HURRICANES, THE MOST DESTRUCTIVE STORMS
by Steven LJ Russo
Below
is an excerpt of a newspaper column that I wrote back in 1996. The
information below is still correct!
Hurricane season runs from June through November, with the main months
being August and September, so here is everything you always wanted to know
about hurricanes, but were afraid to ask.
Hurricanes are the most destructive of all meteorological phenomena.
In the western Pacific, they are called typhoons, and in other regions
they are referred to as cyclones. The
word comes from the West Indian word "huracan", and originally
referred to storms only in the West Indies.
That name is now given to any similar storm where sustained winds reach
74 miles per hour. Up to that
point, it is named differently. As
a swirling storm, it is called a tropical depression, and when winds reach 40
miles per hour, it becomes a tropical storm.
After it becomes a hurricane, we use the Saffir-Simpson scale of
potential damage based on wind speed. Category
1, where damage is minimal, has wind speeds of 74-95 miles per hour, while
category 2, has wind speeds of 96-110 mph.
When the sustained winds reach 111-130 mph, the hurricane is considered
"major", and damage is extensive.
In 1992, Hurricane Andrew became a category 4 hurricane, where wind
speeds were 131-155 miles per hour. The
most devastating storms are category 5, where sustained winds reach more than
155 mph.
Hurricanes originate near the Equator, and travel towards the north, if
they were born north of it. They
are large, intense low pressure systems whose winds swirl counter clockwise in
the northern hemisphere. These
storms, created in the warm waters of the Atlantic or Gulf of Mexico, usually
last about ten days, traveling around 15-20 miles per hour, but within that time
period, their destructive force is unmatched by any other meteorological event.
When fully grown, a hurricane reaches a diameter of at least 50 miles,
and usually around 160 miles. With
an average wind speed of 130 mph, it's destructive area can be as much as 500
miles across. The center, also known as the "eye", is usually
around 15 miles across, and is nearly a dead calm.
When directly under the eye, blue sky, or stars at night can be seen.
Generally speaking, once the storm hits the cooler waters of the North
Atlantic, or the cooler land masses, it begins to die.
The land also creates friction which slows the storm down leading to it's
death.
Although the wind usually gets top billing, it's actually the water that
kills most people. The "Storm
Surge", a quick rise in the tide, can topple sea walls, uproot trees, and
tear down buildings that have survived 150 mph winds.
Keep in mind, that one cubic foot of sea water weighs 64 pounds, and if
the surge occurs at high tide, it can be as much as 20 feet above the normal
tidal levels. And also keep in mind, that
tides are higher during New and Full Moon. The two most
dangerous areas in the U. S. for storm surge, are New Orleans, where water 20
feet deep can enter the city, and Southern Florida, where there is a shallow
slope of the ocean bottom and a large population.
Due to resources like the Weather Channel, CNN, satellites, computers,
and the National Hurricane Center, loss of life due to hurricanes in the U. S.
has decreased. Where more than 8000
people would die in the early 1900's, fewer that 200 people would die today.
The opposite is true for the costs of damage.
Between 1920 and 1995, damage per hurricane has gone from 1.5 billion
dollars to over 20 billion dollars.
Unfortunately, the next twenty years may be ripe for the development of
major hurricanes. No, don't believe the environmentalists; global warming is
not the cause of hurricanes. Actually, many
scientists believe that Global Warming will actually DECREASE severe storms, due
to less variation of temperature, which is the cause of severe
storms. Do believe William Grey from Colorado State
University. He believes that East
coast hurricanes are linked with rainfall in Africa.
During the wetter years in West Africa, 1941 through 1965, 17 major
hurricanes hit the east coast or Florida. During
the dryer years, 1966 through 1990, only two major hurricanes hit the east
coast, and none in Florida. If the
cycle holds out, then 1991 through 2015 should be wetter than normal in West
Africa, and the number of major hurricanes here should increase.
According to Grey, the major hurricanes should return to the places that have been lull for the past 25 years, and when you take into account population and building growth, "There's going to be hell to pay." Hurricane Andrew back in August of 1992, may have been the beginning of this "hell"; only time will tell.