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Encyclopedia > Subtropical cyclone
Image:Http://upload.wikimedia.org/wikipedia/commons/thumb/3/34/Subtropical Storm Andrea 2007.jpg/235px-Subtropical Storm Andrea 2007.jpg

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 latitude, from the equator to 50°. Current storm status Subtropical storm (1-min mean) As of: 2 a. ... The 2007 Atlantic hurricane season is an ongoing event in the annual cycle of tropical cyclone formation. ... Weather is a term that encompasses phenomena in the atmosphere of a planet. ... Cyclone Catarina, a rare South Atlantic tropical cyclone viewed from the International Space Station on March 26, 2004 Hurricane and Typhoon redirect here. ... A fictitious synoptic chart of an extratropical cyclone affecting the UK & Ireland. ... Latitude, usually denoted symbolically by the Greek letter phi, , gives the location of a place on Earth north or south of the equator. ... World map showing the equator in red In tourist areas, the equator is often marked on the sides of roads The equator marked as it crosses Ilhéu das Rolas, in São Tomé and Príncipe. ...

Contents

Types

Upper-level low

The most common type of subtropical storm is an upper-level cold low with circulation extending to the surface layer and maximum sustained winds generally occurring at a radius of about 100 miles/160 kilometres or more from the centre. In comparison to tropical cyclones, such systems have a relatively broad zone of maximum winds that is located farther from the centre, and typically have a less symmetric wind field and distribution of convection. Cyclone Catarina, a rare South Atlantic tropical cyclone viewed from the International Space Station on March 26, 2004 Hurricane and Typhoon redirect here. ...


Mesoscale low

A second type of subtropical cyclone is a mesoscale low originating in or near a frontolyzing zone of horizontal wind shear, also known as a dying frontal zone, with radius of maximum sustained winds generally less 30 miles/50 kilometres. The entire circulation may initially have a diameter of less than 100 miles/160 kilometres. These generally short-lived systems may be either cold core or warm core, and briefly in 1972 this type of subtropical cyclone was referred to a neutercane. As of 2006, the warm core variety were moved under the umbrella of the tropical cyclone definition, and removed from the subtropical cyclone definition. [1] For the Manfred Mann album, see 2006 (album). ... Cyclone Catarina, a rare South Atlantic tropical cyclone viewed from the International Space Station on March 26, 2004 Hurricane and Typhoon redirect here. ...


Transition from extratropical

By gaining tropical characteristics, an extratropical low may transit into a subtropical depression/storm. A subtropical depression/storm may further gain tropical characteristics to become a pure tropical depression/storm, which may eventually develop into a hurricane, and there is at least one case of a tropical storm transforming into a subtropical storm. Generally, a tropical storm or tropical depression is not called subtropical while it is becoming extratropical, after hitting either land or colder waters. This transition normally requires significant instability through the atmosphere, with temperature differences between the underlying ocean and the mid-levels of the troposphere requiring over 40 °C of contrast in this roughly 20,000 foot/6000 meter layer of the lower atmosphere. [2] A mid-latitude cyclone or extratropical cyclone is a weather phenomenon associated with atmospheric low pressure that takes place in the temperate region between the tropical and polar regions. ... This article is about weather phenomena. ... This article is about weather phenomena. ... Cyclone Catarina, a rare South Atlantic tropical cyclone viewed from the International Space Station on March 26, 2004. ... Extratropical is a term used in advisories and tropical summaries to indicate that a cyclone has lost its tropical characteristics. ... Atmosphere diagram showing the mesosphere and other layers. ...


Characteristics

These storms can have maximum winds extending further from the centre than in a purely tropical cyclone. The maximum recorded wind speed for a subtropical storm is 33 m/s (119 km/h, 65 knots, or 74 mph), also the minimum for a hurricane. In the Atlantic Basin, the United States NOAA classifies subtropical cyclones similar to their tropical cousins, based on maximum sustained surface winds. Those with winds below 18 m/s, 65 km/h, 35 kts, or 39 MPH are called subtropical depressions, while those at or above this velocity are referred to as subtropical storms.[3] This article or section cites very few or no references or sources. ... Cyclone Catarina, a rare South Atlantic tropical cyclone viewed from the International Space Station on March 26, 2004 Hurricane and Typhoon redirect here. ... This article or section does not adequately cite its references or sources. ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... Kilometre per hour (American spelling: kilometer per hour) is a unit of both speed (scalar) and velocity (vector). ... A knot is a non SI unit of speed equal to one nautical mile per hour. ... Miles per hour is a unit of speed, expressing the number of international miles covered per hour. ... “Atlantic” redirects here. ... The National Oceanic and Atmospheric Administration (NOAA) is a scientific agency of the United States Department of Commerce focused on the conditions of the oceans and the atmosphere. ... An open surface with X-, Y-, and Z-contours shown. ... This article or section cites very few or no references or sources. ... This article or section does not cite its references or sources. ...


Subtropical cyclones are also more likely than tropical cyclones to form outside of a region's designated hurricane season. Examples include Subtropical Storm Ana (which became Tropical Storm Ana) in mid-April of the 2003 hurricane season and Subtropical Storm Andrea in early May of the 2007 Atlantic hurricane season. Hurricane seaons can refer to : The Atlantic hurricane season The Pacific hurricane season This is a disambiguation page — a navigational aid which lists pages that might otherwise share the same title. ... 2 B C D 6 7 E 9 F G H I 14 J K L M N O P Categories: | | | | ... First storm formed: April 20, 2003 Last storm dissipated: Dec. ... The 2007 Atlantic hurricane season is an ongoing event in the annual cycle of tropical cyclone formation. ...


Formation

Most subtropical cyclones form when a deep cold-core extratropical cyclone drops down into the subtropics. The system becomes blocked by a high latitude ridge, and eventually sheds its frontal boundaries as its source of cool and dry air from the high latitudes diverts away from the system. Temperature differences between the 500 hPa pressure level, or 6000 meters/20000 ft above ground level, and the sea surface temperatures initially exceed the dry adiabatic lapse rate, which causes an initial round of thunderstorms at a distance east of the center. Due to the initial cold temperatures aloft, sea surface temperatures usually need to reach at least 20 degrees C for this initial round of thunderstorms. The initial thunderstorm activity moistens up the environment around the low, which destabilizes the atmosphere by reducing the lapse rate needed for convection. When the next shortwave or upper level jet streak moves nearby, convection reignites closer to the center and the system develops into a true subtropical cyclone. The average sea surface temperature that helps lead to subtropical cyclogenesis is 24 degrees C.[2] If the thunderstorm activity becomes deep and persistent, allowing its initial low level warm core to deepen, tropical cyclogenesis is possible. A fictitious synoptic chart of an extratropical cyclone affecting the UK & Ireland. ... The lapse rate is the rate at which an atmospheric variable (usually temperature) decreases with altitude. ... A shelf cloud associated with a heavy or severe thunderstorm over Enschede, The Netherlands. ... The lapse rate is the rate at which an atmospheric variable (usually temperature) decreases with altitude. ... Global Tropical Cyclone Tracks Cyclogenesis is the technical term describing the development or strengthening of a surface low pressure system, or cyclone, in the atmosphere. ...


History of term

Throughout the 1950s and 1960s, the term semi-tropical was used for what would become known as subtropical cyclones. The term subtropical cyclone merely referred to any cyclone located in the subtropical belt near and just north of the horse latitudes. Intense debate ensued in the late 1960s, after a number of subtropical cyclones formed in the Atlantic Basin. In 1972, the National Hurricane Center (NHC) finally designated these storms as subtropical cyclones in real-time, and updated the hurricane database to include subtropical cyclones from 1968–1971. Subtropical cyclones were initially named from the phoenic alphabet list in the early to mid-1970s. In the intervening years of 1975-2001, subtropical storms were either named from the traditional list and considered tropical in real-time, or used a separate numbering system. Between 1992 and 2001, two different numbers were given to subtropical depressions or subtropical storms, one for public use, the other one for NRL and NHC reference. For example, Karen in 2001 was initially known as Subtropical Storm One as well as AL1301 (or 13L for short).[4] In 2002, the NHC began giving numbers to subtropical depressions and names to subtropical storms from the same sequence as tropical cyclones. From 2002 onwards, Subtropical Depression 13L will be known as Subtropical Depression Thirteen instead. Subtropical Storm Nicole, from the 2004 Atlantic hurricane season was the first subtropical storm that did not become tropical since the policy change. A subtropical storm from the 2005 Atlantic hurricane season also did not become tropical, but was not named since it was not recognized until post-season analysis.[5] The 2007 hurricane season began early with Subtropical Storm Andrea. This does not cite its references or sources. ... The 1960s decade refers to the years from January 1, 1960 to December 31, 1969, inclusive. ... Horse latitudes or Subtropical High are subtropical latitudes between 30 and 35 degrees both north and south, characterized by light winds and hot, dry weather, caused by descending air. ... 1972 (MCMLXXII) was a leap year starting on Saturday. ... National Weather Service Logo The U.S. National Hurricane Center is the division of National Weather Services Tropical Prediction Center responsible for tracking and predicting the likely behavior of tropical depressions, tropical storms and hurricanes. ... The 1970s decade refers to the years from 1970 to 1979, In the Western world, the focus shifted from the social activism of the sixties to social activities for ones own pleasure, save for environmentalism, which continued in a very visible way. ... 1975 (MCMLXXV) was a common year starting on Wednesday. ... 2001 (MMI) was a common year starting on Monday of the Gregorian calendar. ... 1992 (MCMXCII) was a leap year starting on Wednesday. ... 2001 (MMI) was a common year starting on Monday of the Gregorian calendar. ... Lowest pressure 986 mbar (hPa; 29. ... The 2004 Atlantic hurricane season officially began on June 1, 2004, and lasted until November 30, 2004. ... The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history, shattering previous records on repeated occasions. ... 2007 hurricane season may refer to: the 2007 Atlantic hurricane season, or the 2007 Pacific hurricane season. ... Lowest pressure 1002 mbar (hPa; 29. ...


See also

Tropical cyclones Portal
Cyclones and Anticyclones of the world
v  d  e
Extratropical - Meso-scale - Polar - Polar low - Subtropical - Tropical

Image File history File links Download high resolution version (1000x662, 320 KB) http://eol. ... Radar image of a tropical cyclone in the northern hemisphere. ... In meteorology, an anticyclone (that is, opposite to a cyclone) is a weather phenomenon in which there is a descending movement of the air and a high pressure area over the part of the planets surface affected by it. ... A fictitious synoptic chart of an extratropical cyclone affecting the UK & Ireland. ... It has been suggested that this article or section be merged into Supercell. ... Polar cyclones (also known as Arctic Cyclones) are vast areas of low pressure. ... Polar low over the Barents Sea on February 27, 1987 A polar low is a small-scale, short-lived atmospheric low pressure system (depression) that is found over the ocean areas poleward of the main polar front in both the Northern and Southern Hemispheres. ... Cyclone Catarina, a rare South Atlantic tropical cyclone viewed from the International Space Station on March 26, 2004 Hurricane and Typhoon redirect here. ...

References

  1. ^ NOAA. Interdepartmental Hurricane Conference Retrieved 2006-10-10.
  2. ^ a b David Mark Roth (2002-02-15). A Fifty year History of Subtropical Cyclones. Hydrometeorological Prediction Center. Retrieved on 2006-10-04.
  3. ^ National Hurricane Center. Glossary of NHC terms. Retrieved on 2007-05-05.
  4. ^ National Hurricane Center. Subtropical Storm One Public Advisory from 2001. Retrieved on 2007-05-05.
  5. ^ Jack Beven and Eric S. Blake. Unnamed Subtropical Storm. Retrieved on 2007-05-05.

For the Manfred Mann album, see 2006 (album). ... October 4 is the 277th day of the year (278th in leap years) in the Gregorian calendar. ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini era. ... May 5 is the 125th day of the year in the Gregorian calendar (126th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini era. ... May 5 is the 125th day of the year in the Gregorian calendar (126th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the Anno Domini era. ... May 5 is the 125th day of the year in the Gregorian calendar (126th in leap years). ...

External links


  Results from FactBites:
 
National Hurricane Center Glossary Terms - Table - MSN Encarta (1494 words)
The term implies both poleward displacement of the cyclone and the conversion of the cyclone's primary energy source from the release of latent heat of condensation to baroclinic (the temperature contrast between warm and cold air masses) processes.
A subtropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) is 33 knot (62 km/h or 38 mph) or less.
A subtropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) is 34 knot (63 km/h or 39 mph) or more.
hurrdef (1538 words)
Subtropical cyclones are generally of two types: (1) An upper level cold low with circulation extending to the surface and maximum sustained winds generally occurring at a radius of about 100 miles or more from the pressure center.
A subtropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) is 33 kt (38 mph or 62 kph) or less.
A subtropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) is 34 kt (39 mph or 63 kph) or more.
  More results at FactBites »

 
 

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