Hurricane is a tropical cyclone in the northern Atlantic Ocean (including the Caribbean and the Gulf of Mexico ) as well as in the North Pacific east of 180 ° longitude and in the South Pacific east of 160 ° East (i.e. east of the international date line ). This must reach at least a hurricane force, i.e. wind force 12 on the Beaufort scale (this corresponds to more than 64 knots or 118 km / h). Hurricanes usually occur between May and December, most of them between July and September. The official hurricane season in the Atlantic Ocean and the central North Pacific lasts from June 1st to November 30th, in the eastern North Pacific it starts on May 15th.
Origin of name
The name "hurricane" probably goes back to the language of the Taíno , the indigenous people of the Greater Antilles . This is evident from the first written evidence of the word. It can be found in the first of the eight “decades” (published 1511/1516) of the work De Orbe Novo , written in Latin by Petrus Martyr von Anghieras . Anglerius reported here by a storm in 1495 the Spanish stronghold of La Isabela devastated, and remarks on this occasion that of such forces of nature that the Greeks as Typhon (see. Typhoon were known), by the natives of Hispaniola furacanes would called ( , has aeris procellas uti Graeci typhones, furacanes isti appellant ' ). Obvious, but not proven, is the often-read assumption that there is a connection with Huracán or Hun-r-akan , the name of a Maya deity of the Central American mainland who is responsible for severe storms, but not linguistically with the Taíno related and also culturally very different.
Via Spanish ( huracán , first attested by Gonzalo Fernández de Oviedo in 1526 ), the word found its way into Portuguese in the 16th century ( furacão , the initial / f / is explained as a Latinized hypercorrection ) and into French (in the obsolete form huracan for the first time in 1553 , proven in today's spelling ouragan 1640), in the 17th century then into Dutch and from there into German - albeit initially in the form of " hurricane ", which in today's parlance does not mean tropical winds, but the Atlantic storms, especially in autumn and winters sweep across Europe more often. The etymological duplicate "Hurricane" as a term for tropical storms in distant regions, however, only became common in German as a foreign or loan word towards the middle of the 19th century and clearly shows the influence of English ( hurricane , the spelling is probably explained by a folk etymological association with hurry , "hurry, speedy"; in the 17th century, for example with Sir Walter Raleigh , there are also various forms such as hurlecan , which are obviously linked to the verb hurl "swirl").
Spelling and pronunciation
The online Duden lists both the German [ ˈhʊrikan ] and the English pronunciation [ ˈhʌrɪkən ] for the German spelling Hurrikan , with the English being mentioned first. In German, the majority is hurricanes , whereas in English it is hurricane . The printed Duden from 2005 names the pronunciation [ ˈharikən ], which appears next to [ ˈhʊrika (ː) n ] in Pons' dictionaries.
Differentiated from cyclone and typhoon
As a "hurricane" today only tropical storms are generally referred to, which affect the seas and coasts east and west of the American double continent.
Storms that resemble tropical cyclones are also occasionally observed in the Mediterranean . Such a storm is also called Medicane ( suitcase word from English Mediterranean Sea (Mediterranean Sea) and hurricane ).
|1||Great hurricane of 1780||1780||22,000+|
|3||Galveston Hurricane 1900||1900||6,000-12,000|
|5||San Zenon Hurricane||1930||2,000-8,000|
|10||San Ciriaco hurricane||1899||3,064-3,433 +|
|Ranking according to the highest assumed number of victims.|
The highest material damage to date was caused by Hurricane Katrina in August 2005 at around $ 81 billion . Katrina moved with winds of 250 to 300 km / h over Florida , Louisiana - especially over the New Orleans metropolitan area -, Mississippi , Alabama and Tennessee and claimed over a thousand lives.
The greatest number of deaths from an Atlantic hurricane, namely around 22,000 lives, was caused by the Great Hurricane of 1780 .
The strongest hurricane recorded to date in the Atlantic Ocean was Hurricane Wilma . With a core pressure of 882 hPa , the lowest air pressure ever measured on the Atlantic prevailed in the center of Wilma. In addition, from October 18 to 19, 2005, Wilma intensified from a tropical storm with wind speeds of less than 113 km / h to a category 5 hurricane (over 282 km / h) faster than any other observed hurricane .
Hurricane Patricia was both the strongest hurricane in the North Pacific and the strongest hurricane ever recorded in the world . Patricia's core pressure was 872 hPa, which is a record in the western hemisphere . Only in Taifun Tip could an even lower air pressure of 870 hPa be measured. Hurricane Patricia also holds the record of 345 km / h (1 minute) for the highest sustained wind speeds ever recorded in a tropical cyclone. Although the same mean wind was calculated in Typhoon Nancy in 1961 , the measurement methods used at that time are not considered reliable today. Another record by Patricia is in its rapid intensification. From October 22nd to 23rd, 2015, the one-minute mean wind speed of the hurricane increased from 138 km / h to 335 km / h and thus by 197 km / h within 24 hours.
If a hurricane even reaches the frontal zone of the middle latitudes, it has already lost a larger part of its damage energy and is then usually downgraded to an extra-tropical low pressure system ( extratropical transition) or to a lower category. Such a weather system is still able to bring heavy rains to Europe .
The characteristics of an upcoming Atlantic hurricane season are forecast every year by the National Oceanic and Atmospheric Administration (NOAA) and separately by the Tropical Risk Consortium (TSR) and a team at Colorado State University using a weather forecast.
Formation and life cycle
Hurricanes generally occur in the trade wind zone over the water of the Atlantic or eastern Pacific at a water temperature of over 26.5 ° C. If a constant temperature gradient at high altitudes exceeds a certain level, a tropical cyclone can form. The water evaporates in large quantities and rises by convection . Large clouds form due to condensation .
This condensation of huge water masses releases enormous amounts of energy ( latent heat ). The air inside the clouds is heated up, expands and then rises even further with the residual moisture that has not yet rained out. A negative pressure is created above the warm sea surface and air with a high proportion of water vapor flows in from the surroundings. This creates a zone of very high air pressure above the hurricane clouds, out of which the air is redistributed in an opposing vortex ( anticyclones ).
However, the area covered by a hurricane is far too large for a single, closed air parcel to form and rise as a whole. Typical of all tropical cyclones is the formation of spiral rain bands, in which thermal updrafts prevail, and zones in between, in which somewhat cooler and drier air sinks again - without rain. After-flowing moist air rises in the rain bands and constantly supplies water and energy. The air masses flowing in on the ground are set in rotation by the Coriolis force , creating a large-area vortex .
If a hurricane comes close to land, its near-ground supply flows also shift partly over land, which means that considerably drier air enters the system and reduces the energy supply. If a hurricane moves across land, its water and energy supply largely dries up: it gradually loses its power and initially becomes a (weaker) tropical storm , only to be lost as a tropical low.
Important prerequisites for tropical storm formation are therefore:
- The sea must have a surface temperature of at least 26.5 ° C and the air must have a uniform temperature decrease (“gradient”) towards high altitudes. If the temperature drops very sharply, which favors the rise of the warm, humid air, lower water temperatures may be sufficient (see also Hurricane Vince .)
- The affected area of uniform conditions must be extensive so that the moving cyclone can build up over a longer period of time due to the formation of water vapor and collect enough energy up to the strength of a hurricane.
- The distance from the equator must be large enough (at least 5 degrees of latitude or 550 km), since only then is the Coriolis force strong enough to give the incoming air masses the typical rotation.
- The sea must be at least 50 meters deep, otherwise there will not be enough heat per surface.
- There must be no large vertical wind shear , which means that in order for a hurricane to occur, the wind at high altitude has to blow with similar strength and from the same direction as the wind from the ground. If this is not the case, the ascending winds are tilted and the chimney collapses.
- The storm needs a nucleus from which it can build, for example an extra-tropical low .
The meteorological and thermodynamic function of a hurricane is that it absorbs very large amounts of heat from the surface of the tropical oceans and transports it first upwards and then towards the poles. at the top the energy is then gradually radiated into space.
The intensity of tropical cyclones follows empirical knowledge of the surface temperature of the sea. It should be noted that these temperatures vary over a period of several decades for reasons that are not yet known. In the North Atlantic, the Atlantic Multidecadal Oscillation (AMO) alternates between "warm" and "cold" every 20 to 30 years , while in the Northeast Pacific the Pacific Decadal Oscillation changes every 20 to 30 years. In the North Atlantic in particular, a trend can be seen that with “warm” AMO there are significantly more intense hurricane seasons than with “cold” ones. Seven of the ten most intense hurricane seasons (since measurements began in 1850) occurred in the penultimate two AMO warm phases from ~ 1850 to ~ 1900 and ~ 1925 to ~ 1965. In the subsequent cold phase, which lasted until the early 1990s , however, there were only comparatively mild hurricane seasons. The AMO has been in a warm phase again since around 1995, which is why the hurricane intensity has increased significantly again. Researchers at the National Oceanic and Atmospheric Administration assume that this phase of increased hurricane intensity in the Atlantic Ocean will last for another 10 to 40 years. The occurrence of the El Niño phenomenon increases the likelihood of wind shear on the east coast of the United States , so El Niño years coincide here with a reduced hurricane likelihood (the opposite is the case for the west coast ).
Places of origin
Hurricanes generally arise in the trade wind zone , in the Atlantic Ocean mostly southwest of Cape Verde , in the area of the Caribbean Sea , the West Indies and the Gulf of Mexico, from minor disturbances in the trade current that cross the Atlantic from just south of the Sahara desert . This region, where most of the hurricanes occur, is also called Hurricane Alley .
With Hurricane Vince a tropical cyclone off the coast of southern Europe and North Africa in the eastern Atlantic was formed on October 9, 2005 was the first since "Spain Hurricane" from 1,842th Vince formed between the Azores and the Canaries , but weakened to a storm low before reaching mainland Europe.
The tropical storm Delta, Hurricane Epsilon, as well as the tropical storm Zeta also originated in the eastern Atlantic in 2005, so that with Vince and Delta, two hurricanes hit the coasts of Europe for the first time in one year.
|category||Wind in kn||Wind in km / h||Tidal wave when hitting land (in m)||Core pressure in hPa|
|1 (weak)||64-82||118-152||1.2-1.6||over 980|
|4 (very strong)||114-135||211-250||3.9-5.5||920-944|
|5 (devastating)||from 136||from 252||over 5.5||below 920|
The destructive power of a hurricane increases roughly with the third power of the wind speed.
The listed wind speed values are based on a 1-minute average value as used in the USA. The conversion factor for the corresponding 10-minute averages is 0.88.
The draft speed of the hurricane, which is measured with the movement of the eye towards the ground, must be distinguished from the wind speed. The resulting wind speed above ground results from the movement of the center (pulling speed) and the revolving rotation movement of the vortex. The rotation speed and the pulling speed have the consequence that stronger wind speeds are measured on the right side of a hurricane than on the left side of the eye, which counteracts the pulling direction. This is always the case, because hurricanes always turn to the left in the northern hemisphere due to the Coriolis force .
In seafaring, the left side is therefore also referred to as the navigable quarter (more rarely: navigable semicircle). The rotation speed also increases with increasing proximity to the center and is greatest in the area of the eyewall around the almost windless eye .
A hurricane with a diameter of up to 100 km can reach wind speeds of over 200 km / h; in the particularly endangered zones to the right of the direction of movement of a devastating category 5 hurricane, 300 km / h are exceeded.
Course and behavior
Even if Atlantic hurricanes mostly move west to north-west shortly after their formation and often turn north to north-east between the 20th and 25th parallel, this typical behavior is neither mandatory nor to be expected safely.
From quasi stationary hurricanes, which weakened themselves by bringing cooler sea water to the surface, to prancing, lurching and loop-shaped courses over the ground, everything has already been observed. Cyclones moving eastwards and unexpected short-term changes of direction such as a sudden turning to the southwest cannot be ruled out.
Hurricanes get their energy from the evaporation of the warm surface water. If they hit land during their move ("shore leave"), their energy supply weakens and they lose strength. Regions deeper inland are therefore less affected by the wind speed. Since there are also large masses of water in the clouds in the hurricane catchment area, the raining of these clouds as a tropical cyclone can bring gigantic amounts of precipitation even hundreds of kilometers from the coast .
Predicting the direction of migration and the strength of hurricanes is important in order to warn the population in the affected regions in good time and, if necessary, to evacuate them.
According to the current state of knowledge, the position of the Azores high is decisive for the “path” of the hurricanes in the long term . At the current position, which has been the Azores high since 1000 BP and previously between 5000 and 3400 BP, hurricanes are reaching both the Atlantic and Gulf coasts. The Azores high was between 3400 and 1000 BP further to the southwest, about over Bermuda, and therefore directed significantly more hurricanes into the Gulf of Mexico. Paleotempestological studies showed that three to five times more hurricanes reached the Gulf coast during this time, but only half as many hit the Atlantic coast.
Names of hurricanes
Originally only special hurricanes were given a name, such as "New England Hurricane". In 1950, the National Weather Service began naming the hurricanes. In that year and in the following year, names were initially used that corresponded to the international phonetic alphabet of the time - Able, Baker, Charlie and so on. English women's names were introduced in 1953. From 1960 onwards, predetermined lists of names with 21 names each were used. The number 21 was determined because the most active Atlantic hurricane season in 1933 with 21 registered tropical cyclones had the highest activity until then; so far it has only been exceeded in 2005 . In 1979, male and female names were used alternately for the first time, and French and Spanish names were added to the list of names used.
There are currently six fixed lists of names established by the World Meteorological Organization (WMO) that are used every six years. For example, in the Atlantic and Eastern Pacific in 2012, the lists from 2006 will be used again in 2012 , with the exception of the names that are deleted by the WMO. This is done at the request of the meteorological service of one of the affected countries by resolution of the World Meteorological Organization, if a hurricane has caused particularly severe damage. For example, the name "Ivan", along with three other names that were used in 2004, was no longer in the list for 2010 - "Ivan" was replaced by "Igor". Most of the season's storm names - five - have so far been removed from the list of names used in 2005: Dennis , Katrina , Rita , Stan and Wilma .
While the first storm of each year in the Atlantic and Eastern Pacific always gets a name that begins with an A, in the Central Pacific (starting at 140 ° West) the next name on the list is given, regardless of year or letter.
Example: The Atlantic tropical cyclone before Hurricane “Katrina” was named “Jose”. "Katrina" was followed by "Lee" and "Maria". Since the first named storm of each year begins with "A", it is easy to see how many storms there have been: "Katrina" was the 11th storm of 2005, "Maria" the 13th.
If this “name supply” is not sufficient in one year, the following tropical storms are named according to the Greek alphabet . This happened for the first time and for the only time so far in the 2005 season, when the 22nd tropical storm of the Alpha season , the 23rd Beta , the 24th Gamma , the 25th Delta and the 26th Epsilon were named. Tropical storm number 27, which only occurred a month after the official season, was therefore called Zeta , and another would have been named Eta. Should one of the storms named after the Greek alphabet cause such severe damage that the name is removed from the list, the storm name will be determined to be deleted, but the name will still be available in the future.
Female hurricanes cause more serious injuries and deaths on average than those with male names. This is because femininity and destruction are not so strongly associated and some are therefore subconsciously more careless.
- Great hurricane of 1780 , Caribbean
- Galveston Hurricane 1900, USA
- Okeechobee Hurricane 1928, USA
- Labor Day Hurricane 1935, USA
- Hurricane Hattie 1961, Central America
- Hurricane Flora 1963, Caribbean
- Hurricane Dora (1964) , 1964, USA
- Hurricane Camille 1969, USA
- Hurricane Ginger 1971, North Carolina, Atlantic Ocean
- Hurricane Fifi 1974, Honduras, Belize, Guatemala (8,000 to 10,000 dead)
- Hurricane David 1979, Caribbean (approx. 4,000 dead)
- Hurricane Allen 1980, Caribbean
- Hurricane Gilbert 1988, Caribbean
- Hurricane Hugo , 1989, Caribbean, USA
- Hurricane Andrew 1992, USA
- Hurricane Mitch 1998, Nicaragua , Honduras
- Hurricane Charley 2004, Cuba, USA
- Hurricane Frances 2004, Bahamas , USA
- Hurricane Ivan 2004, Grenada, Jamaica, Cuba, USA
- Hurricane Jeanne 2004, Haiti , USA
- Hurricane Dennis 2005, Cuba, USA
- Hurricane Katrina 2005, USA
- Hurricane Rita 2005, Cuba, USA
- Hurricane Stan 2005, Central America
- Hurricane Vince 2005, Azores, Canaries, Spain
- Hurricane Wilma 2005, Mexico, USA
- Hurricane Dean 2007, Mexico, Belize, Caribbean
- Hurricane Felix 2007, Nicaragua, Honduras
- Hurricane Ike 2008, Cuba, USA
- Hurricane Irene 2011, USA
- Hurricane Sandy 2012, Caribbean, USA
- Hurricane Matthew 2016, Colombia, USA
- Hurricane Irma 2017, Caribbean, USA
- Hurricane Florence 2018, (east coast)
- Hurricane Michael 2018, USA (Gulf of Mexico / Florida)
- Hurricane Leslie 2018
- Hurricane Catarina 2004, southern Brazil
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- List of tropical storms (English)
- List of hurricane seasons (English)
- List of most US hurricanes (English)
- Current Hurricane Information (English)
- Items from the MIT increasing threat potential (English)
- Updated hurricane page on naturgewalten.de
- Detailed hurricane information in the Wiki of the Central for Education Media e. V.
- English-language, graphic map archive by Steven Babin and Ray Sterner with the paths of American hurricanes.
- Full list of assigned names for tropical cyclones worldwide (English)
- Hurricane database
- Short films with satellite images of selected cyclones ( ZAMG )
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