The Azores High also known as North Atlantic (Subtropical) High/Anticyclone or the Bermuda- High, is a large
subtropical semi-permanent centre of
high atmospheric pressure typically found south of the
Azores in the
Atlantic Ocean
The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...
, 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
North Africa (sometimes Northern Africa) is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region. However, it is sometimes defined as stretching from the Atlantic shores of t ...
,
Western Asia,
Southern Europe, and to a lesser extent, eastern
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
. 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
Bermuda is a British Overseas Territories, British Overseas Territory in the Atlantic Ocean, North Atlantic Ocean. The closest land outside the territory is in the American state of North Carolina, about to the west-northwest.
Bermuda is an ...
, 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
central pressure hovers around 1024
mbar (
hPa) often between Bermuda and
North Carolina
North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...
. Seasonally, the Bermuda High exerts its influence on the eastern United States between late May and October.
This high-pressure
block exhibits
anticyclonic behaviour, circulating the air
clockwise. Due to this direction of movement,
African eastern waves are impelled along the southern periphery of the Azores High away from coastal
West Africa
West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...
towards the
Caribbean
The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...
,
Central America
Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...
, or the
Bahamas
The Bahamas, officially the Commonwealth of The Bahamas, is an archipelagic and island country within the Lucayan Archipelago of the Atlantic Ocean. It contains 97 per cent of the archipelago's land area and 88 per cent of its population. ...
, favouring
tropical cyclogenesis, especially during the
hurricane season.
Variations
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 models depict more westward expansion of the anticyclone in the future. However, during the
winter of 2009–2010, the Azores High was smaller, displaced to the northeast and weaker than usual, allowing
sea surface temperatures in the Central Atlantic to increase quickly.
See also
*
Asiatic Low
*
Hadley cell
*
Cold front
*
Mediterranean tropical cyclone
References
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*
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High
Anticyclones
Regional climate effects
Atlantic Ocean
Climate of Portugal