Hurricane
Origin of the Hurricane
“HURRICANE derived from
“Hurican”, the Cari god of evil... Alternative spellings: foracan,
foracane, furacana, furacane, furicane, furicano, haracana, harauncana,
haraucane, harrycain, hauracane, haurachana, herican, hericane, hericano,
herocane, herricao, herycano, heuricane, hiracano, hirecano, hurac [s]n,
huracano, hurican, hurleblast, hurlecan, hurlecano, hurlicano, hurricane,
hurricano, hyrracano, urycan, hyrricano, jimmycane, oraucan, uracan,
uracano ”.
Meteorology
The name ‘Hurican’ was derived
from the Maya ‘Hurakan’, one of their creator gods, who blew his breath
across the chaotic water and brought forth dry land.
About Hurricanes
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.
Inside a Hurricane
Hurricanes are
born over warm, tropical oceans.
Hurricanes are fueled by water vapor
that is pushed up from the warm ocean surface, so they can last longer and
sometimes move much further over water than over land. The combination of
heat and moisture, along with the right wind conditions, can create a new
hurricane.
What is a hurricane,
typhoon, or tropical cyclone?
The terms hurricane and typhoon are regionally specific
names for a strong "tropical cyclone". A tropical cyclone is the
generic term for a non-frontal synoptic scale low-pressure system over
tropical or sub-tropical water with organized convection (i.e.
thunderstorm activity) and definite cyclonic surface with circulation.
Hurricanes have winds that
exceed 64 knots (74 mi/hr) and rotate counterclockwise about their centers in
the Northern Hemisphere and clockwise in the Southern. Typhoons, on
the other hand, is a violent, low pressure tropical storm that occurs in
the Western Pacific Ocean. Typhoons are similar to
hurricane. They are given names that are usually associated to people who
have the same personalities with them.
Tropical cyclones with
maximum sustained surface winds (note that
its definition depends upon who is taking the measurements) of less than
17 m/s (34 kt, 39 mph) are called "tropical depressions". (This is not to
be confused with the condition mid-latitude people get during a long,
cold and grey winter wishing they could be closer to the equator.) Once
the tropical cyclone reaches winds of at least 17 m/s, they are typically
called a 'tropical storm" and assigned a name. If winds reach 33 m/s (64
kt, 74 mph), then they are called a hurricane (the North Atlantic
Ocean, the Northeast Pacific Ocean east of the dateline, or the South
Pacific Ocean east of 160E); a typhoon (Northwest Pacific Ocean
west of the dateline); a "sever tropical cyclone" (the Southwest Pacific
Ocean west of 160E or the Southeast Indian Ocean east of 90E); a severe
cyclonic storm" (the North Indian Ocean); and a "tropical cyclone" (the
Southwest Indian Ocean).
The World Meteorology organization
guidelines suggest utilizing a 10 min. average to get a sustained
measurement. Most countries utilize this as the standard. However the
National Hurricane Center (MHZ) and the Joint Typhoon Warning Center
(JTWC) of the USA use a 1 min. averaging periods to get sustained winds.
This difference may provide complications in comparing the statistics from
one basin to another as using a smaller averaging period may slightly
raise the number of occurrences.
What is a major hurricane? What is an intense hurricane?
“Major Hurricane” is term utilized by
the National Hurricane Center for
hurricanes that reach maximum sustained one minute surface winds of at
least 50 m/s (96 kt, 111 mph). This is the equivalent of
category 3,4, and 5 on the Saffir-Simpson scale.
The term “Intense
Hurricane” is unofficial, but is often used in the scientific literature.
It is the same as “Major Hurricane”.
How Hurricanes Move
In the Northern Hemisphere, hurricane winds blow
around the eye in a counterclockwise direction. They blow clockwise in the
Southern Hemisphere. Hurricane eyes travel at speeds of 10 to 15 miles (16
to 24 kilometers) per hour. Most hurricanes move westward at first and
become larger and stronger as they travel. Then they turn from the equator
and pick up speed. Most hurricanes turn east after they reach temperate
latitudes, where they are called extra-tropical storms. Many end as weak
storm centers over cool oceans.
Formation of Hurricanes
A cyclone that
eventually reaches hurricane intensity first passes through two
intermediate stages known as tropical depression and tropical storm.
Hurricanes start over the oceans as a collection of storms in the tropics.
The deepening low-pressure center takes in moist air and thermal energy
from the ocean surface, convection lifts the air, and high pressure higher
in the atmosphere pushes it outward. Rotation of the wind currents tends
to spin the clouds into a tight curl; as the winds reach gale force, the
depression becomes a tropical storm. The mature hurricane is nearly
circularly symmetrical, and its influence often extends over an area 500
mi (805 km) in diameter.
As a result of the extremely low central pressure
(often around 28.35 in./72 cm but sometimes considerably lower, with a
record 25.91 in./65.8 cm registered in a 1958 typhoon) surface air spirals
inward cyclonically (counterclockwise in the Northern Hemisphere and
clockwise in the Southern Hemisphere), converging on a circle of about 20
mi (30 km) diameter that surrounds the hurricane's “eye.” The
circumference of this circle defines the so-called eye wall, where the
inward-spiraling, moisture-laden air is forced aloft, causing condensation
and the concomitant release of latent heat; after reaching altitudes of
tens of thousands of feet above the surface, this air is finally expelled
toward the storm's periphery and eventually creates the spiral bands of
clouds easily identifiable in satellite photographs.
The upward velocity of the air and subsequent
condensation make the eye wall the region of heaviest precipitation and
highest clouds. Because the outward increase in pressure is greatest
there, the eye wall is also the region of maximum wind speed. By contrast,
the hurricane eye is almost calm, experiences little or no precipitation,
and is often exposed to blue sky. Temperatures in the eye are 10°F to 15°F
(5°C–8°C) warmer than those of the surrounding air as a result of sinking
currents at the hurricane's core.
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