{{Short description|High air pressure area in the Atlantic Ocean}} The '''Azores High''' also known as '''North Atlantic (Subtropical) High/Anticyclone''' or the '''Bermuda High''', is a large [[subtropics|subtropical]] semi-permanent centre of [[high-pressure area|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 [[climate|climatic]] patterns of vast areas of [[North Africa]], [[Western Asia]], [[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 (atmosphere)|subsidence]] and sinking motion of air in the system.
In its summer position, the high is centered near [[Bermuda]], and often referred to as the Bermuda High. In the Northern Hemisphere summer, the Bermuda High often migrates in the area between Bermuda and the East Coast of the United States. When the Bermuda High moves closer to the United States, this creates a deep southwest flow of hot and humid tropical air toward the [[East Coast of the United States]]. In summer, the Azores-Bermuda High is strongest. The [[atmospheric pressure|central pressure]] hovers around 1024 [[mbar]] ([[hPa]]) often between Bermuda and [[North Carolina]]. Seasonally, the Bermuda High exerts its influence on the eastern United States between late May and October.
This high-pressure [[block (meteorology)|block]] exhibits [[anticyclone|anticyclonic]] behaviour, circulating the air [[clockwise]]. Due to this direction of movement, [[tropical waves|African eastern waves]] are impelled along the southern periphery of the Azores High away from coastal [[West Africa]] towards the [[Caribbean]], [[Central America]], or the [[Bahamas]], favouring [[tropical cyclogenesis]], especially during the [[Atlantic hurricane season|hurricane season]].
[[Image:Tropical waves.jpg|thumb|center|529x529px|Tropical wave formation on the Atlantic Ocean.]]
==Variations== {{see also|North Atlantic Oscillation|Tropical upper tropospheric trough}}
Research into [[global warming]] suggests that it may be intensifying the Bermuda High in some years, independently of oscillations such as [[ENSO]], leading to more precipitation extremes across the [[Southeastern United States]]. Latitudinal displacement of the ridge is also occurring, and [[computer model]]s depict more westward expansion of the anticyclone in the future.<ref>{{cite web|last=Lucas|first=Tim|title=Variable southeast summer rainfall linked to climate change|url=http://www.eurekalert.org/pub_releases/2010-10/du-vss102710.php|work=Duke University|publisher=EurekAlert!|access-date=29 October 2010| archive-url= https://web.archive.org/web/20101030014150/http://www.eurekalert.org/pub_releases/2010-10/du-vss102710.php| archive-date= 30 October 2010 | url-status= live}}</ref><ref>{{cite journal|last=Li|first=Wenhong|author2=Laifang Li|author3-link=Rong Fu|author3=Rong Fu|author4=Yi Deng|author5=Hui Wang|title=Changes to the North Atlantic Subtropical High and Its Role in the Intensification of Summer Rainfall Variability in the Southeastern United States|journal=Journal of Climate|date=October 4, 2010|doi=10.1175/2010JCLI3829.1|issn=1520-0442|volume=24|issue=5|pages=1499–1506|bibcode= 2011JCli...24.1499L |citeseerx=10.1.1.211.2720}}</ref> However, during the [[Global storm activity of early 2010|winter of 2009–2010]], the Azores High was smaller, displaced to the northeast and weaker than usual, allowing [[sea surface temperature]]s in the Central Atlantic to increase quickly.<ref>{{cite web|last=Publications|first=RMS|title=2009 Atlantic Hurricane Season Review and 2010 Season Outlook|url=http://www.rms.com/Publications/RMS_2009_Season_Review_and_2010_Outlook_public.pdf|work=Risk Management Solutions|publisher=RMS Catastrophe Response|access-date=29 October 2010|archive-url=https://web.archive.org/web/20101008121713/http://rms.com/Publications/RMS_2009_Season_Review_and_2010_Outlook_public.pdf|archive-date=8 October 2010|url-status=dead}}</ref>
==See also==
* [[Asiatic Low]] * [[Hadley cell]] * [[Cold front]] * [[Mediterranean tropical cyclone]]
==References== {{reflist}} {{refbegin}} * {{cite web|url=http://www.weatheronline.co.uk/feature/aa030803.htm|title=The Azores High|access-date=2006-11-19|work=WeatherOnline Weather facts}} * {{cite web|url=http://amsglossary.allenpress.com/glossary/search?id=azores-high1|title=Azores high|access-date=2006-11-19|work=Glossary of Meteorology|publisher=[[American Meteorological Society]]| archive-url= https://web.archive.org/web/20061026102309/http://amsglossary.allenpress.com/glossary/search?id=azores-high1| archive-date= 26 October 2006 | url-status= live}} * {{cite web|url=http://amsglossary.allenpress.com/glossary/search?id=bermuda-high1|title=Bermuda high|access-date=2006-11-19|work=Glossary of Meteorology|publisher=[[American Meteorological Society]]| archive-url= https://web.archive.org/web/20061019141218/http://amsglossary.allenpress.com/glossary/search?id=bermuda-high1| archive-date= 19 October 2006 | url-status= live}} {{refend}}
{{Cyclones}}
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[[Category:Azores|High]] [[Category:Anticyclones]] [[Category:Regional climate effects]] [[Category:Atlantic Ocean]] [[Category:Climate of Portugal]]