What are hurricanes?

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What are hurricanes?

Hurricanes are a type of “cyclone,” a word that has several uses in describing weather. In some parts of the Midwest, it means tornado; around the Indian Ocean, cyclone means hurricane. In meteorology, cyclone refers to any organized Northern Hemispheric wind system that rotates in a counterclockwise direction.

Madison’s winter snowstorms are cyclones. Because they originate in the middle latitudes of Earth, such storms are called mid-latitude cyclones. These storms are very common, with several occurring simultaneously around the hemisphere at nearly any time of year. Mid-latitude cyclones derive their energy from the difference between the polar and equatorial temperatures.

Hurricanes originate in the tropics and are called tropical cyclones. These storms are smaller than extratropical cyclones but usually more intense. Hurricanes derive their energy from the heat released as water vapor condenses to liquid water. Unlike extratropical cyclones, hurricanes are rather rare – averaging about 10 to 15 storms each year in the Atlantic basin.

Tropical cyclone formation is very sensitive to a number of environmental factors, including sea-surface temperature, vertical wind shear, and even dust from the Sahara desert! Madison has never experienced a hurricane but we do feel the effects of tropical cyclones. The devastating flooding events of August 2007 and June 2008 were both related to tropical cyclones that originally made landfall in the Gulf of Mexico.

Steven A. Ackerman and Jonathan Martin are professors in the Department of Atmospheric and Oceanic Sciences at UW-Madison, are guests on the Larry Meiller‘s WHA-AM radio show the last Monday of each month at 11:45 a.m.