Sirocco

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The winds of the Mediterranean

Sirocco ( /sɪˈrɒk/ ), scirocco, jugo or, rarely, siroc (Catalan : Xaloc; Sicilian : Sciroccu; Greek : Σορόκος; Italian : Scirocco; Spanish : Siroco; Maltese : Xlokk; Occitan : Siròc, Eisseròc; Croatian : Jugo, literally southerly; Libyan Arabic: Ghibli; Egypt: khamsin; Tunisia: ch'hilli) is a Mediterranean wind that comes from the Sahara and can reach hurricane speeds in North Africa and Southern Europe, especially during the summer season.

Catalan language Romance language

Catalan is a Western Romance language derived from Vulgar Latin and named after the medieval Principality of Catalonia, in northeastern modern Spain. It is the only official language of Andorra, and a co-official language of the Spanish autonomous communities of Catalonia, the Balearic Islands and Valencia. It also has semi-official status in the Italian commune of Alghero. It is also spoken in the eastern strip of Aragon, in some villages of Region of Murcia called Carche and in the Pyrénées-Orientales department of France. These territories are often called Països Catalans or "Catalan Countries".

Sicilian language Italo-Dalmatian language spoken in Southern Italy

Sicilian, also known as Siculo or Calabro-Sicilian, is a Romance language spoken on the island of Sicily and its satellite islands. It is also spoken in southern Calabria, specifically in the Province of Reggio Calabria, whose dialect is viewed as being part of the continuum of the Sicilian language. Central Calabria, the southern parts of Apulia and Campania, on the Italian peninsula, are viewed by some as being part of a broader Far Southern Italian language group.

Greek language language spoken in Greece, Cyprus and Southern Albania

Greek is an independent branch of the Indo-European family of languages, native to Greece, Cyprus and other parts of the Eastern Mediterranean and the Black Sea. It has the longest documented history of any living Indo-European language, spanning more than 3000 years of written records. Its writing system has been the Greek alphabet for the major part of its history; other systems, such as Linear B and the Cypriot syllabary, were used previously. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic, and many other writing systems.

Contents

Sirocco wind diagram by Piotr Flatau Sirocco wind1.jpg
Sirocco wind diagram by Piotr Flatau

Development

It arises from a warm, dry, tropical airmass that is pulled northward by low-pressure cells moving eastward across the Mediterranean Sea, with the wind originating in the Arabian or Sahara deserts. [1] The hotter, drier continental air mixes with the cooler, wetter air of the maritime cyclone, and the counter-clockwise circulation of the low propels the mixed air across the southern coasts of Europe.

Mediterranean Sea Sea connected to the Atlantic Ocean between Europe, Africa and Asia

The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Southern Europe and Anatolia, on the south by North Africa and on the east by the Levant. Although the sea is sometimes considered a part of the Atlantic Ocean, it is usually identified as a separate body of water. Geological evidence indicates that around 5.9 million years ago, the Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years, the Messinian salinity crisis, before being refilled by the Zanclean flood about 5.3 million years ago.

Desert Area of land where little precipitation occurs

A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of denudation. About one-third of the land surface of the world is arid or semi-arid. This includes much of the polar regions where little precipitation occurs and which are sometimes called polar deserts or "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location.

Cyclone large scale air mass that rotates around a strong center of low pressure

In meteorology, a cyclone is a large scale air mass that rotates around a strong center of low atmospheric pressure. Cyclones are characterized by inward spiraling winds that rotate about a zone of low pressure. The largest low-pressure systems are polar vortices and extratropical cyclones of the largest scale. Warm-core cyclones such as tropical cyclones and subtropical cyclones also lie within the synoptic scale. Mesocyclones, tornadoes and dust devils lie within smaller mesoscale. Upper level cyclones can exist without the presence of a surface low, and can pinch off from the base of the tropical upper tropospheric trough during the summer months in the Northern Hemisphere. Cyclones have also been seen on extraterrestrial planets, such as Mars and Neptune. Cyclogenesis is the process of cyclone formation and intensification. Extratropical cyclones begin as waves in large regions of enhanced mid-latitude temperature contrasts called baroclinic zones. These zones contract and form weather fronts as the cyclonic circulation closes and intensifies. Later in their life cycle, extratropical cyclones occlude as cold air masses undercut the warmer air and become cold core systems. A cyclone's track is guided over the course of its 2 to 6 day life cycle by the steering flow of the subtropical jet stream.

Effects

The sirocco causes dusty dry conditions along the northern coast of Africa, storms in the Mediterranean Sea, and cool wet weather in Europe. The sirocco's duration may be as short as half a day or may last several days. While passing over the Mediterranean Sea, the sirocco picks up moisture; this results in rainfall in the southern part of Italy, known locally as "blood rain" due to the red sand mixed with the falling rain. Many people attribute health problems to the sirocco, either because of the heat and dust along the African coastal regions, or because of the cool dampness in Europe. The dust within the sirocco winds can cause abrasion in mechanical devices and penetrate buildings.

Italy republic in Southern Europe

Italy, officially the Italian Republic, is a country in Southern Europe. Located in the middle of the Mediterranean Sea, Italy shares open land borders with France, Switzerland, Austria, Slovenia and the enclaved microstates San Marino and Vatican City. Italy covers an area of 301,340 km2 (116,350 sq mi) and has a largely temperate seasonal and Mediterranean climate. With around 61 million inhabitants, it is the fourth-most populous EU member state and the most populous country in Southern Europe.

Sirocco winds with speeds of up to 100 kilometres per hour (54 knots) are most common during autumn and spring. They reach a peak in March and in November when it is very hot.

When combined with a rising tide, the sirocco can cause the acqua alta phenomenon in the Venetian Lagoon.

<i>Acqua alta</i> exceptional tide peaks in Venice and northern Adriatic Sea

Acqua alta is the term used in Veneto for the exceptional tide peaks that occur periodically in the northern Adriatic Sea. The peaks reach their maximum in the Venetian Lagoon, where they cause partial flooding of Venice and Chioggia; flooding also occurs elsewhere around the northern Adriatic, for instance at Grado and Trieste, but much less often and to a lesser degree.

Venetian Lagoon enclosed bay of the Adriatic Sea

The Venetian Lagoon is an enclosed bay of the Adriatic Sea, in northern Italy, in which the city of Venice is situated. Its name in the Italian and Venetian languages, Laguna Veneta—cognate of Latin lacus, "lake"—has provided the english name for an enclosed, shallow embayment of salt water, a lagoon.

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Dust storm meteorological phenomenon common in arid and semi-arid regions

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Mistral (wind) wind in France

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Sahara desert in Africa

The Sahara is a desert located on the African continent. It is the largest hot desert in the world, and the third largest desert overall after Antarctica and the Arctic. Its area of 9,200,000 square kilometres (3,600,000 sq mi) is comparable to the area of China or the United States. The name 'Sahara' is derived from a dialectal Arabic word for "desert", ṣaḥra.

Foehn wind type of dry down-slope wind

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Oceanic climate a type of climate characterised by cool summers and cool winters

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Trade winds

The trade winds are the prevailing pattern of surface winds from the east toward the west (easterly) found in the tropics, within the lower portion of the Earth's atmosphere, in the lower part of the troposphere near the Earth's equator. The trade winds blow predominantly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere, strengthening during the winter and when the Arctic oscillation is in its warm phase. Trade winds have been used by captains of sailing ships to cross the world's oceans for centuries, and enabled colonial expansion into the Americas and trade routes to become established across the Atlantic and Pacific oceans.

Harmattan season in the West African subcontinent which occurs between the end of November and the middle of March

The Harmattan is a season in the West African subcontinent, which occurs between the end of November and the middle of March. It is characterized by the dry and dusty northeasterly trade wind, of the same name, which blows from the Sahara Desert over West Africa into the Gulf of Guinea. The name is related to the word haramata in the Twi language. The temperature is cold in most places, but can also be hot in certain places, depending on local circumstances.

Berg wind hot, dry foehn-type wind in South Africa

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Mineral dust

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Climate of the British Isles

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Thermal low

Thermal lows, or heat lows, are non-frontal low-pressure areas that occur over the continents in the subtropics during the warm season, as the result of intense heating when compared to their surrounding environments. Thermal lows occur near the Sonoran Desert, on the Mexican plateau, in California's Great Central Valley, the Sahara, over north-west Argentina in South America, over the Kimberley region of north-west Australia, the Iberian peninsula, and the Tibetan plateau.

Climate of Los Angeles

The Climate of Los Angeles is a year-round mild-to-hot and mostly dry climate for the LA metropolitan area in California. The climate is classified as a Mediterranean climate, which is a type of dry subtropical climate. It is characterized by seasonal changes in rainfall—with a dry summer and a winter rainy season. Under the modified Köppen climate classification, the coastal areas are classified as Csb, and the inland areas as Csa.

Lodos

The lodos is the strong south-westerly wind which may predominate episodically in the Aegean Sea and Marmara Sea as well as the Mediterranean coast of Turkey all the year round; it frequently raises high seas and may give violent westerly squalls. The word lodos is Turkish, coming from Greek word "Notus", and originally means "southern wind".

Earth rainfall climatology

Earth rainfall climatology Is the study of rainfall, a sub-field of Meteorology. Formally, a wider study includes water falling as ice crystals, i.e. hail, sleet, snow. The aim of rainfall climatology is to measure, understand and predict rain distribution across different regions of planet Earth, a factor of air pressure, humidity, topography, cloud type and raindrop size, via direct measurement and remote sensing data acquisition. Current technologies accurately predict rainfall 3–4 days in advance using numerical weather prediction. Geostationary orbiting satellites gather IR and visual wavelength data to measure realtime localised rainfall by estimating cloud albedo, water content, and the corresponding probability of rain. Geographic distribution of rain is largely governed by climate type, topography and habitat humidity. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation. On the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. The movement of the monsoon trough, or intertropical convergence zone, brings rainy seasons to savannah climes. The urban heat island effect leads to increased rainfall, both in amounts and intensity, downwind of cities. Global warming may also cause changes in the precipitation pattern globally, including wetter conditions at high latitudes and in some wet tropical areas, and drier conditions in parts of the subtropics and middle latitudes. Precipitation is a major component of the water cycle, and is responsible for depositing most of the fresh water on the planet. Approximately 505,000 cubic kilometres (121,000 cu mi) of water falls as precipitation each year; 398,000 cubic kilometres (95,000 cu mi) of it over the oceans. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres (39 in). Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes.

References

  1. Golden Gate Weather Services. Names of Winds. Retrieved on 2006-12-28.