Mediterranean climate

A Mediterranean climate is the climate typical of most of the lands in the Mediterranean Basin as part of subtropical climate. Worldwide, this is where the largest area of this climate type is found. Beyond the Mediterranean area, this climatic type prevails in much of California, in parts of Western and South Australia, in southwestern South Africa, in isolated sections of Central Asia and in parts of central Chile.

Contents 1 Characteristics 2 Köppen climate classification 3 Precipitation 4 Temperature 5 Mediterranean Biome 5.1 Natural vegetation 6 Continental Mediterranean Climate 7 Examples 8 Charts of selected cities 8.1 Mediterranean climate 8.1.1 Northern hemisphere 8.1.2 Southern hemisphere 8.2 Continental Mediterranean Climates 9 See also 10 References 11 External links

[edit] Characteristics

The climate is characterised by warm to hot, dry summers and mild to cool, wet winters. Mediterranean climate zones are associated with the five large subtropical high pressure cells of the oceans, the Azores High, South Atlantic High, North Pacific High, South Pacific High, and Indian Ocean High. These high pressure cells shift polarward in the summer and equatorward in the winter, playing a major role in the formation of the world's tropical deserts and the zones of Mediterranean climate polarward of the deserts. For example, the Azores High is associated with the Sahara Desert and the Mediterranean Basin's climate. The South Atlantic High is similarly associated with the Namib Desert and the Mediterranean climate of the western part of South Africa. The North Pacific High is related to the Sonoran Desert and California's climate, while the South Pacific High is related to the Atacama Desert and central Chile's climate, and the Indian Ocean High is related to the deserts of western Australia (Great Sandy Desert, Great Victoria Desert, and Gibson Desert) and the Mediterranean climate of southwest and south-central Australia.^[1]

Most large, historic cities of the Mediterranean basin, including Athens, Barcelona, Beirut, Jerusalem, Lisbon, Madrid, Marseille and Rome, lie within Mediterranean climatic zones, as do major cities outside of the Mediterranean, such as Cape Town, Los Angeles, Adelaide, San Francisco and Santiago de Chile.

[edit] Köppen climate classification

Under the Köppen climate classification, "dry-summer subtropical" climates (classified as Csa, Csb, and Csc) are often referred to as "Mediterranean". Under the Köppen-Geiger system, "C" zones have an average temperature above 10° C. (50° F.) in their warmest months, and an average in the coldest between 18° C. (64° F.) and −3° C. (26.6° F.) (or, in some applications, between 18° C. and 0° C. [32° F.]). The second letter indicates the precipitation pattern: "s" represents dry summers: the driest summer month has, on average, precipitation of less than 30 mm and that is less than one-third that of the wettest winter month. The third letter indicates the degree of summer heat: "a" represents an average temperature in the warmest month above 22° C. (72° F.), with at least four months averaging above 10° C. (50° F.); "b", an average temperature in the warmest month below 22° C., and again with at least four months averaging above 10° C.

Under this classification, dry-summer subtropical climates (Csa, Csb) usually occur on the western sides of continents, and Csb zones include additional areas not typically associated with a typical Mediterranean climate, such as much of the Pacific Northwest, much of southern Chile, parts of west-central Argentina, and northern Spain and Portugal.^[2] Many of these areas would be Oceanic (Cfb) did not their dry-summer patterns meet Koeppen's Cs thresholds, and cities such as Seattle, Portland, and Victoria can be classified as Csb. Additional highland areas in the subtropics also meet Cs requirements, though they, too, are not normally associated with Mediterranean climates.

Under Trewartha's modified Koeppen climate classification, the two major requirements for a Cs climate are revised. Under Trewartha's system, at least eight months must have average temperatures of at least 10° C., and the average annual precipitation must not exceed 900 mm. (35 inches). Thus, under this system, many Csb zones (including the Pacific Northwest), become DO Oceanic.

[edit] Precipitation

“	It [Chile] has four months of winter, no more, and in them, except when there is a quarter moon, when it rains one or two days, all the other days have such beautiful suns...	”
—Pedro de Valdivia to Charles V, Holy Roman Emperor

During summer, regions of Mediterranean climate are dominated by subtropical high pressure cells, with dry sinking air capping a surface marine layer of varying humidity and making rainfall impossible or unlikely except for the occasional thunderstorm, while during winter the polar jet stream and associated periodic storms reach into the lower latitudes of the Mediterranean zones, bringing rain, with snow at higher elevations. As a result, areas with this climate receive almost all of their yearly rainfall during their winter season, and may go anywhere from 4 to 6 months during the summer without having any significant precipitation.

Toward the equatorial latitudes, winter precipitation increases as a share of annual precipitation as the climate grades equatorward into the steppe climate usually characterized as BSHs normally too dry to support unirrigated agriculture. Toward the polar latitudes, total moisture usually increases; in Europe there is more summer rain further north while along the American west coast the winters become more intensely wet and the dry seasons shorter as one moves north. In the Pacific Ocean adjacent Mediterranean climate regions the El Niño-Southern Oscillation affects annual precipitation over a given decade.

[edit] Temperature

Most regions with Mediterranean climates generally have relatively mild winters and very warm summers, but winter and summer temperatures are variable depending on the region. In the case of winters for instance, Lisbon experiences very mild temperatures in the winter, with frost and snow practically unknown, whereas Thessaloniki has cold winters with annual frosts and snowfall. In the case of summers for instance, Athens experiences rather high temperatures in the summer (48.0°C has been measured in nearby Eleusina), whereas San Francisco has cool, mild summers due to the upwelling of cold subsurface waters along the coast producing regular summer fog. Because all regions with a Mediterranean climate are near large bodies of water, temperatures are generally moderate with a comparatively small range of temperatures between the winter low and summer high (although the daily range of temperature during the summer is large due to dry and clear conditions, except along the immediate coasts). Temperatures during winter only occasionally reach freezing and snow occurs only rarely at sea level, but often in surrounding mountains because of wet conditions. In the summer, the temperatures range from mild to very warm, depending on distance from the open ocean, elevation, and latitude. Even in the warmest locations with a Mediterranean-type climate, however, temperatures usually do not reach the highest readings found in adjacent desert regions because of cooling from water bodies, although strong winds from inland desert regions can sometimes boost summer temperatures, quickly increasing the risk of Wildfires.

Inland locations sheltered from or distant from sea breezes can experience severe heat during the summer. For example the northern Sacramento Valley and southern San Joaquin Valley regions of the Central Valley of California can experience summer temperatures characteristic of a hot desert (ie: 40°C/104°F) because of high temperature and very low humidity, although their winters are very rainy and foggy enough to allow lusher vegetation than is typical in deserts; the vegetation becomes a fire risk in the dry summers. However the middle region of the Central Valley receives an ocean influence from the San Francisco Bay, due west, known as the "Delta Breeze" which reduces the summer heat. It can even carry coastal fog into the area, with cooler temperatures and higher humidity. Meanwhile more southern coastal cities, such as Los Angeles and San Diego, California exhibit drier borderline semiarid climate conditions within the Mediterranean climate. While the wet-winter, dry-summer precipitation pattern prevails in these cities, winters there are relatively dry by overall Mediterranean climate standards. Coastal climates are normally designated as Csb in the Köppen climate classification as they are characterized by an average temperature of the warmest month below 21.8°C (72°F); the hotter, typically inland areas are classified as Csa, which indicates a hot summer with the average temperature of the warmest month being above 21.8°C (72°F). Csb climates are found in northwestern Iberia, south coastal Brittany (Pornic, Noirmoutier Island, Belle Ile), coastal California and parts of the Pacific Northwest, central Chile and parts of southern Australia while Csa climates are mainly found around the Mediterranean Sea, southwestern Australia (including the city of Perth), southwestern South Africa and in the interior of California. In the northwestern Mediterranean Basin, the rainiest season is divided into a primary maximum during the autumn and a secondary in spring, making for a shorter dry season than in the classic Mediterranean climate as in Barcelona and with some cold days in winter, when the northern winds often bring cool or freezing air from central and northern Europe (usually accompanied by lower temperatures, high pressure and clear skies) but also with some snowstorms. This northern Mediterranean coasts is close to the Cfa Köppen classified humid subtropical climates of the Danube, Po, Garonne and Rhone River valleys.

Locations with either slightly higher latitude or elevation and which are cut off from milder ocean winds may have somewhat colder winters and more distinct seasons with occasional snow. This "temperate Mediterranean" climate is most noticeable in the Rogue River Valley and Umpqua River Basin of southwestern Oregon, the central and northeastern Iberian Peninsula, southeastern France, away from the immediate coastline, northern Italy, and northern Greece. In these areas, some plants, (such as citrus) that are commonly associated with milder Mediterranean climates, will freeze in a severe winter and are thus not part of the regular landscape.

Areas of high altitude adjacent to locations with Mediterranean climates, such as the "mesetas" or plateaus of central Spain, may have the cold winters that are characteristic of a continental climate (see Continental Mediterranean climate below); under Köppen's scheme such places might earn the designation Dsa (at lower latitudes above Csa), Dsb (either at high elevations in the lower latitudes or at lower elevations in the mid-latitudes above Csb) or even Dsc (just below the tree line). An example of a very humid Mediterranean snow climate, Dfsc, is the highest summit on Orjen, Zubacki kabao in the subadriatic Dinaric Alps in Montenegro.

The temperature and rainfall pattern for a Csa or even a Csb climate can exist as a microclimate in some high-altitude locations adjacent to a rare tropical As (summer-drought tropical climate, typically in a rainshadow region.

[edit] Mediterranean Biome

The Mediterranean forests, woodlands, and scrub biome is closely associated with Mediterranean climate zones. Particularly distinctive of the climate are sclerophyll shrublands, called maquis in the Mediterranean Basin, chaparral in California, matorral in Chile, fynbos in South Africa, and mallee and kwongan shrublands in Australia. Aquatic communities in Mediterranean climate regions are adapted to a yearly cycle in which abiotic (environmental) controls of stream populations and community structure dominate during floods, Biotic component (e.g. competition and predation) controls become increasingly important as the discharge declines, and environmental controls regain dominance as environmental conditions become very harsh (i.e. hot and dry); as a result, these communities are well suited to recover from droughts, floods, and fires.^[3]

[edit] Natural vegetation

The native vegetation of Mediterranean climate lands must be adapted to survive long, hot summer droughts and prolonged wet periods in winter. Mediterranean vegetation examples include the following:

• Evergreen trees: such as Pines, Cypress, and Oaks
• Deciduous trees: such as Sycamores, Oaks, and Buckeyes
• Fruit trees such as Olives, Figs, Citrus, and Walnuts
• Shrubs: such as Myrtles, Bay laurel and California laurel, Manzanitas, and Chamise
• Sub-shrubs: such as Sages, Artemisias, and Sagebrush
• Grasses: Grassland types, Bunchgrasses; Sedges, and Rushes
• Herbs: such as fragrant Rosemary, Thyme, and Lavender

Much native vegetation in Mediterranean climate area valleys have been cleared for agriculture. In places such as the Sacramento Valley and Oxnard Plain in California, draining marshes and estuaries combined with supplemental irrigation has led to a century of intensive agriculture. In hillside and mountainous areas, away from urban sprawl, ecosystems and habitats of native vegetation are more sustained.

The fynbos vegetation in the South-western Cape in South Africa is famed for its high floral diversity, and includes such plant types as members of the Restionaceae, Ericas (Heaths) and Proteas. Representatives of the Proteaceae also grow in Australia, such as Banksias.) The palette of California native plants is also renowned for its species and cultivar diversity.

[edit] Continental Mediterranean Climate

Some areas within Mediterranean climatic zones exhibit characteristics of a continental climate due to altitude and inland locations with limited influence of the sea. Although these areas fall within the Cs designation, they share some features typical of continental climates, such as cold and often snowy (but relatively dry) winters and warm to hot summers. The difference between average temperatures in winter and summer is about 18.5°C in most locations, such as in Madrid, Spain. In summer, daily temperatures can exceed 30°C, while snow and frost are a regular occurence in winter. Precipitation patterns are typical of Mediterranean climates- generally 400–600 mm- except with peaks in autumn and spring and a drier stretch in mid-winter. The continental aspects of this climate are more important with higher altitude, where it sometimes gives way to true mountain climates. Continental Mediterranean climates can be found in the interior of the Iberian peninsula (the Meseta and the Ebro valley), inner parts of Anatolia, inland Sicily, inland Central Chile, montane areas of the Pacific Northwest, small pockets of the Southwestern United States, most of Northwestern Iran and parts of montane Central Asia.

In many instances, a Continental Mediterranean climate closely resembles a cold semi-arid climate (Köppen: BSk). However, Continental Mediterranean climates are unlike semi-arid climates in that their annual average precipitation levels are above potential evapotranspiration, whereas semi-arid climates by definition have average precipitation levels below potential evapotranspiration.

[edit] Examples

Notable Cities with Mediterranean Climates

Adelaide, Australia Al Bayda, Libya Algiers, Algeria Antalya, Turkey Athens, Greece (Borderline BSh semi-arid climate) Barcelona, Spain Beirut, Lebanon Cape Town, South Africa Casablanca, Morocco (Borderline BSh semi-arid climate) Dubrovnik, Croatia Dushanbe, Tajikistan Funchal, Portugal Gaza, Gaza Strip Haifa, Israel Heraklion, Greece Izmir, Turkey Jerusalem, Israel Latakia, Syria Limassol, Cyprus Lisbon, Portugal Los Angeles, United States (Borderline BSh semi-arid climate) Marseille, France

Monaco, Monaco Mostar, Bosnia and Herzegovina Naples, Italy Nice, France Palermo, Italy Perth, Australia Podgorica, Montenegro Rabat, Morocco Ramallah, West Bank Rome, Italy San Diego, United States (Borderline BSh semi-arid climate) San Francisco, United States Santiago, Chile Split, Croatia Tashkent, Uzbekistan Tel Aviv, Israel Tirana, Albania Tripoli, Libya Tunis, Tunisia Trebinje, Bosnia and Herzegovina Valencia, Spain Valletta, Malta Valparaiso, Chile

Notable Cities with Continental Mediterranean Climates

• Ankara, Turkey
• Burgos, Spain
• Leon, Spain
• Madrid, Spain

Notable Cities with Csb Climates under the Koeppen-Geiger system, but are generally considered Oceanic Climates

A Coruña, Spain Porto, Portugal Portland, United States Puerto Montt, Chile Seattle, United States Viana do Castelo, Portugal Victoria, Canada

[edit] Charts of selected cities

[edit] Mediterranean climate

[edit] Northern hemisphere

Barcelona
Climate chart (explanation)
J F M A M J J A S O N D     41   13 4     29   15 5     42   16 7     49   18 9     59   21 12     42   24 16     20   28 19     61   28 19     85   26 17     91   22 13     58   17 8     51   14 6 average max. and min. temperatures in °C precipitation totals in mm source: WMO [4]
Imperial conversion J F M A M J J A S O N D     1.6   56 40     1.1   58 42     1.7   61 44     1.9   64 47     2.3   69 54     1.7   76 60     0.8   82 65     2.4   82 67     3.3   78 62     3.6   71 55     2.3   63 47     2   58 42 average max. and min. temperatures in °F precipitation totals in inches

Los Angeles
Climate chart (explanation)
J F M A M J J A S O N D     61   19 9     64   19 10     50   19 10     18   20 12     3.6   21 14     0.8   22 15     0.3   24 17     3.8   25 18     7.9   25 17     8.6   24 15     45   21 12     42   19 9 average max. and min. temperatures in °C precipitation totals in mm source: WMO [5]
Imperial conversion J F M A M J J A S O N D     2.4   66 48     2.5   66 49     2   65 51     0.7   67 53     0.1   69 56     0   72 60     0   75 63     0.1   77 64     0.3   77 63     0.3   74 59     1.8   70 53     1.7   66 48 average max. and min. temperatures in °F precipitation totals in inches

Haifa
Climate chart (explanation)
J F M A M J J A S O N D     125   17 9     92   18 9     53   20 11     24   24 14     2.7   26 17     0   29 21     0   31 23     0   31 24     1.2   30 22     28   28 19     77   24 14     136   19 11 average max. and min. temperatures in °C precipitation totals in mm source: Israel Meteorological Service [6] (Hebrew)
Imperial conversion J F M A M J J A S O N D     4.9   63 48     3.6   64 48     2.1   67 51     0.9   75 56     0.1   79 63     0   85 69     0   88 73     0   89 74     0   86 71     1.1   82 65     3   75 57     5.3   67 52 average max. and min. temperatures in °F precipitation totals in inches

Lisbon
Climate chart (explanation)
J F M A M J J A S O N D     97   15 11     90   16 13     51   18 14     65   19 15     56   21 17     17   25 20     6.1   28 23     6.8   28 23     29   26 22     80   22 18     107   18 15     122   15 12 average max. and min. temperatures in °C precipitation totals in mm source: Instituto de Meteorologia (1971-2000) [7] (Portuguese)
Imperial conversion J F M A M J J A S O N D     3.8   58 52     3.6   61 55     2   65 58     2.5   67 60     2.2   71 63     0.7   77 69     0.2   82 73     0.3   82 73     1.1   79 71     3.1   72 65     4.2   64 59     4.8   59 54 average max. and min. temperatures in °F precipitation totals in inches

[edit] Southern hemisphere

Santiago (Chile)
Climate chart (explanation)
J F M A M J J A S O N D     0.4   30 13     0.6   29 12     3.2   27 11     10   23 8     42   19 6     70   15 4     87   15 4     52   17 5     22   19 6     13   22 8     9.2   25 10     2.1   28 12 average max. and min. temperatures in °C precipitation totals in mm source: WMO [8]
Imperial conversion J F M A M J J A S O N D     0   85 55     0   84 54     0.1   80 51     0.4   74 46     1.7   66 43     2.8   59 40     3.4   59 39     2   62 41     0.9   66 43     0.5   72 47     0.4   78 50     0.1   83 54 average max. and min. temperatures in °F precipitation totals in inches

Adelaide
Climate chart (explanation)
J F M A M J J A S O N D     20   29 17     13   29 17     25   26 15     40   23 12     60   19 10     81   16 8     75   15 7     67   17 8     60   19 10     46   22 11     32   25 14     28   27 16 average max. and min. temperatures in °C precipitation totals in mm source: Australia Bureau of Meteorology [9]
Imperial conversion J F M A M J J A S O N D     0.8   84 63     0.5   85 63     1   79 59     1.6   73 54     2.4   66 50     3.2   61 47     3   60 45     2.6   62 47     2.4   66 49     1.8   71 53     1.3   77 57     1.1   81 60 average max. and min. temperatures in °F precipitation totals in inches

Perth (AUS)
Climate chart (explanation)
J F M A M J J A S O N D     9.5   31 18     13   31 18     19   30 16     44   26 14     118   22 11     177   19 9     170   18 8     134   19 8     81   20 10     52   23 11     22   26 14     13   29 16 average max. and min. temperatures in °C precipitation totals in mm source: Australia Bureau of Meteorology [10]
Imperial conversion J F M A M J J A S O N D     0.4   87 64     0.5   88 64     0.8   85 62     1.7   78 56     4.6   72 51     7   67 47     6.7   65 46     5.3   66 46     3.2   68 49     2.1   73 52     0.9   79 57     0.5   84 61 average max. and min. temperatures in °F precipitation totals in inches

Cape Town
Climate chart (explanation)
J F M A M J J A S O N D     15   26 16     17   27 16     20   25 14     41   23 12     69   20 9     93   18 8     82   18 7     77   18 8     40   19 9     30   21 11     14   24 13     17   25 15 average max. and min. temperatures in °C precipitation totals in mm source: WMO [11]
Imperial conversion J F M A M J J A S O N D     0.6   79 60     0.7   80 60     0.8   78 58     1.6   73 53     2.7   69 49     3.7   65 46     3.2   64 45     3   64 46     1.6   67 48     1.2   70 51     0.6   74 56     0.7   77 59 average max. and min. temperatures in °F precipitation totals in inches

[edit] Continental Mediterranean Climates

Madrid
Climate chart (explanation)
J F M A M J J A S O N D     37   10 3     35   12 4     26   16 6     47   18 7     52   21 11     25   27 15     15   31 18     10   31 18     28   26 15     49   19 10     56   13 6     56   10 4 average max. and min. temperatures in °C precipitation totals in mm source: WMO
Imperial conversion J F M A M J J A S O N D     1.5   49 37     1.4   54 39     1   60 42     1.9   64 45     2   71 51     1   80 59     0.6   88 65     0.4   87 65     1.1   79 59     1.9   66 50     2.2   56 43     2.2   50 39 average max. and min. temperatures in °F precipitation totals in inches

Ankara
Climate chart (explanation)
J F M A M J J A S O N D     40   2 −7     32   4 −5     36   10 −2     52   16 3     49   20 7     33   24 9     14   28 13     12   28 13     18   24 8     30   18 4     38   11 −1     41   4 −3 average max. and min. temperatures in °C precipitation totals in mm source: Weatherbase [12]
Imperial conversion J F M A M J J A S O N D     1.6   35 20     1.3   40 23     1.4   50 29     2   60 38     1.9   68 44     1.3   76 49     0.6   82 55     0.5   83 55     0.7   76 47     1.2   65 39     1.5   51 30     1.6   40 26 average max. and min. temperatures in °F precipitation totals in inches

León
Climate chart (explanation)
J F M A M J J A S O N D     58   7 −1     46   10 0     29   13 2     50   14 3     58   18 6     39   23 10     28   27 12     24   27 12     39   23 10     56   16 6     58   11 3     70   8 1 average max. and min. temperatures in °C precipitation totals in mm source: Agencia Estatal de Meteorología [13] (Spanish)
Imperial conversion J F M A M J J A S O N D     2.3   45 31     1.8   49 33     1.1   55 35     2   58 37     2.3   64 43     1.5   74 49     1.1   81 54     0.9   80 54     1.5   73 50     2.2   62 44     2.3   52 37     2.8   46 33 average max. and min. temperatures in °F precipitation totals in inches

Burgos
Climate chart (explanation)
J F M A M J J A S O N D     46   7 −1     42   9 −1     31   12 1     65   13 2     69   17 6     46   22 8     30   26 11     27   27 11     26   23 9     50   17 5     56   11 2     57   8 0 average max. and min. temperatures in °C precipitation totals in mm source: Agencia Estatal de Meteorología
Imperial conversion J F M A M J J A S O N D     1.8   44 30     1.7   48 31     1.2   54 33     2.6   56 36     2.7   63 42     1.8   72 47     1.2   80 52     1.1   80 52     1   73 47     2   62 42     2.2   51 35     2.2   46 33 average max. and min. temperatures in °F precipitation totals in inches

[edit] See also

• Continental Mediterranean climate (wine)

[edit] References

[edit] External links

• Explanation of Mediterranean Climate (University of Wisconsin)

v • d • e Climate types under the Köppen climate classification Class A Tropical rainforest (Af) · Tropical monsoon (Am) · Tropical savanna (Aw, As) Class B Desert (Bwh, Bwk, Bwn) · Semi-arid (Bsh, Bsk) Class C Humid subtropical (Cfa, Cwa) · Oceanic (Cfb, Cwb, Cfc) · Mediterranean (Csa, Csb) Class D Humid continental (Dfa, Dwa, Dfb, Dwb) · Subarctic (Dfc, Dwc, Dfd, Dwd) Class E Polar (ET, EF) · Alpine (ET/H)

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