropical cyclone ever recorded in the Southern Atlantic Ocean . Since 2011, the Brazilian Navy Hydrographic Center has started to use the same scale of the North Atlantic Ocean for tropical cyclones in the South Atlantic Ocean and assign names to those which reach 35 kn (65 km / h; 40 mph). </P> <P> Tropical cyclones are steered by the surrounding flow throughout the depth of the troposphere (the atmosphere from the surface to about eight miles (12 km) high). Neil Frank, former director of the United States National Hurricane Center, used the analogies such as "a leaf carried along in a stream" or a "brick moving through a river of air" to describe the way atmospheric flow affects the path of a hurricane across the ocean . Specifically, air flow around high pressure systems and toward low pressure areas influences hurricane tracks . </P> <P> In the tropical latitudes, tropical storms and hurricanes generally move westward with a slight tendency toward the north, under the influence of the subtropical ridge, a high pressure system that usually extends east - west across the subtropics . South of the subtropical ridge, surface easterly winds (blowing from east to west) prevail . If the subtropical ridge is weakened by an upper trough, a tropical cyclone may turn poleward and then recurve, or curve back toward the northeast into the main belt of the Westerlies . Poleward (north) of the subtropical ridge, westerly winds prevail and generally steer tropical cyclones that reach northern latitudes toward the east . The westerlies also steer extratropical cyclones with their cold and warm fronts from west to east . </P>

Where does the names of the hurricanes come from