WASHINGTON, Sept. 2 (Xinhua) -- Hurricane Dorian made landfall in the Bahamas on Sunday as a powerful Category 5 storm with maximum sustained winds of 185 miles (298 km) per hour, according to the National Hurricane Center's 8 p.m. ET (2400 GMT) advisory.
Hurricanes, also known as "typhoons" in Southeast Asia and "cyclones" in the Indian Ocean and Australia, are large rotating storms with high speed winds that form over warm waters in tropical areas. They have sustained winds of greater than 74 miles (118 km) per hour.
Hurricanes form near the equator over warm ocean waters, when sea-surface temperatures exceed 27 Celsius degrees and the surrounding atmosphere is calm. As warm moist air rises, cooler air would be drawn into the low-pressure area below, a positive feedback process is made. A hurricane is thus driven by heat energy, combined with the rotation of the Earth.
According to the speed of their sustained winds, hurricanes are categorized in five levels. As winds increase to a sustained speed of 74 miles (119 km) per hour, a tropical storm becomes a Category 1 hurricane. It becomes Category 2 with sustained winds at 96 miles (154 km) per hour, Category 3 at 111 miles (179 km) per hour, Category 4 at 130 miles (209 km) per hour, and finally the most devastating variety, Category 5, when wind speeds exceed 157 miles (253 km) per hour.
Meteorological records showed more than 290 Atlantic tropical cyclones have produced hurricane-force winds in the United States. Florida was affected by more hurricanes than any other state. The following is a list of major hurricanes hitting the United States in recent decades.
-- Hurricane Katrina
Hurricane Katrina in 2005 was the record costliest hurricane with property damages of 125 billion U.S. dollars. At least 1,800 people died in the hurricane and subsequent floods. This Category 5 hurricane was the third major hurricane of the record-breaking 2005 Atlantic hurricane season.
-- Hurricane Sandy
Hurricane Sandy, also known as Superstorm Sandy, was the deadliest and most destructive hurricane of the 2012 Atlantic hurricane season. It hit the highly populated areas of New York and New Jersey, resulting in 286 deaths and nearly 70-billion-dollars in damage.
-- Hurricane Harvey
The Harvey Hurricane of 2017 is tied with 2005's Hurricane Katrina as the costliest tropical cyclone on record, causing 125 billion dollars in damage and at least 107 confirmed deaths. Due to the extensive damage, the name "Harvey" was retired and won't be used for another Atlantic tropical cyclone.
-- Hurricane Irma
Hurricane Irma was the most powerful Atlantic hurricane in history. This Category 5 storm made landfall on Barbuda in September 2017. It caused 129 deaths and the evacuation of 6.5 million people.
-- Hurricane Maria
Hurricane Maria was a deadly Category 5 hurricane that made landfall in Dominica, the U.S. Virgin Islands, and Puerto Rico in September 2017. Over 3,000 people were killed in the storm. Total losses from the hurricane are estimated at upwards of 91.61 billion dollars, ranking it as the third-costliest tropical cyclone on record.
