Hurricanes are violent tropical
storms with winds minimum
speed of at least 74 mph. They form
over warm ocean waters, usually
starting as storms. As they drift
slowly and are fueled by the warm
waters of the tropics. Warm, moist
air moves toward the center of the
storm and spirals upward. This
releases torrential rains.
Once the group
of rotating storms churn up enough
water to get wind speeds up to 120
Km per hour, it is called a
hurricane.
As
updrafts suck up more water vapor,
it triggers a cycle of strengthening
that can be stopped only when
contact is made with land or cooler
water.
Inside the Hurricane:
A hurricane is a
powerful storm that measures several hundred
miles in diameter. Hurricanes have two main
parts. The first is the eye of the
hurricane, which is a calm area in the
center of the storm. Usually, the eye of a
hurricane measures about 20 miles in
diameter, and has very few clouds. The
second part is the wall of clouds that
surrounds the calm eye. This is where the
hurricane's strongest winds and heaviest
rain occur.
Difference Between Hurricanes
and tropical Storms:
Tropical storms are storms that have winds between
39 and 73 miles per hour. Hurricanes are more severe
and more dangerous forms of tropical storms. They
have winds of 74 miles per hour or more. These
storms form over oceans and seas, like the Atlantic
Ocean, the Caribbean Sea, the Gulf of Mexico, and
the Pacific Ocean.
Watch Hurricane Video
Hurricane
Scale
Although all hurricanes are dangerous, some
are more so than others. A hurricane's
destructive power is a combination of storm
surge, wind, rain, and other factors.
Hurricanes are categorized are as follows:
CATEGORY 1
Winds are 74 to 95 mph; storm surge is 4 to
5 feet above normal. The hurricane has a
barometric pressure of 28.95 inches with no
real damage to building structures.
CATEGORY 2
Winds are 96 to 110 mph; storm surge is 6 to
8 feet above normal. The pressure is between
28.50 and 28.94 inches. There may be
moderate damage to roofing material, doors,
and windows.
CATEGORY 3
Winds are 111 to 130 mph; storm surge is 9
to 12 feet above normal. The pressure is
between 27.91 and 28.49 inches. Damage can
be extensive with some structural damage to
small buildings. Terrain continuously lower
than 5 feet above sea level may be flooded
inland as far as 6 miles.
CATEGORY 4
Winds are 131 to 155 mph; storm surge is 13
to 18 feet above normal. The pressure is
between 27.17 and 27.90 inches. Some extreme
damage will take place. Major erosion of
beach areas and major damage to lower floors
of structures near the shore will occur.
Massive evacuation of residential areas
inland as far as 6 miles may be required.
CATEGORY 5
Winds are greater than 155 mph; storm surge
is greater than 18 feet above normal. The
pressure is less than 27.17 inches. The
damage can be devastating. Some buildings
may be blown over or away. Major damage to
lower floors of all structures located less
than 15 feet above sea level and within 500
yards of the shoreline is likely. Massive
evacuation may be required of residential
areas on low ground within 5 to 10 miles of
the shoreline.
What to do Before a Hurricane:
Check
here
for more details
How Hurricanes form - Courtesy
NASA watch Video
Are Hurricanes
And Climate Change interlinked?
Studies shows
that the earth's climate is warmed
by increasing levels of greenhouse
gases in the atmosphere. However
researchers cannot say with
certainty at present whether more or
fewer hurricanes will occur in the
future with global warming. However
research indicates that the
hurricanes which will occur near the
end of the 21st century are expected
to be stronger and may have
significantly more intense rainfall
than present day hurricanes. This
expectation (figure below) is based
on an anticipated enhancement of
energy available to the storms due
to higher tropical sea surface
temperatures.
Fig; Courtesy NOAA
The results shown in Figure above
are based on a simulation study
carried out by Thomas R. Knutson and
Robert E. Tuleya at NOAA's
Geophysical Fluid Dynamics
Laboratory.
