A hurricane is a powerful storm that measures several hundred miles in diameter. Hurricanes have two main parts. The first is the eye of the hurricane, which is a calm area in the center of the storm.

Usually, the eye of a hurricane measures about 20 miles in diameter, and has very few clouds. The second part is the wall of clouds that surrounds the calm eye. This is where the hurricane's strongest winds and heaviest rain occur. Hurricanes are born over warm, tropical oceans, fueled by water vapor that is pushed up from the warm ocean surface, so they can last longer and sometimes move much further over water than over land. The combination of heat and moisture, along with the right wind conditions, can create a new hurricane.

Most Intense Hurricanes in the United States 1851-2005 (on Saffir-Simpson Hurricane scale: Cat. 1 = weak; Cat. 5 = devastating)

 Costliest Hurricanes in the United States (U.S. Mainland) 1900–2005.

• TS - Tropical storm intensity
• NOTE: Damages are listed in U.S. dollars and are not adjusted for inflation.

Once the winds of a tropical storm reach 74 miles per hour, a hurricane is born. Then, they are named in a special way. Hurricanes have been named after saints, girlfriends, years, and even first ladies (one was named "Bess" after President Harry Truman's wife). In 1979, though, the current system was adopted. When a tropical storm reaches wind speed of 39 miles per hour, the National Hurricane Center names the storm from one of the six lists below. After each list has been used, the six-year cycle begins again.

Six-Year List of Names for Atlantic Storms

Once a hurricane has caused great damage, its name is retired from the six-year cycle. The following names have been retired.

CAMILLE -Hurricane Camille is a bench mark in the American hurricane experience. Although Camille hit an area that had a relatively small population by today's standards - it still provided a horrific firsthand lesson of what a hurricane of maximum intensity can do to the man-made environment. Hurricane Camille remains the strongest storm to ever enter the US mainland on record. From a scientific perspective - Hurricane Camille represents bad luck, more than any meteorological extreme. However, unlike many of these super-storms that remine far out to sea, or weaken before making landfall - Camille struck land when at this rare intensity. The resulting property damage was so complete, that sections of the Mississippi coast seemed to vanish.

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KATRINA - Hurricane Katrina slammed into the U.S. Gulf Coast on Aug. 29, destroying beachfront towns in Mississippi and Louisiana, displacing a million people, and killing almost 1,800. When levees in New Orleans were breached, 80% of the city was submerged by the flooding. About 20% of its 500,000 citizens were trapped in the city without power, food, or drinking water. Rescue efforts were so delayed and haphazard that many were stranded for days on rooftops and in attics before help arrived. The city became a toxic pool of sewage, chemicals, and corpses, and in the ensuing chaos, mayhem and looting became rampant-about 15% of the city's police force had simply walked off the job. The 20,000 people who made their way to the Superdome, the city's emergency shelter, found themselves crammed into sweltering and fetid conditions. At a second shelter, the convention center, evacuees were terrorized by roaming gangs and random gunfire. Relief workers, medical help, security forces, and essential supplies remained profoundly inadequate during the first critical days of the disaster.

ANDREW - On Aug. 24, 1992, Hurricane Andrew slammed into South Florida, devastating Homestead, Florida City and parts of Miami, then continued northwest across the Gulf of Mexico to strike the Louisiana coastline. In all, the storm caused 15 deaths directly, 25 deaths indirectly and almost $30-billion in property damage. More than 250,000 people were left homeless; 82,000 businesses were destroyed or damaged; about 100,000 residents of south Dade County permanently left the area in Andrew's wake. Andrew also had a severe impact on the environment - it damaged 33% of the coral reefs at Biscayne National Park, and 90% of South Dade's native pinelands, mangroves and tropical hardwood hammocks. It also created 30 years worth of debris.

LAKE OKEECHOBEE, Fla. - The Great Okeechobee Flood--in the telling of Florida's hurricane history, no other hurricane disaster can compare to its toll of at least 1,836 dead in Florida, as well as another 1,575 in the Caribbean. At the time of the catastrophe, many in South Florida said the actual death count there was over 2,300; some said it may have been as high as 3,500. Whichever figure is correct, it ranks among the United States' worst natural disasters. It arrived on the coast near Palm Beach on the night of September 16, 1928, just two years after the Great Miami Hurricane, and like its predecessor, it cast its most sinister blow on those who lived on the southern edges of Lake Okeechobee.