What is a Hurricane?
A hurricane is a tropical cyclone where winds reach speeds
of more then 119 km per hr. In some hurricanes wind speeds
can reach up to and over 289 km per hour. In the Atlantic,
tropical storms are known as hurricanes, a Carib Indian
word for "big wind." In the West Pacific, they are known as
typhoons, a Chinese word meaning "great wind." In
Australia they are called a willy-willy, while in the Indian
Ocean they are simply known as tropical cyclone. Where
cyclone is a Greek word meaning, "coil." Normally
hurricanes have a life span of 1-30 days in length. After the
30-day mark, the extended contact with cold waters and
land surfaces, the hurricanes will slowing die of and become
a tropical storm.
(http://www.todossantos-baja.com/todos-santos/hurricanes/hurricaneadolph-2001.jpg)
Formation of Hurricanes
Tropical depression and tropical storm are the first two
stages that a cyclone will reach while attaining hurricane
force. Hurricanes start to form by gathering tropical storms
together over the sea. Moist air and thermal energy is taken
in by the low-pressure centre from the oceans surface, and
then air is lifted by the process of convection, while high
pressure in the atmosphere pushes it outward. The going
round of the wind currents will spin the clouds into a tight
coil, which will the make the winds stronger, which will
then become gale force, making the depression into a
hurricane. A mature hurricane has a power that will extend
over 500 mi (805 km) in diameter. Low central pressure will
result in the surface air spiralling inward cyclonically
(Counter clockwise in the Northern Hemisphere and
clockwise in the Southern Hemisphere) making circle that
is about 30km in size that will encircle the hurricanes eye.
The rim of the circle is known as the eye wall, where the
spiralling, moist air is then forced up, causing heat to be
released. Then by reaching tens of thousands of feet above
the ground, the air is pushed towards the storms edges,
which then creates the spirals clouds that we see on satellite
images. The eye wall has the heaviest precipitation and the
highest clouds because of upward velocity of air and
subsequent condensation. Also the eye wall has the highest
and maximum wind speed of the hurricane, because of the
push of pressure outward. On the other hand the eye of the
hurricane is completely different, with no wind and little
precipitation and is usually no clouds, leaving the sky blue.
Sinking currents at the hurricane's core lead to warmer
temperatures in the eye of more then 10°F to 15°F (5°C–8°C)
then the air surrounding the eye.
(http://www1.ncdc.noaa.gov/pub/data/images/four-hurricanes-19980926g84kmir.gif)
Movement and Occurrence of Hurricanes
At the early stages of a hurricane, they travel east bound at
about 16 km/hr. As they progress, they will start to turn
towards the poles as they reach the western margins of the
oceans at 20° to 30° lat., but there are more complex tracks
are common. In the northern hemisphere, hurricanes tend
to form over the Atlantic Ocean and as they grow more
mature they will go westward. Mexico also has hurricanes
that form of the west coast that will move north-eastward
up the coast. Only 3.5 hurricanes on average will mature and
reach the east coast of North America. One of the three
hurricanes usually will come from the Caribbean Sea or the
Gulf of Mexico. On the east side of North America hurricanes
usually form from June to November. While Hurricanes in
the Pacific prefer May through to December. In the Southern
Hemisphere the hurricane season is December to April. The
reason the hurricane seasons are when they are, is because
for a hurricane to form they need warm water and during
these months that’s when the water is the warmest. Most
commonly you will see a picture of a hurricane though
satellite pictures, but airplanes are still the best way to
track hurricanes, only by flying directly through the storm
can you tell how quick it’s moving, how large it is and how
strong the winds are.
(http://www.srh.noaa.gov/jax/research/hurricanes/history/1898/Graphs/Grap
h1.GIF)
Damage Caused by Hurricanes
The number one cause of loss of life and damage done to
property is the winds of the hurricane. Another big factor
the flooding caused torrential rains that are caused. To
determine the severity of a hurricane you would use the
Saffir-Simpson scale, which measures the damage that was
done. It measures/classifies hurricanes on a ladder from
category 1 (minimal), through category 2 (moderate),
category 3 (extensive), and category 4 (extreme), to
category 5 (catastrophic). Since the system was introduced,
there have been only two category 5 hurricanes to hit the
states, one in Florida in 1935 killing over 600 people and in
Mississippi in 1969 killing 256 people and damage of 1.4
billons dollars US. There have been less than ten, category 5
hurricanes to hit in the Atlantic Ocean. Even when a
hurricane dies down to a tropical storm, it can still cause
major damage and flooding, as Hurricane Agnes did in 1972.
Many programs have been set up to try and stop a hurricane
in its early stages. Most recently, damage-mitigation steps
have been put forward including better warning systems
involving real-time satellite imagery. Within 24-36 hours a
hurricane warning is issued if there is threat of a hurricane
conditions. When hurricane conditions (winds greater than
74 mph/119 kph or dangerously high water and rough seas)
are expected in 24 hours or less, a hurricane warning is
issued.
(http://www.eaglesnest.net/weather/saffirsimpson.gif)
Hurricane Names
Since there can be more then one hurricane brewing up in
the ocean, they use a name system, so it won’t be so
confusing and you can tell which hurricane they are talking
about. Names are ready to be used and are made up by
official storm trackers all over the world. The names that
are chosen are used in a six-year rotation, unless they are
retired. Hurricanes names that become retired are really big
in size and cause quite a bit of destructive.
Retired Names:
Agnes
Alicia
Allen
Andrew
Anita
Audrey
Betsy
Bob
Camille
Carla
Carmen
Celia
Cesar
Cleo
Connie
David
Diana
Donna
Elena
Fran
George
Gilbert
Gloria
Hortense
(http://www.goes.noaa.gov/EVENTS/EG41.GIF)
(http://envsc.edcc.edu/hurricanes.jpg)
Janet
Joan
Louis
Marilyn
Mitch
Opal
Roxanne
The Six-Year List of Hurricane Names For Atlantic Storms
2001
Allison
Barry
Chantal
Dean
Erin
Felix
Gabrielle
Humberto
Iris
Jerry
Karen
Lorenzo
Michelle
Noel
Olga
Pablo
Rebekah
Sebastien
Tanya
Van
Wendy
2002
Arthur
Bertha
Cristobal
Dolly
Edouard
Fay
Gustav
Hanna
Isidore
Josephine
Kyle
Lili
Marco
Nana
Omar
Paloma
Rene
Sally
Teddy
Vicky
Wilfred
2003
Ana
Bill
Claudette
Danny
Erika
Fabian
Grace
Henri
Isabel
Juan
Kate
Larry
Mindy
Nicholas
Odette
Peter
Rose
Sam
Teresa
Victor
Wanda
2004
Alex
Bonnie
Charley
Danielle
Earl
Frances
Gaston
Hermine
Ivan
Jeanne
Karl
Lisa
Matthew
Nicole
Otto
Paula
Richard
Shary
Tomas
Virginie
Walter
2005
Arlene
Bret
Cindy
Dennis
Emily
Franklin
Gert
Harvey
Irene
Jose
Katrina
Lee
Maria
Nate
Ophelia
Philippe
Rita
Stan
Tammy
Vince
Wilma
2006
Alberto
Beryl
Chris
Debby
Ernesto
Florence
Gordon
Helene
Isaac
Joyce
Keith
Leslie
Michael
Nadine
Oscar
Patty
Rafael
Sandy
Tony
Valerie
William
(http://www.datanation.com/images/dh.gif)
Tropical Cyclones
(hurricanes)
by: Lee Rafuse and Corey Rafuse
(http://www.north-topsail-beach.org/hurrican.htm)
2003-05-04
Global Geography 12
Mr. Wohlmuth
Works Cited:
“All About Hurricanes.” Scholastic. (1 May 2003)
http://teacher.scholastic.com/activities/wwatch/hurricanes/extreme/trivia.htm
“Hurricanes.”
InfoPlease.com (3 May 2003)
http://www.infoplease.com/spot/hurricanes.html
“Natural Disasters, Hurricanes.” Federal Emergency Management Agency
(3 May 2003)
http://www.fema.gov/kids/hurr.htm
“Questions and Answers About Hurricanes.”
Laboratory (1 May 2003)
http://www.nssl.noaa.gov/edu/hurricane
National Severe Storms