Hurricane Alley

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Atlantic hurricane tracks from 1851-2012. Atlantic hurricane tracks.jpg
Atlantic hurricane tracks from 1851-2012.

Hurricane Alley is an area of warm water in the Atlantic Ocean stretching from the west coast of northern Africa to the east coast of Central America and Gulf Coast of the Southern United States. Many hurricanes form within this area. The sea surface temperature of the Atlantic in Hurricane Alley has grown slightly warmer over the past decades [1] . A particularly warm summer in 2005 led climate scientists to begin studying whether this trend would lead to an increase in hurricane activity. [2]

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How hurricanes form

The warm waters of Hurricane Alley are depicted in orange Hurricane Alley.jpg
The warm waters of Hurricane Alley are depicted in orange

Hurricanes form over tropical waters in areas of high humidity, light winds, and warm sea surface temperatures. These areas which were described above are usually between the latitudes of 8° and 20° north. [3] The perfect temperature for a hurricane is approximately 26 °C. This temperature has been set as a standard. If the water is colder the hurricane will most likely weaken, but if the waters are warmer rapid growth can occur. [4]

The area between 10° and 20°N create the most hurricanes in a given season because of the warmer temperatures. Hurricanes do not form outside this range because the Coriolis effect is not strong enough to create the tight circulation needed and above this range the temperatures are too cool. [5] The waters are only at the necessary temperatures from July until mid-October. In the Atlantic this is the height of the season.

Since hurricanes rely on sea surface temperature, sometimes an initially active season becomes quiet later. This is because the hurricanes are so strong that they churn the waters and bring colder waters up from the deep. This creates an area of the sea the size of the hurricane, which has cooler waters, which can be 5-10 °C lower than before the hurricane. When a new hurricane moves over the cooler waters they have no fuel to continue to thrive, so they weaken or even die out. [6]

According to an Azores High hypothesis of geographer Kam-biu Liu, an anti-phase pattern is expected to exist between the Gulf of Mexico coast and the North American Atlantic coast. During the quiescent periods (3000–1400 BC, and 1000 AD to present), a more northeasterly position of the Azores High would result in more hurricanes being steered towards the Atlantic coast. During the hyperactive period (1400 BC to 1000 AD), more hurricanes were steered towards the Gulf coast as the Azores High was shifted to a more southwesterly position near the Caribbean. [7] [8] 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 years BP, [9] 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 3,000-year proxy record from a coastal lake in Cape Cod suggests that hurricane activity has increased significantly during the past 500–1,000 years, just as the Gulf coast was amid a quiescent period of the last millennium.[ citation needed ]

See also

Related Research Articles

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Atlantic hurricane tropical cyclone that forms in the North Atlantic Ocean

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Azores High

The Azores High also known as North Atlantic (Subtropical) High/Anticyclone or the Bermuda-Azores High, is a large subtropical semi-permanent centre of high atmospheric pressure typically found south of the Azores in the Atlantic Ocean, at the Horse latitudes. It forms one pole of the North Atlantic oscillation, the other being the Icelandic Low. The system influences the weather and climatic patterns of vast areas of North Africa and southern Europe, and to a lesser extent, eastern North America. The aridity of the Sahara Desert and the summer drought of the Mediterranean Basin is due to the large-scale subsidence and sinking motion of air in the system. In its summer position, the high is centered near Bermuda, and creates a southwest flow of warm tropical air toward the East Coast of the United States. In summer, the Azores-Bermuda High is strongest. The central pressure hovers around 1024 mbar (hPa).

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Climate of North Carolina

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1872 Atlantic hurricane season hurricane season in the Atlantic Ocean

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Meteorological history of Hurricane Sandy

Hurricane Sandy was the fifth-costliest Atlantic hurricane on record. It lasted for over a week in late October-early November 2012. Classified as the eighteenth named storm, tenth hurricane, and second major hurricane of the annual hurricane season, Sandy originated from a tropical wave on October 22. Performing a small loop over the central Caribbean Sea, the system intensified into a tropical storm a day later and became the final hurricane of the season before briefly coming ashore the coast of Jamaica on October 24. After emerging between Jamaica and Cuba, Sandy began a period of rapid intensification into a Category 3 hurricane on the Saffir–Simpson hurricane wind scale, with maximum sustained winds of 115 mph (185 km/h). It made landfall at this intensity near Santiago de Cuba on October 25.

2019 Atlantic hurricane season Hurricane season in the Atlantic Ocean

The 2019 Atlantic hurricane season was the fourth consecutive year of above-average and damaging seasons dating back to 2016. It is tied with 1969 as the fourth-most active Atlantic hurricane season on record in terms of named storms, with 18 named storms and 20 tropical cyclones in total, although many were weak and short-lived, especially towards the end of the season. The season officially began on June 1 and ended on November 30. These dates historically describe the period each year when most tropical cyclones form in the Atlantic basin and are adopted by convention. However, tropical cyclogenesis is possible at any time of the year, as demonstrated by the formation of Subtropical Storm Andrea on May 20, marking the record fifth year in a row where a tropical or subtropical cyclone developed before the official start of the season, breaking the previous record of four consecutive years set in 1951–1954. For a second year in a row, no tropical cyclones formed during the month of June.

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Hurricane Alex (2016) Category 1 Atlantic hurricane in 2016

Hurricane Alex was the first Atlantic hurricane to occur in January since Hurricane Alice in 1955. Alex originated as a non-tropical low near the Bahamas on January 7, 2016. Initially traveling northeast, the system passed by Bermuda on January 8 before turning southeast and deepening. It briefly acquired hurricane-force winds by January 10, then weakened slightly before curving towards the east and later northeast. Acquiring more tropical weather characteristics over time, the system transitioned into a subtropical cyclone well south of the Azores on January 12, becoming the first North Atlantic tropical or subtropical cyclone in January since Tropical Storm Zeta of 2006. Alex continued to develop tropical features while turning north-northeast, and transitioned into a fully tropical cyclone on January 14. The cyclone peaked in strength as a Category 1 hurricane on the Saffir–Simpson scale with maximum sustained winds of 85 mph (140 km/h) and a central pressure of 981 mbar. Alex weakened to a high-end tropical storm before making landfall on Terceira Island on January 15. By that time, the storm was losing its tropical characteristics; it fully transitioned back into a non-tropical cyclone several hours after moving away from the Azores. Alex ultimately merged with another cyclone over the Labrador Sea on January 17.

Paleotempestology The study of past tropical cyclone activity using geological proxies and historical documents

Paleotempestology is the study of past tropical cyclone activity by means of geological proxies as well as historical documentary records. The term was coined by Kerry Emanuel.

References

  1. Goudzari, Sara (May 2, 2006). "Hurricane Alley Heats Up". LiveScience. Retrieved 9 September 2008.
  2. "Hurricane Alley Heats Up". National Aeronautics and Space Administration. August 9, 2005. Retrieved 9 September 2008.
  3. Steve Graham; Holli Riebeek (1 November 2006). "Hurricanes: The Greatest Storms on Earth". NASA . Retrieved 29 July 2013.
  4. "Seeing into the Heart of a Hurricane". Earth Observatory.
  5. "NWS JetStream - Tropical Cyclone Introduction". National Weather Service.
  6. "Seeing into the Heart of a Hurricane". Earth Observatory.
  7. Liu, Kam-biu (1999). Millennial-scale variability in catastrophic hurricane landfalls along the Gulf of Mexico coast. 23d Conf. on Hurricanes and Tropical Meteorology. Dallas, TX: Amer. Meteor. Soc. pp. 374–377.
  8. 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.
  9. 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.

Further reading

See also