Summer is over and fall has arrived- but many people to the south of us are
observing another season- hurricane season. According to the Montshire Museum of
Science, "hurricanes usually occur in the North Atlantic from June to
November, with most of them in September." On average, between six to eight
hurricanes form in the North Atlantic or North Pacific each year (Montshire).
However, as many as 15 have occurred in the Atlantic in a single year.
Hurricanes are powerful, whirling storms that measure several hundred miles in
diameter. The winds near the center of a hurricane blow at speeds of 74 miles
per hour or more (World Book, 400). Many hurricanes leave a trail of widespread
death and destruction. The definition of a hurricane, according to World Book
Encyclopedia, is an area of low pressure that forms over oceans in tropical
regions. Such a storm in the North Pacific Ocean is called a typhoon, and one in
the South Pacific or Indian Ocean is called a cyclone. Most hurricanes originate
within the doldrums, a "narrow equatorial belt characterized by
intermittent calms, light variable breezes, frequent squalls, and lying between
the northeast and southeast trade winds" (Encarta). Hurricanes consist of
high-velocity winds blowing circularly around a low-pressure center, known as
the eye of the storm. The low-pressure center develops when the warm, saturated
air prevalent in the doldrums is under run and forced upward by denser, cooler
air. From the edge of the storm toward its center, the atmospheric pressure
drops sharply and the wind velocity rises. The winds attain maximum force close
to the point of lowest pressure. Encarta Encyclopedia states that
"hurricanes generally move in a path resembling the curve of a
parabola". Also, that in the "Northern Hemisphere the storms usually
travel first in a northwesterly direction and in the higher latitudes turn
toward the northeast". "In the Southern Hemisphere the usual path of
the hurricane is initially to the southwest and subsequently to the
southeast". Hurricanes travel at varying rates. Those areas in which the
hurricane winds blow in the same direction as the general movement of the storm
are subjected to the maximum destructive violence of the hurricane. According to
the research team at Storm Central, hurricanes go through a set of stages from
birth to dissipation. Tropical disturbance is the beginning of a hurricane, and
it has "no strong winds or closed isobars around an area of low pressure
containing cloudiness and some precipitation". As the surface pressure
begins to fall and winds increase to between 20 and 34 knots the tropical
disturbances become tropical depressions. Tropical Depression has "at least
one isobar that accompanies a drop in pressure in the center of the storm".
Surface winds increase to speeds of 35 to 64 knots. The storm becomes more
organized and the appearance begins to resemble a hurricane because of the
intensifying circulation around the center of the storm. This phase is called
the Tropical Storm. A tropical storm is "stronger than a depression as the
central pressure drops, resulting in several closed isobars at the
surface". Some tropical storms only progress this far and "die back
down", several storms start out appearing as if they will be stronger and
progress faster but lose their strength early on. However, if the storm proceeds
it begins to take on the familiar hurricane appearance. This is a
"pronounced rotation which develops around the center core". The eye
develops corresponding to the "lowest atmospheric pressure near the center
of the storm with spiral rain bands rotating around the eye of the storm".
As surface pressures continue to drop, strengthening the pressure gradient of
the storm, the "storm becomes a hurricane when sustained wind speeds exceed
64 knots". When a storm has advanced to the hurricane stage it can then be
rated by the amount of strength that it has. This is done so by using the Saffir-Simpson
scale, also known as the Simpson and Riehl Scale. The scale is a 1-5 rating
based on the hurricane's present intensity. This is used to give an estimate of
the "potential property damage and flooding expected along the coast from a
hurricane landfall"(Hurricane99). Researchers at the Hurricane 99 weather
site also say that, "wind speed is the determining factor in the scale, as
storm surge values are highly dependent on the slope of the continental shelf in
the landfall region". Well, if there is information on a subject then there
must have been some way to find that information out. "Since 1953, U.S.
military aircraft have been flying into hurricanes to measure wind velocities
and directions, the location and size of the eye, the pressures within the
storms, and their thermal structure" (Encarta). A coordinated system of
tracking hurricanes was developed in the mid- 1950s, and periodic improvements
have been made over the years. Radar, sea-based recording devices,
geosynchronous weather satellites, and other devices now supply data to the
National Hurricane Center in Florida, which follows each storm virtually from
the beginning. "Improved systems of prediction and communication have been
able to minimize loss of life in hurricanes, but property damage is still heavy,
especially in coastal regions". According to Encarta Encyclopedia, the
strongest hurricane to hit the Western Hemisphere in the 20th century, Gilbert,
devastated Jamaica and parts of Mexico in 1988 with winds that gusted up to 350
km/h (218 mph). "Destructive hurricanes in recent U.S. history include
Agnes (1972), with $3 billion in damage and 134 deaths, Hugo (1989), with more
than $4 billion in damage and more than 50 deaths, and Andrew (1992), with an
estimated $12 billion in damage, more than 50 dead, and thousands left
homeless" (Encarta). Hurricanes devastate the lives of many people every
year, by destroying their property and homes, taking the lives of friends and
loved ones, etc. Many advancements have been made over the years to forewarn
potential victims of these horrendous storms. Hurricanes are an act of nature
that no one can ever control. As long as there are bodies of water, wind, and
warm air, we will still be searching for the perfect warning system for those on
the coast. We just have to be thankful that technological advancements have
brought us thus far, now we have only the future and further experimentation to
look forward to.

Bibliography
"Why hurricanes form over warm oceans." USA Today Weather http://www.usatoday.com/weather/whur7.htm,
11/4/99. "Montshire Minute: Hurricanes." Montshire Museum of Science
http://www.montshire.net/minute/mm99027.html, 11/6/99. "How are Atlantic
hurricanes ranked?" Hurricanes99 http://www.hurricanes99.com/huricanesSSS.html,
11/10/99. "What are Hurricanes?" Hurricanes99
http://www.hurricanes99.com/FAQ.html, 11/10/99. "Hurricane Stages of
Development." Storm Central. http://www.stormsearch.com/stages, 11/11/99.
"Hurricanes" Microsoft Encarta Encyclopedia 98. Microsoft, 1993-1997.
"Hurricanes" World Book Encyclopedia. World Book-Childcraft
International Inc. Volume 9: 400-403. Works Cited "Why hurricanes form over
warm oceans." USA Today Weather http://www.usatoday.com/weather/whur7.htm,
11/4/99. "Montshire Minute: Hurricanes." Montshire Museum of Science
http://www.montshire.net/minute/mm99027.html, 11/6/99. "How are Atlantic
hurricanes ranked?" Hurricanes99 http://www.hurricanes99.com/huricanesSSS.html,
11/10/99. "What are Hurricanes?" Hurricanes99
http://www.hurricanes99.com/FAQ.html, 11/10/99. "Hurricane Stages of
Development." Storm Central. http://www.stormsearch.com/stages, 11/11/99.
"Hurricanes" Microsoft Encarta Encyclopedia 98. Microsoft, 1993-1997.
"Hurricanes" World Book Encyclopedia. World Book-Childcraft
International Inc. Volume 9: 400-403.