Hurricanes typically last from two to fourteen days. They tend to move from east
to west, at speeds between 10 and 30 mph. Their intensity is ranked on
a scale of 1 to 5 called the Saffir-Simpson scale. This scale measures
three types of activity: wind speed, air pressure, and storm surge. The
storm surge is a 50 to 100-mile-wide dome of water that sweeps across
the coastline near where a hurricane makes landfall.
You can see tropical cyclones in satellite pictures
of clouds taken from above the earth. But scientists still track tropical
cyclones by using airplanes. Only airplanes flying through the storm can
tell how big the storm is, how fast it is moving, and how strong its winds
How do they determine the "category"?
Category 3, 4, and 5 hurricanes are collectively referred to as intense
or major hurricanes. These intense hurricanes cause over 70% of the damage
in the United States, even though they account for only 20% of all hurricane strikes.
Check the chart below to see how scientists rate hurricanes
||Maximum sustained wind speed (mph)
||Minimum surface pressure (mb)
||Storm surge (feet)
How do they name the hurricane?
Every tropical cyclone is given a name when it becomes strong and dangerous.
The storm name is always used in all weather warnings. Using a name helps
people tell one storm from another and follow its movements.
Official storm trackers all over the world have lists of names ready.
The chosen hurricane names are used in a 6-year rotation, unless they're
See the official list of names from the National Hurricane Center: http://www.nhc.noaa.gov/aboutnames.shtml
Once the 21 names chosen each year have been used, the Greek alphabet
is used to name the storms.
Do you share a name with a famous historical hurricane?
Hurricane names are removed from the lists after they've been used for
a storm that was very strong or caused a lot of damage.
These names won't be used again:
- Allison, 2001; Agnes, 1972; Alicia, 1983; Allen, 1980; Andrew, 1992; Anita, 1977;
- Betsy, 1965; Beulah, 1967; Bob, 1991
- Camille, 1969; Carla, 1961; Carmen, 1974; Carol, 1965; Celia, 1970;
Charley, 2004; Cleo, 1964; Connie, 1955
- David, 1979; Dennis, 2005; Diana, 1990; Diane, 1955; Donna, 1960; Dora, 1964
- Edna, 1968; Elena, 1985; Eloise, 1975
- Fifi, 1974; Flora, 1963; Floyd, 1999; Fran, 1996; Frances, 2004; Frederic, 1979
- Georges, 1998; Gilbert, 1988; Gloria, 1985; Gracie, 1959
- Hattie, 1961; Hazel, 1954; Hilda, 1964; Hortense, 1996; Hugo, 1989
- Inez, 1966; Ione, 1955; Iris, 2001; Isabel, 2003; Ivan, 2004
- Janet, 1955; Jeanne, 2004; Joan, 1988
- Katrina, 2005; Keith, 2000; Klaus, 1990
- Luis, 1995
- Marilyn, 1995; Mitch, 1998
- Opal, 1995
- Rita, 2005; Roxanne, 1995
- Wilma, 2005
Winds inside the storm change speed very quickly. To measure the strength, the National Hurricane Center averages all the wind speeds measured in one minute.
Why do they stop?
Hurricanes derive their energy from the water vapor that evaporates from warm ocean water. Therefore, when a hurricane moves over cold water or over land where it gets cut off from its energy source, it will die.
Some years there are many hurricanes and some years there are very few. Wind and rain patterns from all over the globe affect the number of hurricanes in a year.
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