Published On:Monday, July 19, 2010

Tropical cyclones are named to provide ease of communication between forecasters and the general public regarding forecasts, watches, and warnings. Since the storms can often last a week or longer and  more than one can occur in the same basin at the same time, names can reduce the confusion about what storm is being described. According to Dunn and Miller (1960), the first use of a proper name for a tropical cyclone was by an Australian forecaster early in this century. He gave tropical cyclone names "after political figures whom he disliked. By properly naming a hurricane, the weatherman could publicly describe a politician (who perhaps was not too generous with weather-bureau appropriations) as 'causing great distress' or 'wandering aimlessly about the Pacific.'"

During World War II, tropical cyclones were informally given women's names by US Army Air Corp and Navy meteorologists (after their girlfriends or wives) who were monitoring and forecasting tropical cyclones over the Pacific. From 1950 to 1952, tropical cyclones of the North Atlantic Ocean were identified by the phonetic alphabet (Able-Baker-Charlie-etc.), but in 1953 the US Weather Bureau switched to women's names. In 1979, the WMO and the U.S. National Weather Service (NWS) switched to a list of names that also included men's names.

What is the origin of the name "hurricane"?

"Hurricane" is derived from 'Hurricane', the Carib god of evil.

Should I tape my windows when a hurricane threatens?

No, it is a waste of effort, time, and tape. It offers little strength to the glass and NO protection against flying debris. After the storm passes you will spend many a hot summer afternoon trying to scrape the old, baked-on tape off your windows (assuming they weren't shattered). Once a Hurricane Warning has been issued you would be better off spending your time putting up shutters over doors and windows.

Are we getting stronger and more frequent hurricanes, typhoons, and tropical cyclones in the last several years?

Globally, no. However, for the Atlantic basin we have seen an increase in the number of strong hurricanes since 1995. We have had a record 33 hurricanes in the four years of 1995 to 1999 (accurate records for the Atlantic are thought to begin around 1944). The extreme impacts from Hurricanes Marilyn (1995), Opal (1995), Fran (1996), Georges (1998) and Mitch (1998) in the United States and throughout the Caribbean attest to the high amount of Atlantic hurricane activity lately.

Why do tropical cyclones occur primarily in the summer and autumn?

The primary time of year for getting tropical cyclones is during the summer and autumn: July-October for the Northern Hemisphere and December-March for the Southern Hemisphere (though there are differences from basin to basin). The peak in summer/autumn is due to having all of the necessary ingredients become most favorable during this time of year: warm ocean waters (at least 26°C or 80°F), a tropical atmosphere that can quite easily kick off convection (i.e. thunderstorms), low vertical shear in the troposphere, and a substantial amount of large-scale spin available (either through the monsoon trough or easterly waves).

Why do tropical cyclones' winds rotate counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere?

The reason is that the earth's rotation sets up an apparent force (called the Coriolis force) that pulls the winds to the right in the Northern Hemisphere (and to the left in the Southern Hemisphere). So when a low pressure starts to form north of the equator, the surface winds will flow inward trying to fill in the low and will be deflected to the right and a counter-clockwise rotation will be initiated. The opposite (a deflection to the left and a clockwise rotation) will occur south of the equator.