Tropical
Storms - An Introduction
A
Tropical Storms are also known as Hurricanes (Atlantic), Tropical
Cyclones (South East Asia), Willy Willies (Australia) and Typhoons
(Pacific).
What
are Tropical Storms?
Tropical
Storms are areas of extreme low pressure. This means air is rising,
causing 'low pressure' on the earth's surface. The maximum
sustained surface wind speed (using the U.S. 1-minute average)
ranges from 34 knots (39 mph or 63 kph) to 63 knots (73 mph or
118 kph).
How
are Tropical Storms named?
All tropical
stroms are given names so they can be identified and tracked as
they move over oceans. In 1979, both women and men's names were
used. One name for each letter of the alphabet is selected, except
for Q, U and Z. For Atlantic Ocean hurricanes, the names may be
French, Spanish or English, since these are the major languages
bordering the Atlantic Ocean where the storm occur.
The World
Meteorological Organization uses six lists in rotation. If the
tropical storm is particularly deadly or costly the name is retired
and a new one is chosen.
The Six-Year
List of Hurricane Names For Atlantic Storms:
1996
Arthur
Bertha
Cesar
Dolly
Edouard
Fran
Gustav
Hortense
Isidore
Josephine
Kyle
Lili
Marco
Nanav
Omar
Paloma
Rene
Sally
Teddy
Vicky
Wilfred
|
1997
Ana
Bill
Claudette
Danny
Erika
Fabian
Grace
Henri
Isabel
Juan
Kate
Larry
Mindy
Nicholas
Odette
Peter
Rose
Sam
Teresa
Victor
Wanda
|
1998
Alex
Bonnie
Charley
Danielle
Earl
Frances
Georges
Hermine
Ivan
Jeanne
Karl
Lisa
Mitch
Nicole
Otto
Paula
Richard
Shary
Tomas
Virginie
Walter
|
1999
Arlene
Bret
Cindy
Dennis
Emily
Floyd
Gert
Harvey
Irene
Jose
Katrina
Lenny
Maria
Nate
Ophelia
Philippe
Rita
Stan
Tammy
Vince
Wilma
|
2000
Alberto
Beryl
Chris
Debby
Ernesto
Florence
Gordon
Helene
Isaac
Joyce
Keith
Leslie
Michael
Nadine
Oscar
Patty
Rafael
Sandy
Tony
Valerie
William
|
2001
Allison
Barry
Chantal
Dean
Erin
Felix
Gabrielle
Humberto
Iris
Jerry
Karen
Lorenzo
Michelle
Noel
Olga
Pablo
Rebekah
Sebastien
Tanya
Van
Wendy
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You can find
out the names of past, present and future Eastern North Pacific
tropical storms here.
How
do Tropical Storms occur?
Tropical
Storms start within 8º and 15º north and south of the equator
where surface sea temperatures reach 27ºC. The air above the warm
sea is heated and rises. This causes low pressure.
As the air rises it cools then condenses, forming clouds. Air
around the weather system rushes in to fill the gap caused by
the rising air. The air begins to spiral. This is caused by the
spinning movement of the earth.
The weather system generates heat which powers the storm, causing
wind speeds to increase. This causes the Tropical Storm to sustain
itself. Tropical storms rely on plenty of warm, moist air from
the sea - this is why they die out over land.
What
is the structure of a Tropical Storm?
The central part of the tropical
storm is known as the eye. The eye is usually between 30-50km
across. It is an area of calm, with light winds and no rain. It
contains descending air. Large cumulonimbus clouds surround the
eye. These are caused by moist air condensing as it rises. Wind
speeds average 160km per hour around the eye.
How
can we reduce the impact?
Click
here
to find out how to prepare for a tropical storm.
Case
Studies
Below is a
list of Tropical Storms, each with a link to a site containing information
about it:
1. Hurricane
Andrew - 1992 Americas costliest hurricane
2. Hurricane
Mitch - 1998
3. Indian
'Super Cyclone' The strongest and deadliest cyclone in the
region since the Bangladesh cyclone of April 1991
4. Cyclone
Eline - 2000 The cause of the major disaster in Mozambique
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