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HURRICANE
& TROPICAL STORM
INFO
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TROPICAL
CYCLONE CLASSIFICATIONS
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Tropical Depression
(numbered)
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20
- 34
knots |
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Tropical Storm
(named)
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35
- 64
knots |
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Hurricane (named)
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65
knots
or higher |
Saffir-Simpson Scale
| Category |
Wind
- Knots |
Wind
- MPH |
Pressure
- MB |
| 1 |
65
- 82 |
74
- 95 |
> 980 |
| 2 |
83
- 95 |
96 - 110 |
965 - 979 |
| 3 |
96 - 113 |
111 - 130 |
945 - 964 |
| 4 |
114 - 135 |
131 - 155 |
920 - 944 |
| 5 |
> 135 |
> 155 |
< 920 |
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Intensity
classifications
Three tropical
cyclones at different stages of development. The youngest, though
recently upgraded to a tropical storm, lacks the organization of the
other two.Tropical cyclones are classified into three main groups,
based on intensity: tropical depressions, tropical storms, and a third
group of more intense storms, whose name depends on the region.
A
tropical depression is an organized system of clouds and
thunderstorms with a defined surface circulation and maximum sustained
winds of less than 17 m/s (33 kt, 38 mph, or 62 km/h). It has no eye,
and does not typically have the organization or the spiral shape of
more powerful storms. It is already a low-pressure system, however,
hence the name "depression."
A tropical
storm is an organized system of strong thunderstorms with a
defined surface circulation and maximum sustained winds between 17 and
32 m/s (34–63 kt, 39–73 mph, or 62–117
km/h). At this point, the distinctive cyclonic shape starts to develop,
though an eye is usually not present. Government weather services
assign first names to systems that reach this intensity (thus the term
named storm).
A hurricane or typhoon
(sometimes simply referred to as a tropical cyclone, as opposed to a
depression or storm) is a system with sustained winds greater than 33
m/s (64 kt, 74 mph, or 118 km/h).[1] A tropical cyclone tends to
develop an eye, an area of relative calm (and lowest atmospheric
pressure) at the center of circulation. The eye is often visible in
satellite images as a small, circular, cloud-free spot. Surrounding the
eye is the eyewall, an area about 10–50 mi (16–80
km) wide in which the strongest thunderstorms and winds circulate
around the storm's center.
The circulation of clouds
around a cyclone's center imparts a distinct spiral shape to the
system. Bands or arms may extend over great distances as clouds are
drawn toward the cyclone. The direction of the cyclonic circulation
depends on the hemisphere; it is counterclockwise in the Northern
Hemisphere and clockwise in the Southern Hemisphere. Maximum sustained
winds in the strongest tropical cyclones have been measured at more
than 85 m/s (165 kt, 190 mph, 305 km/h). Intense, mature hurricanes can
sometimes exhibit an inward curving of the eyewall top that resembles a
football stadium: this phenomenon is thus sometimes referred to as the
stadium effect.
Eyewall replacement cycles naturally
occur in intense tropical cyclones. When cyclones reach peak intensity
they usually - but not always - have an eyewall and radius of maximum
winds that contract to a very small size, around 5 to 15 miles. At this
point, some of the outer rain bands may organize into an outer ring of
thunderstorms that slowly moves inward and robs the inner eyewall of
its needed moisture and momentum. During this phase, the tropical
cyclone is weakening (i.e.,... the maximum winds die off a bit and the
central pressure goes up). Eventually the outer eyewall replaces the
inner one completely and the storm can be the same intensity as it was
previously or, in some cases, even stronger. Even if the cyclone is
weaker at the end of the eyewall replacement cycle, the fact that it
has just undergone one and will not undergo another one soon will allow
it to strengthen further, if other conditions allow it to do so. |
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2008 Hurricane
Names
Arthur
Bertha
Cristobal
Dolly
Edouard
Fay
Gustav
Hanna
Ike
Josephine
Kyle
Laura
Marco
Nana
Omar
Paloma
Rene
Sally
Teddy
Vicky
Wilfred
2007
Hurricane
Names
*
Andrea,
*
Barry,
* Chantal,
Dean,
Erin,
Felix,
Gabrielle,
Humberto,
Ingrid,
Jerry,
Karen,
Lorenzo,
Melissa,
Noel,
Olga,
Pablo,
Rebekah,
Sebastien,
Tanya,
Van,
Wendy,
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