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How Hurricanes Form <br /> Breeding Grounds <br /> Hurricanes are products of a tropical ocean and t <br /> a warm,moist atmosphere. Powered by heat l j. t T r <br /> from the sea,they are typically steered by the . <br /> surrounding deep layer(from the ocean's surface <br /> to 8 miles up)easterly winds,generally south <br /> r _ <br /> of 25°north latitude and by high-level westerly <br /> winds north of 25°north latitude. <br /> At <br /> R51c J.' Va.t'c O�ea a"'� Mldn"C OChin�� <br /> The Central Pacific hurricane season starts on r <br /> June 1 and continues through November 30, <br /> however tropical cyclones have been observed <br /> in the Central Pacific in every month except May. <br /> The peak of the season is July through October Jim August is the most active month,followed y' <br /> by July,September,and October.Over other t � <br /> parts of the world such as the western North <br /> Pacific,typhoons can occur year-round. <br /> NOAA <br /> Storm Structure <br /> Tropical cyclones begin as a disturbance,or an area of persistent and organized thunderstorm activity. The process by <br /> which a disturbance forms and strengthens into a hurricane depends on at least three conditions.First,a disturbance <br /> gathers heat and energy through contact with warm ocean waters.Next,added moisture evaporated from the sea <br /> surface powers the seedling tropical storm like a giant heat engine.Third,the seedling storm forms a wind pattern <br /> near the ocean surface that spirals <br /> HURRICANEair inward.Bands of thunderstorms <br /> AANDREW p NDREYY��r form,allowing the air to warm further <br /> and rise higher into the atmosphere. <br /> NWS NUANH RADAR If the winds at these higher levels <br /> y� <br /> Eye and ocean Aug�ust24,15T? are relatively light,this structure can <br /> •- w Y 0835 UlY W35 EDT remain intact and further strengthen <br /> Surface dBZ the hurricane. <br /> >48 <br /> 48 14urrlearre <br /> EyeWal I # 4z Rwieareh The center,or eye,of a hurricane is <br /> Division <br /> 40 relatively calm with sinking air,light <br /> Eyewall ;7 winds and few clouds.The most <br /> violent winds and rain take place in <br /> 19 the eyewall,the ring of thunderstorms <br /> 26 ...d immediately surrounding the eye.At <br /> r 23 the top of the eyewall(about 50,000 <br /> 18 N N � ,FL . feet),most of the air is propelled <br /> •� - ]�iNini,FL p p <br /> # {dig outward,increasing the air's upward <br /> fk,rr,.iin: I SHI x ]{�7km motion.Some of the air,however, <br /> � <br /> moves inward and sinks into the eye, <br /> Hurricane Andrew/NOAACategary S,Augusil4,1992 creating a cloud-free area. <br /> 5 <br />