Tropical cyclones occur
all around the world, but
they are not always
referred to by the same
name. They are called
hurricanes in the Atlantic
and Caribbean, typhoons
in the West Pacific,
baguios in the
Philippines, cordonazos
in Mexico, and tainos in
Haiti.
Tropical cyclones consist of high speed winds blowing
circularly around a low pressure center which averages 24km
in diameter. This center is known as the eye of the storm. The
eye develops when warm, saturated air is forced up by denser,
cooler air. The atmospheric pressure in a tropical cyclone
drops sharply as you get closer to the center. The winds also
stop and the clouds lift, but the seas remain very violent in the
eye.
Evaporation and conduction transfer heat to the
atmosphere quickly when the sun warms up the oceans. The
water vapour generated by this is the fuel that drives the
tropical storm because the vapour condensing into clouds
releases enormous amounts of heat into the cyclone.
This mix of heat and moisture frequently cause several
thunderstorms that can grow into a tropical cyclone. These
thunderstorms require an easterly wave to be developed into
an Atlantic hurricane. Typhoons in the Pacific and Indian
oceans and some hurricanes in the Atlantic are started by the
waves near the equator.
For a storm to develop
and mature into a tropical
cyclone, it must overcome
many obstacles. In fact, only
about nine of the more than
1000 seedlings tracked each
year in the Atlantic will
evolve into tropical cyclones.
That’s less than 1%!
Tropical cyclones are most likely to occur in the hot,
humid, late-summer environment of the tropics and are least
likely to occur at the north and south poles. They occur
several times a year.
There have been no such events in our area because they
require the warm ocean water, in the tropics, to form.
• Arthur
• Bertha
• Cristobal
• Dolly
• Edouard
• Fay
• Gustav
• Hanna
• Isidore
• Josephine
• Kyle
• Lili
• Many people have been working to improve systems of
prediction of hurricanes. They have been using radar, sea-
based recording devices, geosynchronous weather satellites,
and other devices. They have also been following storms
starting from when they are formed. This has helped
minimize loss of life, but property damage is still great.
• The area affected by winds of destructive force can be
larger than 240km in diameter, and areas affected by gale
winds average 480km in diameter.
• Tropical cyclones have killed more people around the
world than any other kind of storm.
• Tropical cyclones are the only types of storms named as
they occur.
• Tropical cyclones can last for as little as a few days to
more than three weeks.
• If the tropical cyclone hits land, it brings a mound of water
that can be up to 6m high, called a storm surge.
• A single tropical cyclone can cause millions of dollars of
damage.