Tropical cyclone

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Hurricane Isabel (2003) as seen from orbit during Expedition 7 of the International Space Station. The eye, eyewall, and surrounding rainbands, characteristics of tropical cyclones, are clearly visible in this view from space.

A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain. Depending on its location and strength, a tropical cyclone is referred to by names such as hurricane (/ˈhʌrɨkən/ or /ˈhʌrɨkn/[1][2][3]), typhoon /tˈfn/, tropical storm, cyclonic storm, tropical depression, and simply cyclone.[4]

Tropical cyclones typically form over large bodies of relatively warm water. They derive their energy through the evaporation of water from the ocean surface, which ultimately recondenses into clouds and rain when moist air rises and cools to saturation. This energy source differs from that of mid-latitude cyclonic storms, such as nor'easters and European windstorms, which are fueled primarily by horizontal temperature contrasts. The strong rotating winds of a tropical cyclone are a result of the conservation of angular momentum imparted by the Earth's rotation as air flows inwards toward the axis of rotation. As a result, they rarely form within 5° of the equator.[5] Tropical cyclones are typically between 100 and 4,000 km (62 and 2,485 mi) in diameter.

Tropical refers to the geographical origin of these systems, which form almost exclusively over tropical seas. Cyclone refers to their cyclonic nature, with wind blowing counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. The opposite direction of circulation is due to the Coriolis effect.

In addition to strong winds and rain, tropical cyclones are capable of generating high waves, damaging storm surge, and tornadoes. They typically weaken rapidly over land where they are cut off from their primary energy source. For this reason, coastal regions are particularly vulnerable to damage from a tropical cyclone as compared to inland regions. Heavy rains, however, can cause significant flooding inland, and storm surges can produce extensive coastal flooding up to 40 kilometres (25 mi) from the coastline. Though their effects on human populations are often devastating, tropical cyclones can relieve drought conditions. They also carry heat energy away from the tropics and transport it toward temperate latitudes, which may play an important role in modulating regional and global climate.

Physical structure[edit]

See also: Eye (cyclone)
Typhoon Nabi as seen from the International Space Station, on September 3, 2005.

Tropical cyclones are areas of relatively low pressure in the troposphere, with the largest pressure perturbations occurring at low altitudes near the surface. On Earth, the pressures recorded at the centres of tropical cyclones are among the lowest ever observed at sea level.[6] The environment near the center of tropical cyclones is warmer than the surroundings at all altitudes, thus they are characterized as "warm core" systems.[7]

Wind field[edit]

The near-surface wind field of a tropical cyclone is characterised by air rotating rapidly around a centre of circulation while also flowing radially inwards. At the outer edge of the storm, air may be nearly calm; however, due to the Earth's rotation, the air has non-zero absolute angular momentum. As air flows radially inward, it begins to rotate cyclonically (counter-clockwise in the Northern Hemisphere, and clockwise in the Southern Hemisphere) in order to conserve angular momentum. At an inner radius, air begins to ascend to the top of the troposphere. This radius is typically coincident with the inner radius of the eyewall, and has the strongest near-surface winds of the storm; consequently, it is known as the radius of maximum winds.[8] Once aloft, air flows away from the storm's center, producing a shield of cirrus clouds.[9]

The previously mentioned processes result in a wind field that is nearly axisymmetric: Wind speeds are low at the centre, increase rapidly moving outwards to the radius of maximum winds, and then decay more gradually with radius to large radii. However, the wind field often exhibits additional spatial and temporal variability due to the effects of localized processes, such as thunderstorm activity and horizontal flow instabilities. In the vertical direction, winds are strongest near the surface and decay with height within the troposphere.[10]

Eye and center[edit]

Diagram of a Northern hemisphere hurricane.

At the center of a mature tropical cyclone, air sinks rather than rises. For a sufficiently strong storm, air may sink over a layer deep enough to suppress cloud formation, thereby creating a clear "eye". Weather in the eye is normally calm and free of clouds, although the sea may be extremely violent.[11] The eye is normally circular in shape, and is typically 30–65 km (19–40 mi) in diameter, though eyes as small as 3 km (1.9 mi) and as large as 370 km (230 mi) have been observed.[12][13]

The cloudy outer edge of the eye is called the "eyewall". The eyewall typically expands outward with height, resembling an arena football stadium; this phenomenon is sometimes referred to as the stadium effect.[14] The eyewall is where the greatest wind speeds are found, air rises most rapidly, clouds reach to their highest altitude, and precipitation is the heaviest. The heaviest wind damage occurs where a tropical cyclone's eyewall passes over land.[11]

In a weaker storm, the eye may be obscured by the central dense overcast, which is the upper-level cirrus shield that is associated with a concentrated area of strong thunderstorm activity near the center of a tropical cyclone.[15]

The eyewall may vary over time in the form of eyewall replacement cycles, particularly in intense tropical cyclones. Outer rainbands can organize into an outer ring of thunderstorms that slowly moves inward, which is believed to rob the primary eyewall of moisture and angular momentum. When the primary eyewall weakens, the tropical cyclone weakens temporarily. The outer eyewall eventually replaces the primary one at the end of the cycle, at which time the storm may return to its original intensity.[16]

Intensity[edit]

Storm "intensity" is defined as the maximum wind speed in the storm. This speed is taken as either a 1-minute or a 10-minute average at the standard reference height of 10 meters. The choice of averaging period, as well as the naming convention for classifying storms, differs across forecast centers and ocean basins.

Size[edit]

Size descriptions of tropical cyclones
ROCI Type
Less than 2 degrees latitude Very small/midget
2 to 3 degrees of latitude Small
3 to 6 degrees of latitude Medium/Average
6 to 8 degrees of latitude Large
Over 8 degrees of latitude Very large[17]

There are a variety of metrics commonly used to measure storm size. The most common metrics include the radius of maximum wind, the radius of 34-knot wind (i.e. gale force), the radius of outermost closed isobar (ROCI), and the radius of vanishing wind.[18][19] An additional metric is the radius at which the cyclone's relative vorticity field decreases to 1×10−5 s−1.[20]

On Earth, tropical cyclones span a large range of sizes, from 100–2000 km as measured by the radius of vanishing wind. They are largest on average in the northwest Pacific Ocean basin and smallest in the eastern Pacific Ocean basin. If the radius of outermost closed isobar is less than two degrees of latitude (222 km (138 mi)), then the cyclone is "very small" or a "midget". A radius of 3–6 latitude degrees (333–670 km (207–416 mi)) is considered "average sized". "Very large" tropical cyclones have a radius of greater than 8 degrees (888 km (552 mi)).[17] Observations indicate that size is only weakly correlated to variables such as storm intensity (i.e. maximum wind speed), radius of maximum wind, latitude, and maximum potential intensity.[19][21]

Size plays an important role in modulating damage caused by a storm. All else equal, a larger storm will impact a larger area for a longer period of time. Additionally, a larger near-surface wind field can generate higher storm surge due to the combination of longer wind fetch, longer duration, and enhanced wave setup.[22] For example, Hurricane Sandy, which struck the eastern U.S. in 2012, barely attained hurricane intensity prior to landfall yet was one of the costliest landfalling hurricanes in U.S. history because of its extremely large size.

The upper circulation of strong hurricanes extends into the tropopause of the atmosphere, which at low latitudes is 15,000–18,000 metres (50,000–60,000 ft).[23]

Physics and energetics[edit]

Tropical cyclones exhibit an overturning circulation where air inflows at low levels near the surface, rises in thunderstorm clouds, and outflows at high levels near the tropopause.[24]

The three-dimensional wind field in a tropical cyclone can be separated into two components: a "primary circulation" and a "secondary circulation". The primary circulation is the rotational part of the flow; it is purely circular. The secondary circulation is the overturning (in-up-out-down) part of the flow; it is in the radial and vertical directions. The primary circulation has the strongest winds and is responsible for the majority of the damage a storm causes, while the secondary circulation is slower but governs the energetics of the storm.

Secondary circulation: a Carnot heat engine[edit]

A tropical cyclone's primary energy source is the evaporation of water from the ocean surface, which ultimately recondenses into clouds and rain when moist air rises and cools to saturation. The energetics of the system may be idealized as an atmospheric Carnot heat engine.[25] First, inflowing air near the surface acquires heat primarily via evaporation of water (i.e. latent heat) at the temperature of the warm ocean surface. Second, air rises and cools within the eyewall while conserving total heat content (latent heat is simply converted to sensible heat during condensation). Third, air outflows and loses heat via infrared radiation to space at the temperature of the cold tropopause. Finally, air subsides and warms at the outer edge of the storm while conserving total heat content. The first and third legs are nearly isothermal, while the second and fourth legs are nearly isentropic. This in-up-out-down overturning flow is known as the secondary circulation. The Carnot perspective provides an upper bound on the maximum wind speed that a storm can attain.

Scientists estimate that a tropical cyclone releases heat energy at the rate of 50 to 200 exajoules (1018 J) per day,[26] equivalent to about 1 PW (1015 watt). This rate of energy release is equivalent to 70 times the world energy consumption of humans and 200 times the worldwide electrical generating capacity, or to exploding a 10-megaton nuclear bomb every 20 minutes.[26][27]

Primary circulation: rotating winds[edit]

The primary rotating flow in a tropical cyclone results from the conservation of angular momentum by the secondary circulation. Absolute angular momentum on a rotating planet M is given by

M = \frac{1}{2}fr^2 + vr

where f is the Coriolis parameter, v is the azimuthal (i.e. rotating) wind speed, and r is the radius to the axis of rotation. The first term on the right hand side is the component of planetary angular momentum that projects onto the local vertical (i.e. the axis of rotation). The second term on the right hand side is the relative angular momentum of the circulation itself with respect to the axis of rotation. Because the planetary angular momentum term vanishes at the equator (where f=0 ), tropical cyclones rarely form within 5° of the equator.[5][28]

As air flows radially inward at low levels, it begins to rotate cyclonically in order to conserve angular momentum. Similarly, as rapidly rotating air flows radially outward near the tropopause, its cyclonic rotation decreases and ultimately changes sign at large enough radius, resulting in an upper-level anti-cyclone. The result is a vertical structure characterized by a strong cyclone at low levels and a strong anti-cyclone near the tropopause; from thermal wind balance, this corresponds to a system that is warmer at its center than in the surrounding environment at all altitudes (i.e. "warm-core"). From hydrostatic balance, the warm core translates to lower pressure at the center at all altitudes, with the maximum pressure drop located at the surface.[10]

Maximum potential intensity[edit]

Due to surface friction, the inflow only partially conserves angular momentum. Thus, the sea surface lower boundary acts as both a source (evaporation) and sink (friction) of energy for the system. This fact leads to the existence of a theoretical upper bound on the strongest wind speed that a tropical cyclone can attain. Because evaporation increases linearly with wind speed (just as climbing out of a pool feels much colder on a windy day), there is a positive feedback on energy input into the system known as the Wind-Induced Surface Heat Exchange (WISHE) feedback.[25] This feedback is offset when frictional dissipation, which increases with the cube of the wind speed, becomes sufficiently large. This upper bound is called the "maximum potential intensity", v_p, and is given by

v_p^2 = \frac{C_k}{C_d}\frac{T_s - T_o}{T_o}\Delta k

where T_s is the temperature of the sea surface, T_o is the temperature of the outflow ([K]), \Delta k is the enthalpy difference between the surface and the overlying air ([J/kg]), and C_k and C_d are the surface exchange coefficients ([dimensionless]) of enthalpy and momentum, respectively.[29] The surface-air enthalpy difference is taken as \Delta k = k^*_s-k, where k^*_s is the saturation enthalpy of air at sea surface temperature and sea-level pressure and k is the enthalpy of boundary layer air overlying the surface.

The maximum potential intensity is predominantly a function of the background environment alone (i.e. without a tropical cyclone), and thus this quantity can be used to determine which regions on Earth can support tropical cyclones of a given intensity, and how these regions may evolve in time.[30][31] Specifically, the maximum potential intensity has three components, but its variability in space and time is due predominantly to the variability in the surface-air enthalpy difference component \Delta k.

Derivation[edit]

A tropical cyclone may be viewed as a heat engine that converts input heat energy from the surface into mechanical energy that can be used to do mechanical work against surface friction. At equilibrium, the rate of net energy production in the system must equal the rate of energy loss due to frictional dissipation at the surface, i.e.

W_{in} = W_{out}

The rate of energy loss per unit surface area from surface friction, W_{out}, is given by

W_{out} = C_d \rho |\mathbf{u}|^3

where \rho is the density of near-surface air ([kg/m3]) and |\mathbf{u}| is the near surface wind speed ([m/s]).

The rate of energy production per unit surface area, W_{in} is given by

W_{in} = \epsilon Q_{in}

where \epsilon is the heat engine efficiency and Q_{in} is the total rate of heat input into the system per unit surface area. Given that a tropical cyclone may be idealized as a Carnot heat engine, the Carnot heat engine efficiency is given by

\epsilon = \frac{T_s-T_o}{T_s}

Heat (enthalpy) per unit mass is given by

k = C_pT + L_vq

where C_p is the heat capacity of air, T is air temperature, L_v is the latent heat of vaporization, and q is the concentration of water vapor. The first component corresponds to sensible heat and the second to latent heat.

There are two sources of heat input. The dominant source is the input of heat at the surface, primarily due to evaporation. The bulk aerodynamic formula for the rate of heat input per unit area at the surface, Q_{in:k}, is given by

Q_{in:k} = C_k \rho |\mathbf{u}|\Delta k

where \Delta k = k^*_s-k represents the enthalpy difference between the ocean surface and the overlying air. The second source is the internal sensible heat generated from frictional dissipation (equal to W_{out}), which occurs near the surface within the tropical cyclone and is recycled to the system.

Q_{in:friction} = C_d \rho |\mathbf{u}|^3

Thus, the total rate of net energy production per unit surface area is given by

W_{in} = \frac{T_s-T_o}{T_s}\left(C_k \rho |\mathbf{u}|\Delta k + C_d \rho |\mathbf{u}|^3\right)

Setting W_{in} = W_{out} and taking |\mathbf{u}| \approx v (i.e. the rotational wind speed is dominant) leads to the solution for v_p given above. This derivation assumes that total energy input and loss within the system can be approximated by their values at the radius of maximum wind. The inclusion of Q_{in:friction} acts to multiply the total heat input rate by the factor \frac{T_s}{T_o}. Mathematically, this has the effect of replacing T_s with T_o in the denominator of the Carnot efficiency.

An alternative definition for the maximum potential intensity, which is mathematically equivalent to the above formulation, is

v_p = \sqrt{\frac{T_s}{T_o}\frac{C_k}{C_d}(CAPE^*_s-CAPE_b)|_m}

where CAPE stands for the Convective Available Potential Energy, CAPE^*_s is the CAPE of an air parcel lifted from saturation at sea level in reference to the environmental sounding, CAPE_b is the CAPE of the boundary layer air, and both quantities are calculated at the radius of maximum wind.[32]

Characteristic values and variability on Earth[edit]

On Earth, a characteristic temperature for T_s is 300 K and for T_o is 200 K, corresponding to a Carnot efficiency of \epsilon = 1/3. The ratio of the surface exchange coefficients, C_k/C_d, is typically taken to be 1. However, observations suggest that the drag coefficient C_d varies with wind speed and may decrease at high wind speeds within the boundary layer of a mature hurricane.[33] Additionally, C_k may vary at high wind speeds due to the effect of sea spray on evaporation within the boundary layer.[34]

A characteristic value of the maximum potential intensity, v_p, is 80 m/s. However, this quantity varies significantly across space and time, particularly within the seasonal cycle, spanning a range of 0–100 m/s.[32] This variability is primarily due to variabliity in the surface enthalpy disequilibrium ( \Delta k ) as well as in the thermodynamic structure of the troposphere, which are controlled by the large-scale dynamics of the tropical climate. These processes are modulated by factors including the sea surface temperature (and underlying ocean dynamics), background near-surface wind speed, and the vertical structure of atmospheric radiative heating.[35] The nature of this modulation is complex, particularly on climate time-scales (decades or longer). On shorter time-scales, variability in the maximum potential intensity is commonly linked to sea surface temperature perturbations from the tropical mean, as regions with relatively warm water have thermodynamic states much more capable of sustaining a tropical cyclone than regions with relatively cold water.[36] However, this relationship is indirect via the large-scale dynamics of the tropics; the direct influence of the absolute sea surface temperature on v_p is weak in comparison.

Interaction with the upper ocean[edit]

Chart displaying the drop in surface temperature in the Gulf of Mexico as Hurricanes Katrina and Rita passed over

The passage of a tropical cyclone over the ocean causes the upper layers of the ocean to cool substantially, which can influence subsequent cyclone development. This cooling is primarily caused by wind-driven mixing of cold water from deeper in the ocean with the warm surface waters. This effect results in a negative feedback process that can inhibit further development or lead to weakening. Additional cooling may come in the form of cold water from falling raindrops (this is because the atmosphere is cooler at higher altitudes). Cloud cover may also play a role in cooling the ocean, by shielding the ocean surface from direct sunlight before and slightly after the storm passage. All these effects can combine to produce a dramatic drop in sea surface temperature over a large area in just a few days.[37]

Major basins and related warning centers[edit]

Basins and WMO Monitoring Institutions[38]
Basin Responsible RSMCs and TCWCs
North Atlantic National Hurricane Center (United States)
North-East Pacific National Hurricane Center (United States)
North-Central Pacific Central Pacific Hurricane Center (United States)
North-West Pacific Japan Meteorological Agency
North Indian Ocean India Meteorological Department
South-West Indian Ocean Météo-France
Australian region Bureau of Meteorology (Australia)
Indonesian Meteorological and Geophysical Agency
Papua New Guinea National Weather Service
Southern Pacific Fiji Meteorological Service
Meteorological Service of New Zealand
: Indicates a Tropical Cyclone Warning Center

There are six Regional Specialized Meteorological Centers (RSMCs) worldwide. These organizations are designated by the World Meteorological Organization and are responsible for tracking and issuing bulletins, warnings, and advisories about tropical cyclones in their designated areas of responsibility. In addition, there are six Tropical Cyclone Warning Centers (TCWCs) that provide information to smaller regions.[39] The RSMCs and TCWCs are not the only organizations that provide information about tropical cyclones to the public. The Joint Typhoon Warning Center (JTWC) issues advisories in all basins except the Northern Atlantic for the purposes of the United States Government.[40] The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) issues advisories and names for tropical cyclones that approach the Philippines in the Northwestern Pacific to protect the life and property of its citizens.[41] The Canadian Hurricane Center (CHC) issues advisories on hurricanes and their remnants for Canadian citizens when they affect Canada.[42]

On March 26, 2004, Cyclone Catarina became the first recorded South Atlantic cyclone and subsequently struck southern Brazil with winds equivalent to Category 2 on the Saffir-Simpson Hurricane Scale. As the cyclone formed outside the authority of another warning center, Brazilian meteorologists initially treated the system as an extratropical cyclone, but later on classified it as tropical.[43]

Formation[edit]

Main article: Tropical cyclogenesis
Map of the cumulative tracks of all tropical cyclones during the 1985–2005 time period. The Pacific Ocean west of the International Date Line sees more tropical cyclones than any other basin, while there is almost no activity in the Atlantic Ocean south of the Equator.
Map of all tropical cyclone tracks from 1945 to 2006. Equal-area projection.

Worldwide, tropical cyclone activity peaks in late summer, when the difference between temperatures aloft and sea surface temperatures is the greatest. However, each particular basin has its own seasonal patterns. On a worldwide scale, May is the least active month, while September is the most active month. November is the only month in which all the tropical cyclone basins are active.[44]

Times[edit]

In the Northern Atlantic Ocean, a distinct cyclone season occurs from June 1 to November 30, sharply peaking from late August through September.[44] The statistical peak of the Atlantic hurricane season is September 10. The Northeast Pacific Ocean has a broader period of activity, but in a similar time frame to the Atlantic.[45] The Northwest Pacific sees tropical cyclones year-round, with a minimum in February and March and a peak in early September. In the North Indian basin, storms are most common from April to December, with peaks in May and November.[44] In the Southern Hemisphere, the tropical cyclone year begins on July 1 and runs all year-round encompassing the tropical cyclone seasons, which run from November 1 until the end of April, with peaks in mid-February to early March.[44][46]

Season lengths and averages
Basin Season
start
Season
end
Tropical
Storms
Hurricanes Refs
North Atlantic June 1 November 30 12.1 6.4 [47]
Eastern Pacific May 15 November 30 16.6 8.9 [47]
Western Pacific January 1 December 31 27.0 17.0 [47]
North Indian January 1 December 31 4.8 1.5 [47]
South-West Indian July 1 June 30 9.3 5.0 [47][48]
Australian region November 1 April 30 11.0 [49]
Southern Pacific November 1 April 30 7.4 4 [50]
Global January 1 December 31 86.0 46.9 [47]


Factors[edit]

Waves in the trade winds in the Atlantic Ocean—areas of converging winds that move along the same track as the prevailing wind—create instabilities in the atmosphere that may lead to the formation of hurricanes.

The formation of tropical cyclones is the topic of extensive ongoing research and is still not fully understood.[51] While six factors appear to be generally necessary, tropical cyclones may occasionally form without meeting all of the following conditions. In most situations, water temperatures of at least 26.5 °C (79.7 °F) are needed down to a depth of at least 50 m (160 ft);[52] waters of this temperature cause the overlying atmosphere to be unstable enough to sustain convection and thunderstorms.[53] Another factor is rapid cooling with height, which allows the release of the heat of condensation that powers a tropical cyclone.[52] High humidity is needed, especially in the lower-to-mid troposphere; when there is a great deal of moisture in the atmosphere, conditions are more favorable for disturbances to develop.[52] Low amounts of wind shear are needed, as high shear is disruptive to the storm's circulation.[52] Tropical cyclones generally need to form more than 555 km (345 mi) or five degrees of latitude away from the equator, allowing the Coriolis effect to deflect winds blowing towards the low pressure center and creating a circulation.[52] Lastly, a formative tropical cyclone needs a pre-existing system of disturbed weather. Tropical cyclones will not form spontaneously.[52] Low-latitude and low-level westerly wind bursts associated with the Madden-Julian oscillation can create favorable conditions for tropical cyclogenesis by initiating tropical disturbances.[54]

Locations[edit]

Most tropical cyclones form in a worldwide band of thunderstorm activity near the equator, referred to as the Intertropical Front (ITF), the Intertropical Convergence Zone (ITCZ), or the monsoon trough.[55][56][57] Another important source of atmospheric instability is found in tropical waves, which contribute to the development of about 85% of intense tropical cyclones in the Atlantic ocean and become most of the tropical cyclones in the Eastern Pacific.[58][59][60] The majority forms between 10 and 30 degrees of latitude away of the equator,[61] and 87% forms no farther away than 20 degrees north or south.[62][63] Because the Coriolis effect initiates and maintains their rotation, tropical cyclones rarely form or move within 5 degrees of the equator, where the effect is weakest.[62] However, it is still possible for tropical systems to form within this boundary as Tropical Storm Vamei and Cyclone Agni did in 2001 and 2004, respectively.[64][65]

Movement[edit]

The movement of a tropical cyclone (i.e. its "track") is typically approximated as the sum of two terms: "steering" by the background environmental wind and "beta drift".[66]

Environmental steering[edit]

Environmental steering is the dominant term. Conceptually, it represents the movement of the storm with the background environment, akin to "leaves carried along by a stream".[67] Physically, the flow field in the vicinity of a tropical cyclone may be decomposed into two parts: the flow associated with the storm itself, and the large-scale background flow of the environment in which the storm is embedded. In this way, tropical cyclone motion may be represented to first-order simply as the advection of the storm by the local environmental flow. This environmental flow is termed the "steering flow".

Climatologically, tropical cyclones are steered primarily westward by the east-to-west trade winds on the equatorward side of the subtropical ridge—a persistent high-pressure area over the world's subtropical oceans.[67] In the tropical North Atlantic and Northeast Pacific oceans, the trade winds steer tropical easterly waves westward from the African coast toward the Caribbean Sea, North America, and ultimately into the central Pacific ocean before the waves dampen out.[59] These waves are the precursors to many tropical cyclones within this region.[58] In contrast, in the Indian Ocean and Western Pacific in both hemispheres, tropical cyclogenesis is influenced less by tropical easterly waves and more by the seasonal movement of the Intertropical Convergence Zone and the monsoon trough.[68] Additionally, tropical cyclone motion can be influenced by transient weather systems, such as extratropical cyclones.

Beta drift[edit]

In addition to environmental steering, a tropical cyclone will tend to drift slowly poleward and westward, a motion known as "beta drift". This motion is due to the superposition of a vortex, such as a tropical cyclone, onto an environment in which the Coriolis force varies with latitude, such as on a sphere or beta plane. It is induced indirectly by the storm itself, the result of a feedback between the cyclonic flow of the storm and its environment.

Physically, the cyclonic circulation of the storm advects environmental air poleward east of center and equatorward west of center. Because air must conserve its angular momentum, this flow configuration induces a cyclonic gyre equatorward and westward of the storm center and an anticyclonic gyre poleward and eastward of the storm center. The combined flow of these gyres acts to advect the storm slowly poleward and westward. This effect occurs even if there is zero environmental flow.

Multiple storm interaction[edit]

Main article: Fujiwhara effect

A third component of motion that occurs relatively infrequently involves the interaction of multiple tropical cyclones. When two cyclones approach one another, their centers will begin orbiting cyclonically about a point between the two systems. Depending on their separation distance and strength, the two vortices may simply orbit around one another or else may spiral into the center point and merge. When the two vortices are of unequal size, the larger vortex will tend to dominate the interaction, and the smaller vortex will orbit around it. This phenomenon is called the Fujiwhara effect, after Sakuhei Fujiwhara.[69]

Interaction with the mid-latitude westerlies[edit]

See also: Westerlies
Storm track of Typhoon Ioke, showing recurvature off the Japanese coast in 2006

Though a tropical cyclone typically moves from east to west in the tropics, its track may shift poleward and eastward either as it moves west of the subtropical ridge axis or else if it interacts with the mid-latitude flow, such as the jet stream or an extratropical cyclone. This motion, termed "recurvature", commonly occurs near the western edge of the major ocean basins, where the jet stream typically has a poleward component and extratropical cyclones are common.[70] An example of tropical cyclone recurvature was Typhoon Ioke in 2006.[71]

Landfall[edit]

Officially, landfall is when a storm's center (the center of its circulation, not its edge) crosses the coastline.[8] Storm conditions may be experienced on the coast and inland hours before landfall; in fact, a tropical cyclone can launch its strongest winds over land, yet not make landfall; if this occurs, then it is said that the storm made a direct hit on the coast.[8] As a result of the narrowness of this definition, the landfall area experiences half of a land-bound storm by the time the actual landfall occurs. For emergency preparedness, actions should be timed from when a certain wind speed or intensity of rainfall will reach land, not from when landfall will occur.[8]

Dissipation[edit]

Factors[edit]

Tropical Storm Franklin, an example of a strongly sheared tropical cyclone in the North Atlantic hurricane basin during 2005

A tropical cyclone can cease to have tropical characteristics in several different ways. One such way is if it moves over land, thus depriving it of the warm water it needs to power itself, quickly losing strength.[72] Most strong storms lose their strength very rapidly after landfall and become disorganized areas of low pressure within a day or two, or evolve into extratropical cyclones. There is a chance a tropical cyclone could regenerate if it managed to get back over open warm water, such as with Hurricane Ivan. If it remains over mountains for even a short time, weakening will accelerate.[73] Many storm fatalities occur in mountainous terrain, when diminishing cyclones unleash their moisture as torrential rainfall.[74] This may lead to deadly floods and mudslides, as was the case with Hurricane Mitch in 1998.[75] Without warm surface water, the storm cannot survive.[76]

A tropical cyclone can dissipate when it moves over waters significantly below 26.5 °C (79.7 °F). This will cause the storm to lose its tropical characteristics, such as a warm core with thunderstorms near the center, and become a remnant low-pressure area. These remnant systems may persist for up to several days before losing their identity. This dissipation mechanism is most common in the eastern North Pacific.[77] Weakening or dissipation can occur if it experiences vertical wind shear, causing the convection and heat engine to move away from the center; this normally ceases development of a tropical cyclone.[78] In addition, its interaction with the main belt of the Westerlies, by means of merging with a nearby frontal zone, can cause tropical cyclones to evolve into extratropical cyclones. This transition can take 1–3 days.[79] Even after a tropical cyclone is said to be extratropical or dissipated, it can still have tropical storm force (or occasionally hurricane/typhoon force) winds and drop several inches of rainfall. In the Pacific Ocean and Atlantic Ocean, such tropical-derived cyclones of higher latitudes can be violent and may occasionally remain at hurricane or typhoon-force wind speeds when they reach the west coast of North America. These phenomena can also affect Europe, where they are known as European windstorms; Hurricane Iris's extratropical remnants are an example of such a windstorm from 1995.[80] A cyclone can also merge with another area of low pressure, becoming a larger area of low pressure. This can strengthen the resultant system, although it may no longer be a tropical cyclone.[78] Studies in the 2000s have given rise to the hypothesis that large amounts of dust reduce the strength of tropical cyclones.[81]

Artificial dissipation[edit]

In the 1960s and 1970s, the United States government attempted to weaken hurricanes through Project Stormfury by seeding selected storms with silver iodide. It was thought that the seeding would cause supercooled water in the outer rainbands to freeze, causing the inner eyewall to collapse and thus reducing the winds.[82] The winds of Hurricane Debbie—a hurricane seeded in Project Stormfury—dropped as much as 31%, but Debbie regained its strength after each of two seeding forays.[83] In an earlier episode in 1947, disaster struck when a hurricane east of Jacksonville, Florida promptly changed its course after being seeded, and smashed into Savannah, Georgia.[84] Because there was so much uncertainty about the behavior of these storms, the federal government would not approve seeding operations unless the hurricane had a less than 10% chance of making landfall within 48 hours, greatly reducing the number of possible test storms. The project was dropped after it was discovered that eyewall replacement cycles occur naturally in strong hurricanes, casting doubt on the result of the earlier attempts. Today, it is known that silver iodide seeding is not likely to have an effect because the amount of supercooled water in the rainbands of a tropical cyclone is too low.[85]

Other approaches have been suggested over time, including cooling the water under a tropical cyclone by towing icebergs into the tropical oceans.[86] Other ideas range from covering the ocean in a substance that inhibits evaporation,[87] dropping large quantities of ice into the eye at very early stages of development (so that the latent heat is absorbed by the ice, instead of being converted to kinetic energy that would feed the positive feedback loop),[86] or blasting the cyclone apart with nuclear weapons.[88] Project Cirrus even involved throwing dry ice on a cyclone.[89] These approaches all suffer from one flaw above many others: tropical cyclones are simply too large and short-lived for any of the weakening techniques to be practical.[90]

Effects[edit]

Tropical cyclones out at sea cause large waves, heavy rain, flood and high winds, disrupting international shipping and, at times, causing shipwrecks.[91] Tropical cyclones stir up water, leaving a cool wake behind them, which causes the region to be less favorable for subsequent tropical cyclones.[37] On land, strong winds can damage or destroy vehicles, buildings, bridges, and other outside objects, turning loose debris into deadly flying projectiles. The storm surge, or the increase in sea level due to the cyclone, is typically the worst effect from landfalling tropical cyclones, historically resulting in 90% of tropical cyclone deaths.[92] The broad rotation of a landfalling tropical cyclone, and vertical wind shear at its periphery, spawns tornadoes. Tornadoes can also be spawned as a result of eyewall mesovortices, which persist until landfall.[93]

Over the past two centuries, tropical cyclones have been responsible for the deaths of about 1.9 million people worldwide. Large areas of standing water caused by flooding lead to infection, as well as contributing to mosquito-borne illnesses. Crowded evacuees in shelters increase the risk of disease propagation.[94] Tropical cyclones significantly interrupt infrastructure, leading to power outages, bridge destruction, and the hampering of reconstruction efforts.[94][95] On average, the Gulf and east coasts of the United States suffer approximately US $5 billion (1995 US $) in cyclone damage every year. Majority (83%) of tropical cyclone damage is caused by severe hurricanes, category 3 or greater. However, category 3 or greater hurricanes only account for about one-fifth of cyclones that make land every year.[96]

Although cyclones take an enormous toll in lives and personal property, they may be important factors in the precipitation regimes of places they impact, as they may bring much-needed precipitation to otherwise dry regions.[97] Tropical cyclones also help maintain the global heat balance by moving warm, moist tropical air to the middle latitudes and polar regions,[98] and by regulating the thermohaline circulation through upwelling.[99] The storm surge and winds of hurricanes may be destructive to human-made structures, but they also stir up the waters of coastal estuaries, which are typically important fish breeding locales. Tropical cyclone destruction spurs redevelopment, greatly increasing local property values.[100]

When hurricanes surge upon shore from the ocean, salt is introduced to many freshwater areas and raises the salinity levels too high for some habitats to withstand. Some are able to cope with the salt and recycle it back into the ocean, but others can not release the extra surface water quickly enough or do not have a large enough freshwater source to replace it. Because of this, some species of plants and vegetation die due to the excess salt.[101] In addition, hurricanes can carry toxins and acids onto shore when they make landfall. The flood water can pick up the toxins from different spills and contaminate the land that it passes over. The toxins are very harmful to the people and animals in the area, as well as the environment around them. The flooding water can also spark many dangerous oil spills.[102]

Observation and forecasting[edit]

Observation[edit]

Sunset view of Hurricane Isidore's rainbands photographed at 7,000 feet (2,100 m)

Intense tropical cyclones pose a particular observation challenge, as they are a dangerous oceanic phenomenon, and weather stations, being relatively sparse, are rarely available on the site of the storm itself. In general, surface observations are available only if the storm is passing over an island or a coastal area, or if there is a nearby ship. Real-time measurements are usually taken in the periphery of the cyclone, where conditions are less catastrophic and its true strength cannot be evaluated. For this reason, there are teams of meteorologists that move into the path of tropical cyclones to help evaluate their strength at the point of landfall.[103]

Tropical cyclones far from land are tracked by weather satellites capturing visible and infrared images from space, usually at half-hour to quarter-hour intervals. As a storm approaches land, it can be observed by land-based Doppler weather radar. Radar plays a crucial role around landfall by showing a storm's location and intensity every several minutes.[104]

In situ measurements, in real-time, can be taken by sending specially equipped reconnaissance flights into the cyclone. In the Atlantic basin, these flights are regularly flown by United States government hurricane hunters.[105] The aircraft used are WC-130 Hercules and WP-3D Orions, both four-engine turboprop cargo aircraft. These aircraft fly directly into the cyclone and take direct and remote-sensing measurements. The aircraft also launch GPS dropsondes inside the cyclone. These sondes measure temperature, humidity, pressure, and especially winds between flight level and the ocean's surface. A new era in hurricane observation began when a remotely piloted Aerosonde, a small drone aircraft, was flown through Tropical Storm Ophelia as it passed Virginia's Eastern Shore during the 2005 hurricane season. A similar mission was also completed successfully in the western Pacific ocean. This demonstrated a new way to probe the storms at low altitudes that human pilots seldom dare.[106]

A general decrease in error trends in tropical cyclone path prediction is evident since the 1970s

Forecasting[edit]

Because of the forces that affect tropical cyclone tracks, accurate track predictions depend on determining the position and strength of high- and low-pressure areas, and predicting how those areas will change during the life of a tropical system. The deep layer mean flow, or average wind through the depth of the troposphere, is considered the best tool in determining track direction and speed. If storms are significantly sheared, use of wind speed measurements at a lower altitude, such as at the 70 kPa pressure surface (3,000 metres or 9,800 feet above sea level) will produce better predictions. Tropical forecasters also consider smoothing out short-term wobbles of the storm as it allows them to determine a more accurate long-term trajectory.[107] High-speed computers and sophisticated simulation software allow forecasters to produce computer models that predict tropical cyclone tracks based on the future position and strength of high- and low-pressure systems. Combining forecast models with increased understanding of the forces that act on tropical cyclones, as well as with a wealth of data from Earth-orbiting satellites and other sensors, scientists have increased the accuracy of track forecasts over recent decades.[108] However, scientists are not as skillful at predicting the intensity of tropical cyclones.[109] The lack of improvement in intensity forecasting is attributed to the complexity of tropical systems and an incomplete understanding of factors that affect their development.

Classifications, terminology, and naming[edit]

Intensity classifications[edit]

Three tropical cyclones at different stages of development. The weakest (left) demonstrates only the most basic circular shape. A stronger storm (top right) demonstrates spiral banding and increased centralization, while the strongest (lower right) has developed an eye.

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. For example, if a tropical storm in the Northwestern Pacific reaches hurricane-strength winds on the Beaufort scale, it is referred to as a typhoon; if a tropical storm passes the same benchmark in the Northeast Pacific Basin, or in the North Atlantic, it is called a hurricane.[8] Neither "hurricane" nor "typhoon" is used in either the Southern Hemisphere or the Indian Ocean. In these basins, storms of a tropical nature are referred to as either tropical cyclones, severe tropical cyclones or very intense tropical cyclones.

As indicated in the table below, each basin uses a separate system of terminology, which can make comparisons between different basins difficult. In the Pacific Ocean, hurricanes from the Central North Pacific sometimes cross the 180th meridian into the Northwest Pacific, becoming typhoons (such as Hurricane/Typhoon Ioke in 2006); on rare occasions, the reverse will occur.[110] It should also be noted that typhoons with 1-minute sustained winds greater than 67 metres per second (m/s), over 150 miles per hour (240 km/h), are called Super Typhoons by the Joint Typhoon Warning Center.[111]

Tropical depression[edit]

A tropical depression is an organized system of clouds and thunderstorms with a defined, closed surface circulation and maximum sustained winds of less than 34 knots (63 km/h). It has no eye and does not typically have the organization or the spiral shape of more powerful storms. However, it is already a low-pressure system, hence the name "depression".[112] In the Philippines, the practice is to name tropical depressions from their own naming convention when the depressions are within the country's area of responsibility.[113]

Tropical storm[edit]

A tropical storm is an organized system of strong thunderstorms with a defined surface circulation and maximum sustained winds between 34 knots (63 km/h) and 64 knots (119 km/h). At this point, the distinctive cyclonic shape starts to develop, although an eye is not usually present. Government weather services first assign names to systems that reach this intensity (thus the term named storm).[112] Although tropical storms are less intense than a hurricane they can produce significant damage. The shear force of winds can blow off shingles and air borne object can cause damage to power lines, roofing and siding. More dangerous is the heavy rain fall causing inland flooding.[114] It is also at this point the nation hurricane center issues Watches and warnings for coastal areas.[75]

Hurricane or typhoon[edit]

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 of at least 34 metres per second (66 kn) or 74 miles per hour (119 km/h).[112] A cyclone of this intensity 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 16 kilometres (9.9 mi) to 80 kilometres (50 mi) wide in which the strongest thunderstorms and winds circulate around the storm's center. Maximum sustained winds in the strongest tropical cyclones have been estimated at about 85 metres per second (165 kn) or 314 kilometres per hour (195 mph).[115]

Tropical cyclone classifications [116][117]
The
Beaufort
scale
1-minute sustained winds 10-minute sustained winds NE Pacific &
N Atlantic
NHC/CPHC
NW Pacific
JTWC
NW Pacific
JMA
N Indian Ocean
IMD
SW Indian Ocean
MF
Australia & S Pacific
BOM/FMS[118]
0–7 <32 knots (37 mph; 59 km/h) <28 knots (32 mph; 52 km/h) Tropical Depression Tropical Depression Tropical Depression Depression Zone of Disturbed Weather Tropical Disturbance
Tropical Depression
Tropical Low
7 33 knots (38 mph; 61 km/h) 28–29 knots (32–33 mph; 52–54 km/h) Deep Depression Tropical Disturbance
8 34–37 knots (39–43 mph; 63–69 km/h) 30–33 knots (35–38 mph; 56–61 km/h) Tropical Storm Tropical Storm Tropical Depression
9-10 38–54 knots (44–62 mph; 70–100 km/h) 34–47 knots (39–54 mph; 63–87 km/h) Tropical Storm Cyclonic Storm Moderate Tropical Storm Category 1
tropical cyclone
11 55–63 knots (63–72 mph; 102–117 km/h) 48–55 knots (55–63 mph; 89–102 km/h) Severe Tropical Storm Severe Cyclonic Storm Severe Tropical Storm Category 2
tropical cyclone
12+ 64–71 knots (74–82 mph; 119–131 km/h) 56–63 knots (64–72 mph; 104–117 km/h) Category 1 hurricane Typhoon
72–82 knots (83–94 mph; 133–152 km/h) 64–72 knots (74–83 mph; 119–133 km/h) Typhoon Very Severe
Cyclonic Storm
Tropical Cyclone Category 3 severe
tropical cyclone
83–95 knots (96–109 mph; 154–176 km/h) 73–83 knots (84–96 mph; 135–154 km/h) Category 2 hurricane
96–97 knots (110–112 mph; 178–180 km/h) 84–85 knots (97–98 mph; 156–157 km/h) Category 3 hurricane
98–112 knots (113–129 mph; 181–207 km/h) 86–98 knots (99–113 mph; 159–181 km/h) Intense Tropical Cyclone Category 4 severe
tropical cyclone
113–122 knots (130–140 mph; 209–226 km/h) 99–107 knots (114–123 mph; 183–198 km/h) Category 4 hurricane
123–129 knots (142–148 mph; 228–239 km/h) 108–113 knots (124–130 mph; 200–209 km/h) Category 5 severe
tropical cyclone
130–136 knots (150–157 mph; 241–252 km/h) 114–119 knots (131–137 mph; 211–220 km/h) Super Typhoon Super Cyclonic Storm Very Intense Tropical Cyclone
>137 knots (158 mph; 254 km/h) >120 knots (140 mph; 220 km/h) Category 5 hurricane

Origin of storm terms[edit]

Taipei 101 endures a typhoon in 2005

The word typhoon, which is used today in the Northwest Pacific, may be derived from Arabic ţūfān (طوفان) (similar in Hindi/Urdu and Persian), which in turn originates from Greek Typhon (Τυφών), a monster from Greek mythology associated with storms.[119] The related Portuguese word tufão, used in Portuguese for typhoons, is also derived from Typhon.[120] The word is also similar to Chinese "táifēng" (Simplified Chinese: 台风) (fēng = wind), "toifung" in Cantonese (Traditional Chinese: 颱風), "taifū" (台風) in Japanese, and "taepung" (태풍) in Korean.

The word hurricane, used in the North Atlantic and Northeast Pacific, is derived from huracán, the Spanish word for the Carib/Taino storm god, Juracán. This god is believed by scholars to have been at least partially derived from the Mayan creator god, Huracan. Huracan was believed by the Maya to have created dry land out of the turbulent waters. The god was also credited with later destroying the "wooden people", the precursors to the "maize people", with an immense storm and flood.[121][122] Huracan is also the source of the word orcan, another word for a particularly strong European windstorm.[122]

Naming[edit]

Storms reaching tropical storm strength were initially given names to eliminate confusion when there are multiple systems in any individual basin at the same time, which assists in warning people of the coming storm.[123] In 1953, the United States abandoned a plan to name hurricanes using a phonetic alphabet, and began using women's names. The practice of using women's names exclusively came to an end in 1978, when both men's and women's names were added to the Eastern North Pacific storm lists. The lists for the Atlantic and Gulf of Mexico followed in 1979.[124] In most cases, a tropical cyclone retains its name throughout its life; however, under special circumstances, tropical cyclones may be renamed while active. These names are taken from lists that vary from region to region and are usually drafted a few years ahead of time. The lists are decided on, depending on the regions, either by committees of the World Meteorological Organization (called primarily to discuss many other issues) or by national weather offices involved in the forecasting of the storms. Within all basins except for the Southwestern or North Indian Ocean, the names of particularly destructive or deadly storms may be retired and replaced with a new name.

According to a study done by researchers at the University of Illinois hurricanes with feminine names cause up to three times more fatalities because people don't see them as threatening compared to hurricanes with masculine names. Every hurricane in the US between 1950 and 2012 except for Hurricane Katrina (2005) and Hurricane Audrey (1957) were studied and results show that hurricanes with masculine names cause 15.15 deaths and hurricanes with feminine names caused 41.84 deaths. [125]

Notable tropical cyclones[edit]

Tropical cyclones that cause extreme destruction are rare, although when they occur, they can cause great amounts of damage or thousands of fatalities. The 1970 Bhola cyclone is the deadliest tropical cyclone on record, killing more than 300,000 people[126] and potentially as many as 1 million[127] after striking the densely populated Ganges Delta region of Bangladesh on November 13, 1970. Its powerful storm surge was responsible for the high death toll.[126] The North Indian cyclone basin has historically been the deadliest basin.[94][128] Elsewhere, Typhoon Nina killed nearly 100,000 in China in 1975 due to a 100-year flood that caused 62 dams including the Banqiao Dam to fail.[129] The Great Hurricane of 1780 is the deadliest North Atlantic hurricane on record, killing about 22,000 people in the Lesser Antilles.[130] A tropical cyclone does need not be particularly strong to cause memorable damage, primarily if the deaths are from rainfall or mudslides. Tropical Storm Thelma in November 1991 killed thousands in the Philippines,[131] while in 1982, the unnamed tropical depression that eventually became Hurricane Paul killed around 1,000 people in Central America.[132]

Hurricane Katrina is estimated as the costliest tropical cyclone worldwide,[133] causing $81.2 billion in property damage (2008 USD)[134] with overall damage estimates exceeding $100 billion (2005 USD).[133] Katrina killed at least 1,836 people after striking Louisiana and Mississippi as a major hurricane in August 2005.[134] Hurricane Sandy is the second most destructive tropical cyclone in U.S history, with damages totaling $68 billion (2012 USD), and with damage costs at $37.5 billion (2012 USD), Hurricane Ike is the third most destructive tropical cyclone in U.S history. The Galveston Hurricane of 1900 is the deadliest natural disaster in the United States, killing an estimated 6,000 to 12,000 people in Galveston, Texas.[135] Hurricane Mitch caused more than 10,000 fatalities in Latin America. Hurricane Iniki in 1992 was the most powerful storm to strike Hawaii in recorded history, hitting Kauai as a Category 4 hurricane, killing six people, and causing U.S. $3 billion in damage.[136] Kauai was also struck by Hurricanes Dot (1959) and Iwa (1982) (see List of Hawaii hurricanes). Other destructive Eastern Pacific hurricanes include Pauline and Kenna, both causing severe damage after striking Mexico as major hurricanes.[137][138] In March 2004, Cyclone Gafilo struck northeastern Madagascar as a powerful cyclone, killing 74, affecting more than 200,000, and becoming the worst cyclone to affect the nation for more than 20 years.[139]

Hurricane Sandy which hit the United States east coast in late October 2012, caused unprecedented damage, flooded subways, closed down all major airports, resulted in cancellation of over 20,000 flights,[140][141] costing the aviation industry nearly 200 million dollars.[142] It claimed more than one-hundred lives.[143][144] Eleven states and the District of Columbia were declared disaster states.[145] Estimates for the damage cost vary from 50–70 billion dollars.[146][147]

The relative sizes of Typhoon Tip, Cyclone Tracy, and the Contiguous United States

The most intense storm on record was Typhoon Tip in the northwestern Pacific Ocean in 1979, which reached a minimum pressure of 870 hectopascals (26 inHg) and maximum sustained wind speeds of 165 knots (85 m/s) or 190 miles per hour (310 km/h).[148] Tip, however, does not solely hold the record for fastest sustained winds in a cyclone. Typhoon Keith in the Pacific and Hurricane Allen in the North Atlantic currently share this record with Tip.[149] Typhoon Nancy in 1961 had recorded wind speeds of 185 knots (95 m/s) or 215 miles per hour (346 km/h), but recent research indicates that wind speeds from the 1940s to the 1960s were gauged too high, and this is no longer considered the storm with the highest wind speeds on record.[115] Likewise, a surface-level gust caused by Typhoon Paka on Guam was recorded at 205 knots (105 m/s) or 235 miles per hour (378 km/h). Had it been confirmed, it would be the strongest non-tornadic wind ever recorded on the Earth's surface, but the reading had to be discarded since the anemometer was damaged by the storm.[150]

In addition to being the most intense tropical cyclone on record based on pressure, Tip was the largest cyclone on record, with tropical storm-force winds 2,170 kilometres (1,350 mi) in diameter. The smallest storm on record, Tropical Storm Marco, formed during October 2008, and made landfall in Veracruz. Marco generated tropical storm-force winds only 37 kilometres (23 mi) in diameter.[151]

Hurricane John is the longest-lasting tropical cyclone on record, lasting 31 days in 1994. Before the advent of satellite imagery in 1961, however, many tropical cyclones were underestimated in their durations.[152] John is also the longest-tracked tropical cyclone in the Northern Hemisphere on record, which had a path of 8,250 mi (13,280 km).[153] Cyclone Rewa of the 1993-94 South Pacific and Australian region cyclone seasons had one of the longest tracks observed within the Southern Hemisphere, travelling a distance of over 5,545 mi (8,920 km) during December 1993 and January 1994.[153]

Changes caused by El Niño-Southern Oscillation[edit]

Most tropical cyclones form on the side of the subtropical ridge closer to the equator, then move poleward past the ridge axis before recurving into the main belt of the Westerlies.[154] When the subtropical ridge position shifts due to El Niño, so will the preferred tropical cyclone tracks. Areas west of Japan and Korea tend to experience much fewer September–November tropical cyclone impacts during El Niño and neutral years. During El Niño years, the break in the subtropical ridge tends to lie near 130°E which would favor the Japanese archipelago.[155] During El Niño years, Guam's chance of a tropical cyclone impact is one-third more likely than of the long term average.[156] The tropical Atlantic ocean experiences depressed activity due to increased vertical wind shear across the region during El Niño years.[157] During La Niña years, the formation of tropical cyclones, along with the subtropical ridge position, shifts westward across the western Pacific ocean, which increases the landfall threat to China and much greater intensity in the Philippines.[155]

Long-term activity trends[edit]

Atlantic Multidecadal Cycle since 1950, using accumulated cyclone energy (ACE)
Atlantic Multidecadal Oscillation Timeseries, 1856–2013

While the number of storms in the Atlantic has increased since 1995, there is no obvious global trend; the annual number of tropical cyclones worldwide remains about 87 ± 10 (Between 77 and 97 tropical cyclones annually). However, the ability of climatologists to make long-term data analysis in certain basins is limited by the lack of reliable historical data in some basins, primarily in the Southern Hemisphere.[158] In spite of that, there is some evidence that the intensity of hurricanes is increasing. Kerry Emanuel stated, "Records of hurricane activity worldwide show an upswing of both the maximum wind speed in and the duration of hurricanes. The energy released by the average hurricane (again considering all hurricanes worldwide) seems to have increased by around 70% in the past 30 years or so, corresponding to about a 15% increase in the maximum wind speed and a 60% increase in storm lifetime."[159]

Atlantic storms are becoming more destructive financially, as evidenced by the fact that five of the ten most expensive storms in United States history have occurred since 1990. According to the World Meteorological Organization, "recent increase in societal impact from tropical cyclones has been caused largely by rising concentrations of population and infrastructure in coastal regions."[160] Pielke et al. (2008) normalized mainland U.S. hurricane damage from 1900–2005 to 2005 values and found no remaining trend of increasing absolute damage. The 1970s and 1980s were notable because of the extremely low amounts of damage compared to other decades. The decade 1996–2005 was the second most damaging among the past 11 decades, with only the decade 1926–1935 surpassing its costs. The most damaging single storm is the 1926 Miami hurricane, with $157 billion of normalized damage.[161]

Often in part because of the threat of hurricanes, many coastal regions had sparse population between major ports until the advent of automobile tourism; therefore, the most severe portions of hurricanes striking the coast may have gone unmeasured in some instances. The combined effects of ship destruction and remote landfall severely limit the number of intense hurricanes in the official record before the era of hurricane reconnaissance aircraft and satellite meteorology. Although the record shows a distinct increase in the number and strength of intense hurricanes, therefore, experts regard the early data as suspect.[162]

The number and strength of Atlantic hurricanes may undergo a 50–70 year cycle, also known as the Atlantic Multidecadal Oscillation. Nyberg et al. reconstructed Atlantic major hurricane activity back to the early 18th century and found five periods averaging 3–5 major hurricanes per year and lasting 40–60 years, and six other averaging 1.5–2.5 major hurricanes per year and lasting 10–20 years. These periods are associated with the Atlantic multidecadal oscillation. Throughout, a decadal oscillation related to solar irradiance was responsible for enhancing/dampening the number of major hurricanes by 1–2 per year.[163]

Although more common since 1995, few above-normal hurricane seasons occurred during 1970–94.[164] Destructive hurricanes struck frequently from 1926 to 1960, including many major New England hurricanes. Twenty-one Atlantic tropical storms formed in 1933, a record only recently exceeded in 2005, which saw 28 storms. Tropical hurricanes occurred infrequently during the seasons of 1900–25; however, many intense storms formed during 1870–99. During the 1887 season, 19 tropical storms formed, of which a record 4 occurred after November 1 and 11 strengthened into hurricanes. Few hurricanes occurred in the 1840s to 1860s; however, many struck in the early 19th century, including an 1821 storm that made a direct hit on New York City. Some historical weather experts say these storms may have been as high as Category 4 in strength.[165]

These active hurricane seasons predated satellite coverage of the Atlantic basin. Before the satellite era began in 1960, tropical storms or hurricanes went undetected unless a reconnaissance aircraft encountered one, a ship reported a voyage through the storm, or a storm hit land in a populated area.[162]

Proxy records based on paleotempestological research have revealed that major hurricane activity along the Gulf of Mexico coast varies on timescales of centuries to millennia.[166][167] Few major hurricanes struck the Gulf coast during 3000–1400 BC and again during the most recent millennium. These quiescent intervals were separated by a hyperactive period during 1400 BC and 1000 AD, when the Gulf coast was struck frequently by catastrophic hurricanes and their landfall probabilities increased by 3–5 times. This millennial-scale variability has been attributed to long-term shifts in the position of the Azores High,[167] which may also be linked to changes in the strength of the North Atlantic Oscillation.[168]

According to the Azores High hypothesis, an anti-phase pattern is expected to exist between the Gulf of Mexico coast and the Atlantic coast. During the quiescent periods, a more northeasterly position of the Azores High would result in more hurricanes being steered towards the Atlantic coast. During the hyperactive period, more hurricanes were steered towards the Gulf coast as the Azores High was shifted to a more southwesterly position near the Caribbean. Such a displacement of the Azores High is consistent with paleoclimatic evidence that shows an abrupt onset of a drier climate in Haiti around 3200 14C years BP,[169] and a change towards more humid conditions in the Great Plains during the late-Holocene as more moisture was pumped up the Mississippi Valley through the Gulf coast. Preliminary data from the northern Atlantic coast seem to support the Azores High hypothesis. A 3000-year proxy record from a coastal lake in Cape Cod suggests that hurricane activity increased significantly during the past 500–1000 years, just as the Gulf coast was amid a quiescent period of the last millennium.

Global warming[edit]

According to IPCC SREX 2012, "attribution of single extreme events to anthropogenic climate change is challenging".[170] On one hand, the report said that there is "medium evidence" that long-term trends in normalized losses have not been attributed to tropical and extratropical [winter] storms. On the other hand, the report also noted that much more research is needed in part due to "confounding factors" that might have increased losses, such as increased population and development in at-risk areas, and those that might have decreased losses, such as better forecasting, emergency alert systems, emergency management, building codes, and near-instantaneous media coverage of weather emergencies.[171]

Some experts who agree that we can not yet detect any increase in frequency or intensity of tropical cyclones include Thomas Knutson,[172] and Roger Pielke Jr..[173]

Others say that there is evidence for a causal connection. The U.S. National Oceanic and Atmospheric Administration Geophysical Fluid Dynamics Laboratory performed a simulation to determine if there is a statistical trend in the frequency or strength of tropical cyclones over time. The simulation concluded "the strongest hurricanes in the present climate may be upstaged by even more intense hurricanes over the next century as the earth's climate is warmed by increasing levels of greenhouse gases in the atmosphere".[174]

In another simulation done by Kerry Emanuel, application of a tropical cyclone downscaling technique to six CMIP5-generation global climate models run under historical conditions and under the RCP8.5 emissions projection indicates an increase in global tropical cyclone activity, most evident in the North Pacific region but also noticeable in the North Atlantic and South Indian Oceans. In these regions, both the frequency and intensity of tropical cyclones are projected to increase. This result contrasts with the result of applying the same downscaling technique to CMIP3-generation models, which generally predict a small decrease of global tropical cyclone frequency.[175]

Costliest U.S. Atlantic hurricanes 1900–2010
Total estimated property damage, adjusted for wealth normalization[161][176]
Rank Hurricane Season Cost (2010 USD)
1 "Miami" 1926 $164.8 billion
2 Katrina 2005 $113.4 billion
3 "Galveston" 1900 $104.3 billion
4 "Galveston" 1915 $ 71.3 billion
5 Andrew 1992 $ 58.5 billion
6 "New England" 1938 $ 41.1 billion
7 "Cuba–Florida" 1944 $ 40.6 billion
8 "Okeechobee" 1928 $ 35.2 billion
9 Ike 2008 $ 29.5 billion
10 Donna 1960 $ 28.1 billion
Main article: List of costliest Atlantic hurricanes
Costliest US Atlantic Hurricanes 1900–2010

In an article in Nature, meteorology professor Kerry Emanuel stated that potential hurricane destructiveness, a measure combining hurricane strength, duration, and frequency, "is highly correlated with tropical sea surface temperature, reflecting well-documented climate signals, including multidecadal oscillations in the North Atlantic and North Pacific, and global warming". Emanuel predicted "a substantial increase in hurricane-related losses in the twenty-first century".[177] In more recent work, Emanuel states that new climate modeling data indicates "global warming should reduce the global frequency of hurricanes."[178] According to the Houston Chronicle, the new work suggests that, even in a dramatically warming world, hurricane frequency and intensity may not substantially rise during the next two centuries.[179]

P.J. Webster and others published an article in Science examining the "changes in tropical cyclone number, duration, and intensity" over the past 35 years, the period when satellite data has been available. Their main finding was although the number of cyclones decreased throughout the planet excluding the north Atlantic Ocean, there was a great increase in the number and proportion of very strong cyclones.[180]

The strength of the reported effect is surprising in light of modeling studies[181] that predict only a one-half category increase in storm intensity as a result of a ~2 °C (3.6 °F) global warming. Such a response would have predicted only a ~10% increase in Emanuel's potential destructiveness index during the 20th century rather than the ~75–120% increase he reported.[177] Second, after adjusting for changes in population and inflation, and despite a more than 100% increase in Emanuel's potential destructiveness index, no statistically significant increase in the monetary damages resulting from Atlantic hurricanes has been found.[161][182]

Sufficiently warm sea surface temperatures are considered vital to the development of tropical cyclones.[183] Although neither study can directly link hurricanes with global warming, the increase in sea surface temperatures is believed to be due to both global warming and natural variability, e.g. the hypothesized Atlantic Multidecadal Oscillation (AMO), although an exact attribution has not been defined.[184] However, recent temperatures are the warmest ever observed for many ocean basins.[177]

In February 2007, the United Nations Intergovernmental Panel on Climate Change released its fourth assessment report on climate change. The report noted many observed changes in the climate, including atmospheric composition, global average temperatures, ocean conditions, and others. The report concluded the observed increase in tropical cyclone intensity is larger than climate models predict. In addition, the report considered that it is likely that storm intensity will continue to increase through the 21st century, and declared it more likely than not that there has been some human contribution to the increases in tropical cyclone intensity.[185] However, there is no universal agreement about the magnitude of the effects anthropogenic global warming has on tropical cyclone formation, track, and intensity. For example, critics such as Chris Landsea assert that man-made effects would be "quite tiny compared to the observed large natural hurricane variability".[186] A statement by the American Meteorological Society on February 1, 2007 stated that trends in tropical cyclone records offer "evidence both for and against the existence of a detectable anthropogenic signal" in tropical cyclogenesis.[187] Although many aspects of a link between tropical cyclones and global warming are still being "hotly debated",[188] a point of agreement is that the strength of destructiveness no individual tropical cyclone or season can be attributed entirely to global warming.[184][188] Research reported in the September 3, 2008 issue of Nature found that the strongest tropical cyclones are getting stronger, in particular over the North Atlantic and Indian oceans. Wind speeds for the strongest tropical storms increased from an average of 230 kilometres per hour (140 mph) in 1981 to 251 kilometres per hour (156 mph) in 2006, while the ocean temperature, averaged globally over all the regions where tropical cyclones form, increased from 28.2 °C (82.8 °F) to 28.5 °C (83.3 °F) during this period.[189][190]

Related cyclone types[edit]

Gustav on September 9, the first system to be given a name as a subtropical cyclone

In addition to tropical cyclones, there are two other classes of cyclones within the spectrum of cyclone types. These kinds of cyclones, known as extratropical cyclones and subtropical cyclones, can be stages a tropical cyclone passes through during its formation or dissipation.[191] An extratropical cyclone is a storm that derives energy from horizontal temperature differences, which are typical in higher latitudes. A tropical cyclone can become extratropical as it moves toward higher latitudes if its energy source changes from heat released by condensation to differences in temperature between air masses; although not as frequently, an extratropical cyclone can transform into a subtropical storm, and from there into a tropical cyclone.[192] From space, extratropical storms have a characteristic "comma-shaped" cloud pattern.[193] Extratropical cyclones can also be dangerous when their low-pressure centers cause powerful winds and high seas.[194]

A subtropical cyclone is a weather system that has some characteristics of a tropical cyclone and some characteristics of an extratropical cyclone. They can form in a wide band of latitudes, from the equator to 50°. Although subtropical storms rarely have hurricane-force winds, they may become tropical in nature as their cores warm.[195] From an operational standpoint, a tropical cyclone is usually not considered to become subtropical during its extratropical transition.[196]

In popular culture[edit]

In popular culture, tropical cyclones have made several appearances in different types of media, including films, books, television, music, and electronic games.[197] These media often portray tropical cyclones that are either entirely fictional or based on real events.[197] For example, George Rippey Stewart's Storm, a best-seller published in 1941, is thought to have influenced meteorologists on their decision to assign female names to Pacific tropical cyclones.[198] Another example is the hurricane in The Perfect Storm, which describes the sinking of the Andrea Gail by the 1991 Perfect Storm.[199] Hypothetical hurricanes have been featured in parts of the plots of series such as The Simpsons, Invasion, Family Guy, Seinfeld, Dawson's Creek, Burn Notice and CSI: Miami.[197][200][201][202][203][204] The 2004 film The Day After Tomorrow includes several mentions of actual tropical cyclones and features fantastical "hurricane-like", albeit non-tropical, Arctic storms.[205][206]

See also[edit]

References[edit]

Notes

  1. ^ "hurricane: definition of hurricane in Oxford dictionary (British & World English) (US)". Retrieved October 1, 2014. 
  2. ^ "Hurricane - Definition and More from the Free Merriam-Webster Dictionary". Retrieved October 1, 2014. 
  3. ^ "Definition of "hurricane" - Collins English Dictionary". Retrieved October 1, 2014. 
  4. ^ "The only difference between a hurricane, a cyclone, and a typhoon is the location where the storm occurs". Retrieved October 1, 2014. 
  5. ^ a b Zhang, H. et al. (1998). "Tropical cyclones and global climate change: A post-IPCC assessment". Bulletin of the American Meteorological Society 79 (79): 19–38. Bibcode:1998BAMS...79...19H. doi:10.1175/1520-0477(1998)079<0019:TCAGCC>2.0.CO;2. Retrieved June 3, 2013. 
  6. ^ Symonds, Steve (November 17, 2003). "Highs and Lows". Wild Weather (Australian Broadcasting Corporation). Archived from the original on October 11, 2007. Retrieved March 23, 2007. 
  7. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: What is an extra-tropical cyclone?". National Oceanic and Atmospheric Administration. Retrieved March 23, 2007. 
  8. ^ a b c d e National Hurricane Center (2005). "Glossary of NHC/TPC Terms". National Oceanic and Atmospheric Administration. Retrieved November 29, 2006. 
  9. ^ Marine Meteorology Division. "Cirrus Cloud Detection" (PDF). Satellite Product Tutorials. Monterey, CA: United States Naval Research Laboratory. p. 1. Retrieved June 4, 2013. 
  10. ^ a b Frank, W. M. (1977). "The structure and energetics of the tropical cyclone I. Storm structure". Monthly Weather Review 105 (9): 1119–1135. Bibcode:1977MWRv..105.1119F. doi:10.1175/1520-0493(1977)105<1119:TSAEOT>2.0.CO;2. Retrieved June 4, 2013. 
  11. ^ a b National Weather Service (October 19, 2005). "Tropical Cyclone Structure". JetStream — An Online School for Weather. National Oceanic & Atmospheric Administration. Retrieved May 7, 2009. 
  12. ^ Pasch, Richard J.; Eric S. Blake, Hugh D. Cobb III, and David P. Roberts (September 28, 2006). "Tropical Cyclone Report: Hurricane Wilma: 15–25 October 2005" (PDF). National Hurricane Center. Retrieved December 14, 2006. 
  13. ^ Lander, Mark A. (January 1999). "A Tropical Cyclone with a Very Large Eye". Monthly Weather Review 127 (1): 137. Bibcode:1999MWRv..127..137L. doi:10.1175/1520-0493(1999)127<0137:ATCWAV>2.0.CO;2. ISSN 1520-0493. Retrieved December 14, 2006. 
  14. ^ Pasch, Richard J. and Lixion A. Avila (May 1999). "Atlantic Hurricane Season of 1996" (PDF). Monthly Weather Review 127 (5): 581–610. Bibcode:1999MWRv..127..581P. doi:10.1175/1520-0493(1999)127<0581:AHSO>2.0.CO;2. ISSN 1520-0493. Retrieved December 14, 2006. 
  15. ^ American Meteorological Society. "AMS Glossary: C". Glossary of Meteorology. Allen Press. Retrieved December 14, 2006. 
  16. ^ Atlantic Oceanographic and Hurricane Research Division. "Frequently Asked Questions: What are "concentric eyewall cycles" (or "eyewall replacement cycles") and why do they cause a hurricane's maximum winds to weaken?". National Oceanic and Atmospheric Administration. Retrieved December 14, 2006. 
  17. ^ a b "Q: What is the average size of a tropical cyclone?". Joint Typhoon Warning Center. 2009. Retrieved May 7, 2009. 
  18. ^ "Global Guide to Tropical Cyclone Forecasting: chapter 2: Tropical Cyclone Structure". Bureau of Meteorology. May 7, 2009. Retrieved May 6, 2009. 
  19. ^ a b D. R. Chavas and K. A. Emanuel (September 2010). "A QuikSCAT climatology of tropical cyclone size". Geophysical Research Letters 37 (18): n/a. Bibcode:2010GeoRL..3718816C. doi:10.1029/2010GL044558. Retrieved June 11, 2013. 
  20. ^ K. S. Liu and Johnny C. L. Chan (December 1999). "Size of Tropical Cyclones as Inferred from ERS-1 and ERS-2 Data". Monthly Weather Review 127 (12): 2992. Bibcode:1999MWRv..127.2992L. doi:10.1175/1520-0493(1999)127<2992:SOTCAI>2.0.CO;2. ISSN 1520-0493. Retrieved February 24, 2008. 
  21. ^ Merrill, Robert T (December 14, 1983). "A comparison of Large and Small Tropical cyclones". Monthly Weather Review (American Meteorological Society) 112 (7): 1408. doi:10.1175/1520-0493(1984)112<1408:ACOLAS>2.0.CO;2. Retrieved May 6, 2009. 
  22. ^ J. L. Irish, D. T. Resio, and J. J. Ratcliff (September 2008). "The Influence of Storm Size on Hurricane Surge". Journal of Physical Oceanography 38 (9): 2003. Bibcode:2008JPO....38.2003I. doi:10.1175/2008JPO3727.1. Retrieved June 11, 2013. 
  23. ^ D. E. Waco (October 1970). "Temperatures and turbulence at tropopause levels over hurricane Beulah (1967)". Monthly Weather Review 98 (10). doi:10.1175/1520-0493(1970)098<0749:TATATL>2.3.CO;2. Retrieved August 15, 2013. 
  24. ^ Kerry Emanuel (February 8, 2006). "Anthropogenic Effects on Tropical Cyclone Activity.". Massachusetts Institute of Technology. Retrieved May 7, 2009. 
  25. ^ a b Emanuel, K.A. (1986). "An air-sea interaction theory for tropical cyclones. Part I: Steady-state maintenance". Journal of the Atmospheric Sciences 43 (6): 585–605. Bibcode:1986JAtS...43..585E. doi:10.1175/1520-0469(1986)043<0585:AASITF>2.0.CO;2. ISSN 1520-0469. Retrieved June 4, 2013. 
  26. ^ a b "NOAA FAQ: How much energy does a hurricane release?". National Oceanic & Atmospheric Administration. August 2001. Retrieved June 30, 2009. 
  27. ^ "Hurricanes: Keeping an eye on weather's biggest bullies.". University Corporation for Atmospheric Research. March 31, 2006. Retrieved May 7, 2009. 
  28. ^ Barnes, Gary. "Hurricanes and the equator". University of Hawaii. Retrieved August 30, 2013. 
  29. ^ Bister, M. and K.A. Emanuel (1998). "Dissipative heating and hurricane intensity". Meteorology and Atmospheric Physics 65 (3–4): 233–240. Bibcode:1998MAP....65..233B. doi:10.1007/BF01030791. Retrieved June 12, 2013. 
  30. ^ Emanuel, K.A. (April 2000). "A statistical analysis of tropical cyclone intensity". Monthly Weather Review 128 (4): 1139–1152. Bibcode:2000MWRv..128.1139E. doi:10.1175/1520-0493(2000)128<1139:ASAOTC>2.0.CO;2. ISSN 1520-0493. Retrieved June 12, 2013. 
  31. ^ Knutson, T. R. et al. (February 2010). "Tropical cyclones and climate change". Nature Geoscience 3 (3): 157–163. Bibcode:2010NatGe...3..157K. doi:10.1038/ngeo779. ISSN 1520-0493. Retrieved June 12, 2013. 
  32. ^ a b Bister, M. and K.A. Emanuel (December 2002). "Low frequency variability of tropical cyclone potential intensity 1. Interannual to interdecadal variability". Journal of Geophysical Research: Atmospheres 107 (D24): ACL 26–1–ACL 26–15. doi:10.1029/2001JD000776. 
  33. ^ Powell, M. D., Vickery, P. J., and T. A. Reinhold (March 2003). "Reduced drag coefficient for high wind speeds in tropical cyclones". Nature 422 (6929): 279–283. Bibcode:2003Natur.422..279P. doi:10.1038/nature01481. Retrieved June 12, 2013. 
  34. ^ Bell, M. M., Montgomery, M. T., and K. A. Emanuel (November 2012). "Air–sea enthalpy and momentum exchange at major hurricane wind speeds observed during CBLAST". Journal of the Atmospheric Sciences 69 (11): 3197–3222. Bibcode:2012JAtS...69.3197B. doi:10.1175/JAS-D-11-0276.1. Retrieved June 12, 2013. 
  35. ^ Emanuel, K. A. and A. H. Sobel (2013). "Response of tropical sea surface temperature, precipitation, and tropical cyclone‐related variables to changes in global and local forcing". Journal of Advances in Modeling Earth Systems 5 (2): 447. doi:10.1002/jame.20032. 
  36. ^ Sobel, A. H., and C. S. Bretherton (December 2000). "Modeling tropical precipitation in a single column". Journal of Climate 13 (24): 4378–4392. Bibcode:2000JCli...13.4378S. doi:10.1175/1520-0442(2000)013<4378:MTPIAS>2.0.CO;2. ISSN 1520-0442. Retrieved June 12, 2013. 
  37. ^ a b Eric A. D'Asaro and Peter G. Black. (2006). "J8.4 Turbulence in the Ocean Boundary Layer Below Hurricane Dennis" (PDF). University of Washington. Retrieved February 22, 2008. [dead link]
  38. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: What regions around the globe have tropical cyclones and who is responsible for forecasting there?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  39. ^ "Regional Specialized Meteorological Center". Tropical Cyclone Program (TCP). World Meteorological Organization. April 25, 2006. Retrieved November 5, 2006. 
  40. ^ "Joint Typhoon Warning Center Mission Statement.". Joint Typhoon Warning Center. November 9, 2007. Archived from the original on April 9, 2008. Retrieved May 7, 2009. 
  41. ^ "Mission Vision". Philippine Atmospheric, Geophysical and Astronomical Services Administration. February 24, 2008. Archived from the original on February 24, 2009. Retrieved May 7, 2009. 
  42. ^ "Canadian Hurricane Center". Canadian Hurricane Center. February 24, 2008. Retrieved May 7, 2009. 
  43. ^ Marcelino, Emerson Vieira; Isabela Pena Viana de Oliveira Marcelino; Frederico de Moraes Rudorff (2004). "Cyclone Catarina: Damage and Vulnerability Assessment" (PDF). Santa Catarina Federal University. Retrieved December 24, 2006. 
  44. ^ a b c d Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: When is hurricane season?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  45. ^ McAdie, Colin (May 10, 2007). "Tropical Cyclone Climatology". National Hurricane Center. Retrieved June 9, 2007. 
  46. ^ "Tropical Cyclone Operational Plan for the Southeastern Indian Ocean and the South Pacific Oceans". World Meteorological Organization. March 10, 2009. Retrieved May 6, 2009. 
  47. ^ a b c d e f Hurricane Research Division. "Frequently Asked Questions: What are the average, most, and least tropical cyclones occurring in each basin?". National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory. Retrieved December 5, 2012. 
  48. ^ The RA I Tropical Cyclone Committee (2012). "Tropical Cyclone Operational Plan: 2012". World Meteorological Organisation. p. 11. Retrieved December 5, 2012. 
  49. ^ National Climate Prediction Centre (October 14, 2013). "2013/14 Australian Tropical Cyclone season outlook". Australian Bureau of Meteorology. Retrieved October 14, 2013. 
  50. ^ RSMC Nadi – Tropical Cyclone Centre (October 18, 2012). "2012/13 Tropical Cyclone Season Outlook in the Regional Specialised Meteorological Centre Nadi – Tropical Cyclone Centre Area of Responsibility". Fiji Meteorological Service. Retrieved December 5, 2012. 
  51. ^ Ross., Simon (1998). Natural Hazards. (Illustrated ed.). Nelson Thornes. p. 96. ISBN 978-0-7487-3951-6. Retrieved May 7, 2009. 
  52. ^ a b c d e f Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: How do tropical cyclones form?". National Oceanic and Atmospheric Administration. Retrieved July 26, 2006. 
  53. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: Why do tropical cyclones require 80 °F (27 °C) ocean temperatures to form?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  54. ^ Kazuyoshi Kikuchi, Bin Wang, and Hironori Fudeyasu (2009). "Genesis of tropical cyclone Nargis revealed by multiple satellite observations". Geophysical Research Letters 36 (6): L06811. Bibcode:2009GeoRL..3606811K. doi:10.1029/2009GL037296. 
  55. ^ Fritz Korek (November 21, 2000). "Marine Meteorological Glossary". Marine Knowledge Centre. Retrieved May 6, 2009. 
  56. ^ "Formation of Tropical Cyclones". Philippine Atmospheric, Geophysical and Astronomical Services Administration. 2008. Retrieved May 6, 2009. 
  57. ^ DeCaria, Alex (2005). "Lesson 5 – Tropical Cyclones: Climatology.". ESCI 344 – Tropical Meteorology. Millersville University. Archived from the original on May 7, 2008. Retrieved February 22, 2008. 
  58. ^ a b Avila, Lixion, Lixion A.; Richard Pasch (March 1995). "Atlantic tropical systems of 1993" (PDF). Monthly Weather Review 123 (3): 887–896. Bibcode:1995MWRv..123..887A. doi:10.1175/1520-0493(1995)123<0887:ATSO>2.0.CO;2. ISSN 1520-0493. Retrieved July 25, 2006. 
  59. ^ a b Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: What is an easterly wave?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  60. ^ Landsea, Chris (June 1993). "A Climatology of Intense (or Major) Atlantic Hurricanes" (PDF). Monthly Weather Review 121 (6): 1703–1713. Bibcode:1993MWRv..121.1703L. doi:10.1175/1520-0493(1993)121<1703:ACOIMA>2.0.CO;2. ISSN 1520-0493. Retrieved March 25, 2006. 
  61. ^ Dowdy Andrew, J. et al. Tropical Cyclone Climatology of the South Pacific Ocean and its Relationshiop to El Nino-Southern Oscillation. Journal of Climate 25 (2012):6108–6122. doi:http://dx.doi.org/10.1175/JCLI-D-11-00647.1
  62. ^ a b Neumann, Charles J. "Worldwide Tropical Cyclone Tracks 1979–88". Global Guide to Tropical Cyclone Forecasting. Bureau of Meteorology. Retrieved December 12, 2006. 
  63. ^ Henderson-Sellers, H. Zhang, G. Berz, K. Emanuel, William Gray, Christopher Landsea, Greg Holland, J. Lighthill, S-L. Shieh, P. Webster, and K. McGuffie. (October 8, 2002). "Tropical Cyclones and Global Climate Change: A Post-IPCC Assessment". National Oceanic and Atmospheric Administration. Retrieved May 7, 2009. 
  64. ^ "Monthly Global Tropical Cyclone Summary, December 2001". Gary Padgett. Australian Severe Weather Index. Retrieved May 6, 2009. 
  65. ^ "Annual Tropical Cyclone Report 2004". Joint Typhoon Warning Center. 2006. Retrieved May 6, 2009. 
  66. ^ Holland, Greg J (February 1983). "Tropical cyclone motion: Environmental interaction plus a beta effect". Journal of the Atmospheric Sciences 40 (2): 328–342. Retrieved Aug 26, 2014. 
  67. ^ a b Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: What determines the movement of tropical cyclones?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  68. ^ DeCaria, Alex (2005). "Lesson 5 – Tropical Cyclones: Climatology.". ESCI 344 – Tropical Meteorology. Millersville University. Archived from the original on May 7, 2008. Retrieved February 22, 2008. 
  69. ^ "Fujiwhara effect describes a stormy waltz". USA Today. November 9, 2007. Retrieved February 21, 2008. 
  70. ^ "Section 2: Tropical Cyclone Motion Terminology". United States Naval Research Laboratory. April 10, 2007. Retrieved May 7, 2009. 
  71. ^ Powell, Jeff, et al. (May 2007). "Hurricane Ioke: 20–27 August 2006". 2006 Tropical Cyclones Central North Pacific. Central Pacific Hurricane Center. Retrieved June 9, 2007. 
  72. ^ "Subject : C2) Doesn't the friction over land kill tropical cyclones?". National Hurricane Center. National Oceanic and Atmospheric Administration. February 25, 2008. Retrieved May 7, 2009. 
  73. ^ "Tropical Cyclones Affecting Inland Pilbara towns.". Bureau of Meteorology. Retrieved May 7, 2009. 
  74. ^ Yuh-Lang Lin, S. Chiao, J. A. Thurman, D. B. Ensley, and J. J. Charney. Some Common Ingredients for heavy Orographic Rainfall and their Potential Application for Prediction. Retrieved on April 26, 2007.
  75. ^ a b National Hurricane Center (1998). "Hurricane Mitch Tropical Cyclone Report". Retrieved April 20, 2006. 
  76. ^ Shay, Lynn K., Russell L. Elsberry and Peter G. Black (May 1989). "Vertical Structure of the Ocean Current Response to a Hurricane" (PDF). Journal of Physical Oceanography 19 (5): 649. Bibcode:1989JPO....19..649S. doi:10.1175/1520-0485(1989)019<0649:VSOTOC>2.0.CO;2. ISSN 1520-0485. Retrieved December 12, 2006. 
  77. ^ Edwards, Jonathan. "Tropical Cyclone Formation". HurricaneZone.net. Archived from the original on February 21, 2007. Retrieved November 30, 2006. 
  78. ^ a b Chih-Pei Chang (2004). East Asian Monsoon. World Scientific. ISBN 981-238-769-2. OCLC 61353183. 
  79. ^ United States Naval Research Laboratory (September 23, 1999). "Tropical Cyclone Intensity Terminology". Tropical Cyclone Forecasters' Reference Guide. Retrieved November 30, 2006. 
  80. ^ Rappaport, Edward N. (November 2, 2000). "Preliminary Report: Hurricane Iris: 22–4 August September 1995". National Hurricane Center. Retrieved November 29, 2006. 
  81. ^ Jon Hamilton (September 5, 2008). "African Dust Linked To Hurricane Strength". All Things Considered. National Public Radio. Retrieved May 7, 2009. 
  82. ^ "Project Stormfury". Hurricane Research Division. National Oceanic and Atmospheric Administration. February 7, 2009. Retrieved May 7, 2009. 
  83. ^ H. E. Willoughby, D. P. Jorgensen, R. A. Black, and S. L. Rosenthal. (May 23, 2000). "Project Stormfury: A Scientific Chronicle 1962–1983.". National Oceanic and Atmospheric Administration. American Meteorological Society. Retrieved May 7, 2009. 
  84. ^ Whipple, Addison (1982). Storm. Alexandria, VA: Time Life Books. p. 151. ISBN 0-8094-4312-0. 
  85. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: Why don't we try to destroy tropical cyclones by seeding them with silver torches iodide?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  86. ^ a b Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: Why don't we try to destroy tropical cyclones by cooling the surface waters with icebergs or deep ocean water?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  87. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: Why don't we try to destroy tropical cyclones by placing a substance on the ocean surface?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  88. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: Why don't we try to destroy tropical cyclones by nuking them?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  89. ^ Scotti, R. A. (2003). Sudden Sea: The Great Hurricane of 1938 (1st ed.). Little, Brown, and Company. p. 47. ISBN 0-316-73911-1. OCLC 51861977. 
  90. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: Why do not we try to destroy tropical cyclones by (fill in the blank)?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  91. ^ David Roth and Hugh Cobb (2001). "Eighteenth Century Virginia Hurricanes". NOAA. Retrieved February 24, 2007. 
  92. ^ James M. Shultz, Jill Russell and Zelde Espinel (2005). "Epidemiology of Tropical Cyclones: The Dynamics of Disaster, Disease, and Development". Oxford Journal. Retrieved February 24, 2007. 
  93. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: Are TC tornadoes weaker than midlatitude tornadoes?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  94. ^ a b c Shultz, James M., Jill Russell and Zelde Espinel (July 2005). "Epidemiology of Tropical Cyclones: The Dynamics of Disaster, Disease, and Development". Epidemiologic Reviews 27 (1): 21–25. doi:10.1093/epirev/mxi011. PMID 15958424. Retrieved December 14, 2006. 
  95. ^ Staff Writer (August 30, 2005). "Hurricane Katrina Situation Report #11" (PDF). Office of Electricity Delivery and Energy Reliability (OE) United States Department of Energy. Retrieved February 24, 2007. 
  96. ^ Burroughs, William James (2007). Climate change : a multidisciplinary approach (2nd ed.). Cambridge: Cambridge University Press. ISBN 978-0-521-87015-3. 
  97. ^ National Oceanic and Atmospheric Administration. 2005 Tropical Eastern North Pacific Hurricane Outlook. Retrieved on May 2, 2006.
  98. ^ National Weather Service (October 19, 2005). "Tropical Cyclone Introduction". JetStream — An Online School for Weather. National Oceanic & Atmospheric Administration. Retrieved September 7, 2010. 
  99. ^ Emanuel, Kerry (July 2001). "Contribution of tropical cyclones to meridional heat transport by the oceans". Journal of Geophysical Research 106 (D14): 14771–14781. Bibcode:2001JGR...10614771E. doi:10.1029/2000JD900641. 
  100. ^ Christopherson, Robert W. (1992). Geosystems: An Introduction to Physical Geography. New York: Macmillan Publishing Company. pp. 222–224. ISBN 0-02-322443-6. 
  101. ^ Doyle, Thomas (2005). "Wind damage and Salinity Effects of Hurricanes Katrina and Rita on Coastal Baldcypress Forests of Louisiana". Retrieved 13 Feb 2014. 
  102. ^ Cappielo, Dina (2005). "Spills from hurricanes stain coast With gallery - Houston Chronicle". Chron. Retrieved 12 Feb 2014. 
  103. ^ Florida Coastal Monitoring Program. "Project Overview". University of Florida. Archived from the original on May 3, 2006. Retrieved March 30, 2006. 
  104. ^ "Observations". Central Pacific Hurricane Center. December 9, 2006. Retrieved May 7, 2009. 
  105. ^ 403rd Wing. "The Hurricane Hunters". 53rd Weather Reconnaissance Squadron. Retrieved March 30, 2006. 
  106. ^ Lee, Christopher. "Drone, Sensors May Open Path Into Eye of Storm". The Washington Post. Retrieved February 22, 2008. 
  107. ^ "Influences on Tropical Cyclone Motion". United States Navy. Retrieved April 10, 2007. 
  108. ^ National Hurricane Center (May 22, 2006). "Annual average model track errors for Atlantic basin tropical cyclones for the period 1994–2005, for a homogeneous selection of "early" models". National Hurricane Center Forecast Verification. National Oceanic and Atmospheric Administration. Retrieved November 30, 2006. 
  109. ^ National Hurricane Center (May 22, 2006). "Annual average official track errors for Atlantic basin tropical cyclones for the period 1989–2005, with least-squares trend lines superimposed". National Hurricane Center Forecast Verification. National Oceanic and Atmospheric Administration. Retrieved November 30, 2006. 
  110. ^ Central Pacific Hurricane Center (2004). Hurricane John Preliminary Report (Report). National Oceanic and Atmospheric Administration. http://www.prh.noaa.gov/cphc/summaries/1994.php#John. Retrieved March 23, 2007.
  111. ^ Bouchard, R. H. (April 1990). "A Climatology of Very Intense Typhoons: Or Where Have All the Super Typhoons Gone?" (PPT). Archived from the original on March 16, 2007. Retrieved December 5, 2006. 
  112. ^ a b c National Weather Service (September 2006). "Hurricanes ... Unleashing Nature's Fury: A Preparedness Guide" (PDF). National Oceanic and Atmospheric Administration. Archived from the original on February 26, 2008. Retrieved December 2, 2006. 
  113. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: What are the upcoming tropical cyclone names?". National Oceanic and Atmospheric Administration. Retrieved December 11, 2006. 
  114. ^ "Storm Damge Center". Retrieved 2014-11-06. 
  115. ^ a b Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: Which is the most intense tropical cyclone on record?". NOAA. Retrieved July 25, 2006. 
  116. ^ National Hurricane Center. Subject: A1) What is a hurricane, typhoon, or tropical cyclone? Retrieved on 2008-02-25.
  117. ^ Bureau of Meteorology. Global Guide to Tropical Cyclone Forecasting Retrieved on 2008-02-25.
  118. ^ RA V Tropical Cyclone Committee (December 12, 2012) (PDF). Tropical Cyclone Operational Plan for the South-East Indian Ocean and the Southern Pacific Ocean 2012 (Report). World Meteorological Organization. http://www.wmo.int/pages/prog/www/tcp/documents/TCP24_RAVOpPlan_2012.pdf. Retrieved December 14, 2012.
  119. ^ "Typhoon". The American Heritage Dictionary of the English Language (4th ed.). Dictionary.com. 2004. Retrieved December 14, 2006. 
  120. ^ "Disaster Controlled Vocabulary (VDC)" (PDF). Centro Regional de Información sobre Desastres. Archived from the original on February 26, 2008. Retrieved January 24, 2008. 
  121. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: What is the origin of the word "hurricane"?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  122. ^ a b Read, Kay Almere; Jason González (2000). Handbook of Mesoamerican Mythology. Oxford: ABC-CLIO. p. 200. ISBN 1-85109-340-0. OCLC 43879188. 
  123. ^ "Worldwide Tropical Cyclone Names.". National Hurricane Center. National Oceanic and Atmospheric Administration. 2009. Retrieved May 7, 2009. 
  124. ^ "Reason to Name Hurricanes". Atlantic Oceanographic and Meteorological Laboratory. National Oceanographic and Atmospheric Administration. Retrieved November 7, 2012. 
  125. ^ "Hurricanes named after females more deadly". Australian Geographic. 18 November 2014. Retrieved 18 November 2014. 
  126. ^ a b Chris Landsea (1993). "Which tropical cyclones have caused the most deaths and most damage?". Hurricane Research Division. Retrieved February 23, 2007. 
  127. ^ Lawson (November 2, 1999). "South Asia: A history of destruction". British Broadcasting Corporation. Retrieved February 23, 2007. 
  128. ^ Frank, Neil L. and S. A. Husain (June 1971). "The Deadliest Tropical Cyclone in History" (PDF). Bulletin of the American Meteorological Society 52 (6): 438–445. Bibcode:1971BAMS...52..438F. doi:10.1175/1520-0477(1971)052<0438:TDTCIH>2.0.CO;2. ISSN 1520-0477. Retrieved December 14, 2006. 
  129. ^ Linda J. Anderson-Berry. Fifth International Workshop on Tropycal Cyclones: Topic 5.1: Societal Impacts of Tropical Cyclones. Retrieved on February 26, 2008.
  130. ^ National Hurricane Center (April 22, 1997). "The Deadliest Atlantic Tropical Cyclones, 1492–1996". National Oceanic and Atmospheric Administration. Retrieved March 31, 2006. 
  131. ^ Joint Typhoon Warning Center. "Typhoon Thelma (27W)" (PDF). 1991 Annual Tropical Cyclone Report. Retrieved March 31, 2006. 
  132. ^ Gunther, E. B., R.L. Cross, and R.A. Wagoner (May 1983). "Eastern North Pacific Tropical Cyclones of 1982" (PDF). Monthly Weather Review 111 (5): 1080. Bibcode:1983MWRv..111.1080G. doi:10.1175/1520-0493(1983)111<1080:ENPTCO>2.0.CO;2. ISSN 1520-0493. Retrieved March 31, 2006. 
  133. ^ a b Earth Policy Institute (2006). "Hurricane Damages Sour to New Levels". United States Department of Commerce. Retrieved February 23, 2007. [dead link]
  134. ^ a b Knabb, Richard D., Jamie R. Rhome and Daniel P. Brown (December 20, 2005). "Tropical Cyclone Report: Hurricane Katrina: 23–30 August 2005" (PDF). National Hurricane Center. Retrieved May 30, 2006. 
  135. ^ National Hurricane Center. Galveston Hurricane 1900. Retrieved on February 24, 2008.
  136. ^ Central Pacific Hurricane Center. "Hurricane Iniki Natural Disaster Survey Report". National Oceanic and Atmospheric Administration. Retrieved March 31, 2006. 
  137. ^ Lawrence, Miles B. (November 7, 1997). "Preliminary Report: Hurricane Pauline: 5–10 October 1997". National Hurricane Center. Retrieved March 31, 2006. 
  138. ^ Franklin, James L. (December 26, 2002). "Tropical Cyclone Report: Hurricane Kenna: 22–26 October 2002". National Hurricane Center. Retrieved March 31, 2006. 
  139. ^ World Food Programme (2004). "WFP Assists Cyclone And Flood Victims in Madagascar". Retrieved February 24, 2007. 
  140. ^ "20,254 Flights Canceled Due to Hurricane Sandy". The San Francisco Chronicle. November 3, 2012. Retrieved December 25, 2012. 
  141. ^ "Almost 20,000 flights canceled due to Sandy". The Wall Street Journal. October 31, 2012. Retrieved December 25, 2012. 
  142. ^ "Analyst puts Hurricane Sandy losses at close to $200 million for airlines". Aviation Blog. Dallas News.com. Retrieved December 25, 2012. 
  143. ^ Keller, Josh; Goldstein, Joseph; Goodman, J. David; Silva, Daniella (November 17, 2012). "Mapping Hurricane Sandy's Deadly Toll". The New York Times. Retrieved December 25, 2012. 
  144. ^ "Who died during Hurricane Sandy, and why?". EarthSky.org. Retrieved December 25, 2012. 
  145. ^ "Disaster Update". Safeguard Properties. Retrieved December 25, 2012. 
  146. ^ "Hurricane Sandy wreaked havoc - total cost of damage over $71 billion". Irish Central. Retrieved December 25, 2012. 
  147. ^ Fontevecchia, Agustino. "Despite $50B In Damages, Hurricane Sandy Will Be Good For The Economy, Goldman Says". Forbes. Retrieved December 25, 2012. 
  148. ^ George M. Dunnavan & John W. Dierks (1980). "An Analysis of Super Typhoon Tip (October 1979)" (PDF). Joint Typhoon Warning Center. Retrieved January 24, 2007. 
  149. ^ Ferrell, Jesse (October 26, 1998). "Hurricane Mitch". Weathermatrix.net. Archived from the original on September 28, 2007. Retrieved March 30, 2006. 
  150. ^ Houston, Sam, Greg Forbes and Arthur Chiu (August 17, 1998). "Super Typhoon Paka's (1997) Surface Winds Over Guam". National Weather Service. Retrieved March 30, 2006. 
  151. ^ Dorst, Neal; Hurricane Research Division (May 29, 2009). "Frequently Asked Questions: Subject: E5) Which are the largest and smallest tropical cyclones on record?". National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory. Retrieved June 12, 2013. 
  152. ^ Dorst, Neal; Hurricane Research Division (January 26, 2010). "Subject: E6) Frequently Asked Questions: Which tropical cyclone lasted the longest?". National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory. Retrieved June 12, 2013. 
  153. ^ a b Dorst, Neal; Delgado, Sandy; Hurricane Research Division (May 20, 2011). "Frequently Asked Questions: Subject: E7) What is the farthest a tropical cyclone has travelled?". National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory. Retrieved June 12, 2013. 
  154. ^ Joint Typhoon Warning Center (2006). "3.3 JTWC Forecasting Philosophies". United States Navy. Retrieved February 11, 2007. 
  155. ^ a b M. C. Wu, W. L. Chang, and W. M. Leung (2003). "Impacts of El Niño-Southern Oscillation Events on Tropical Cyclone Landfalling Activity in the Western North Pacific". Journal of Climate 17 (6): 1419–1428. Bibcode:2004JCli...17.1419W. doi:10.1175/1520-0442(2004)017<1419:IOENOE>2.0.CO;2. ISSN 1520-0442. Retrieved February 11, 2007. 
  156. ^ Pacific ENSO Applications Climate Center. "Pacific ENSO Update: 4th Quarter, 2006. Vol. 12 No. 4". Retrieved March 19, 2008. 
  157. ^ Edward N. Rappaport (September 1999). "Atlantic Hurricane Season of 1997". Monthly Weather Review 127 (9): 2012. Bibcode:1999MWRv..127.2012R. doi:10.1175/1520-0493(1999)127<2012:AHSO>2.0.CO;2. ISSN 1520-0493. Retrieved July 18, 2009. 
  158. ^ Emanuel, Kerry (January 2006). "Anthropogenic Effects on Tropical Cyclone Activity". Retrieved March 30, 2006. 
  159. ^ "Summary Statement on Tropical Cyclones and Climate Change" (PDF) (Press release). World Meteorological Organization. December 4, 2006. Retrieved May 7, 2009. 
  160. ^ a b c Pielke, Roger A., Jr. et al. (2008). "Normalized Hurricane Damage in the United States: 1900–2005" (PDF). Natural Hazards Review 9 (1): 29–42. doi:10.1061/(ASCE)1527-6988(2008)9:1(29). Retrieved May 7, 2009. 
  161. ^ a b Neumann, Charles J. "1.3: A Global Climatology". Global Guide to Tropical Cyclone Forecasting. Bureau of Meteorology. Retrieved November 30, 2006. 
  162. ^ Malmgren, J.; Winter, A.; Malmgren, B. A. (2005). "Reconstruction of Major Hurricane Activity". Eos Trans. AGU 86 (52, Fall Meet. Suppl.): Abstract PP21C–1597. Bibcode:2005AGUFMPP21C1597N. Retrieved May 7, 2009. 
  163. ^ Risk Management Solutions (March 2006). "U.S. and Caribbean Hurricane Activity Rates." (PDF). Retrieved November 30, 2006. 
  164. ^ Center for Climate Systems Research. "Hurricanes, Sea Level Rise, and New York City". Columbia University. Archived from the original on January 2, 2007. Retrieved November 29, 2006. 
  165. ^ Liu, Kam-biu (1999). "Millennial-scale variability in catastrophic hurricane landfalls along the Gulf of Mexico coast". 23rd Conference on Hurricanes and Tropical Meteorology. Dallas, Texas, United States of America: American Meteorological Society. pp. 374–377. 
  166. ^ a b Liu, Kam-biu; Fearn, Miriam L. (2000). "Reconstruction of Prehistoric Landfall Frequencies of Catastrophic Hurricanes in Northwestern Florida from Lake Sediment Records". Quaternary Research 54 (2): 238–245. Bibcode:2000QuRes..54..238L. doi:10.1006/qres.2000.2166. 
  167. ^ Elsner, James B.; Liu, Kam-biu; Kocher, Bethany (2000). "Spatial Variations in Major U.S. Hurricane Activity: Statistics and a Physical Mechanism". Journal of Climate 13 (13): 2293–2305. Bibcode:2000JCli...13.2293E. doi:10.1175/1520-0442(2000)013<2293:SVIMUS>2.0.CO;2. ISSN 1520-0442. 
  168. ^ Higuera-Gundy, Antonia et al. (1999). "A 10,300 14C yr Record of Climate and Vegetation Change from Haiti". Quaternary Research 52 (2): 159–170. Bibcode:1999QuRes..52..159H. doi:10.1006/qres.1999.2062. 
  169. ^ Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (Eds.) (2012). IPCC , 2012: Summary for Policymakers. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. Cambridge University Press. p. 9. 
  170. ^ Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (Eds.) (2012). IPCC , 2012: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. Cambridge University Press. pp. 268–269. 
  171. ^ "Geophysical Fluid Dynamics Laboratory - Global Warming and Hurricanes". Retrieved October 1, 2014. 
  172. ^ http://www.epw.senate.gov/public/index.cfm?FuseAction=Files.View&FileStore_id=a6df9665-e8c8-4b0f-a550-07669df48b15
  173. ^ Geophysical Fluid Dynamics Laboratory. "Global Warming and Hurricanes". National Oceanic and Atmospheric Administration. Retrieved November 29, 2006. 
  174. ^ Emanuel, Kerry. "Downscaling CMIP5 climate models shows increadaed tropical cyclone activity over the 21st century". Downscaling CMIP5 clinmate models shows increadaed tropical cyclone activity over the 21st century. Retrieved March 24, 2014. 
  175. ^ Blake, Eric S.; Landsea, Christopher W.; Gibney, Ethan J. (2011). "The Deadliest, Costliest, and the most intense United States Tropical Cyclones from 1851 to 2010 (and other frequently requested hurricane facts)". NOAA Technical Memorandum NWS NHC-6. 
  176. ^ a b c "Increasing destructiveness of tropical cyclones over the past 30 years" (PDF). Nature 436 (7051): 686–688. 2005. Bibcode:2005Natur.436..686E. doi:10.1038/nature03906. PMID 16056221. Retrieved March 20, 2006. 
  177. ^ Emanuel, Kerry; Sundararajan, Ragoth; Williams, John (March 2008). "Hurricanes and Global Warming: Results from Downscaling IPCC AR4 Simulations". Bulletin of the American Meteorological Society 89 (3): 347–367. Bibcode:2008BAMS...89..347E. doi:10.1175/BAMS-89-3-347. 
  178. ^ Berger, Eric (April 12, 2008). "Hurricane expert reconsiders global warming's impact". Houston Chronicle. Retrieved July 31, 2010. 
  179. ^ Webster, P. J.; Holland G.J.; Curry J.A.; Chang H.R. (September 16, 2005). "Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment" (PDF). Science 309 (5742): 1844–1846. Bibcode:2005Sci...309.1844W. doi:10.1126/science.1116448. PMID 16166514. Retrieved September 2, 2012. 
  180. ^ Knutson, Thomas R.; Tuleya, Robert E. (2004). "Impact of CO2-Induced Warming on Simulated Hurricane Intensity and Precipitation: Sensitivity to the Choice of Climate Model and Convective Parameterization". Journal of Climate 17 (18): 3477–3494. Bibcode:2004JCli...17.3477K. doi:10.1175/1520-0442(2004)017<3477:IOCWOS>2.0.CO;2. ISSN 1520-0442. 
  181. ^ Pielke, R. A. Jr (2005). "Meteorology: Are there trends in hurricane destruction?". Nature 438 (7071): E11. Bibcode:2005Natur.438E..11P. doi:10.1038/nature04426. PMID 16371954. 
  182. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: How do tropical cyclones form?". National Oceanic and Atmospheric Administration. Retrieved August 2, 2012. 
  183. ^ a b Stefan Rahmstorf, Michael E. Mann, Rasmus Benestad, Gavin Schmidt and William Connolley (September 2, 2005). "Hurricanes and Global Warming — Is There a Connection?". RealClimate. Retrieved March 20, 2006. 
  184. ^ Richard Alley, et al. (2007). "Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change". United Nations. Retrieved February 23, 2007. 
  185. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: What may happen with tropical cyclone activity due to global warming?". NOAA. Retrieved June 2, 2007. 
  186. ^ American Meteorological Society (February 1, 2007). "Climate Change: An Information Statement of the American Meteorological Society" (PDF). Bulletin of the American Meteorological Society 88 (1): 5. Retrieved June 3, 2007. 
  187. ^ a b World Meteorological Organization (December 11, 2006). "Statement on Tropical Cyclones and Climate Change" (PDF). p. 6. Retrieved June 2, 2007. 
  188. ^ Hurricanes are getting fiercer Nature, Retrieved on September 4, 2008.
  189. ^ Warmer Seas Linked to Strengthening Hurricanes: Study Fuels Global Warming Debate Newswise, Retrieved on September 4, 2008.
  190. ^ Mark A. Lander, N. Davidson, H. Rosendal, J. Knaff, and R. Edson, J. Evans, R. Hart. (August 3, 2003). "Fifth International Workshop on Tropical Cyclones". World Meteorological Organization. Retrieved May 6, 2009. 
  191. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: What is an extra-tropical cyclone?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  192. ^ "Lesson 14: Background: Synoptic Scale". University of Wisconsin–Madison. February 25, 2008. Retrieved May 6, 2009. 
  193. ^ "An Overview of Coastal Land Loss: With Emphasis on the Southeastern United States.". United States Geological Survey. 2008. Retrieved May 6, 2009. 
  194. ^ Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. "Frequently Asked Questions: What is a sub-tropical cyclone?". National Oceanic and Atmospheric Administration. Retrieved July 25, 2006. 
  195. ^ Padgett, Gary (2001). "Monthly Global Tropical Cyclone Summary for December 2000". Retrieved March 31, 2006. 
  196. ^ a b c Dorst, Neal; Hurricane Research Division (June 1, 2013). "Subject: J4) What fictional books, plays, poems, and movies have been written involving tropical cyclones?". Tropical Cyclone Frequently Asked Questions:. National Oceanic and Atmospheric Administration. Retrieved March 30, 2013. 
  197. ^ Dorst, Neal; Hurricane Research Division (October 23, 2012). "They Called the Wind Mahina: The History of Naming Cyclones" (PPTX). National Oceanic and Atmospheric Administration. p. Slides 8–72. 
  198. ^ McCown, Sean (December 13, 2004). "Unnamed Hurricane 1991". Satellite Events Art Gallery: Hurricanes. National Climatic Data Center. Retrieved February 4, 2007. 
  199. ^ "Hurricane Neddy – Episode Overview". Yahoo! TV. Retrieved February 26, 2008. 
  200. ^ "Family Guy: One if by Clam, Two if by Sea – Summary". starpulse.com. Retrieved February 26, 2008. 
  201. ^ "Dawson's Creek – Hurricane". "Yahoo! TV. Retrieved February 25, 2008. 
  202. ^ TheNewsGuy(Mike). "The Checks (Seinfeld Episode Script)". Seinfeldscripts.com. Retrieved February 25, 2007. 
  203. ^ "CSI: Miami Episodes – Episode Detail: Hurricane Anthony". TV Guide. Retrieved February 25, 2008. 
  204. ^ "The Day After Tomorrow Movie Synopsis". Tribute.ca. Retrieved February 26, 2008. 
  205. ^ "The Day After Tomorrow (2004)". The New York Times. Retrieved February 26, 2008. 

External links[edit]

Regional Specialized Meteorological Centers

Tropical Cyclone Warning Centers

Reference