Everything about Mediterranean Climate totally explained
A
Mediterranean climate is one that resembles the
climate of the lands in the
Mediterranean Basin, which includes over half of the area with this climate type world-wide. In addition to the areas surrounding the Mediterranean Sea, this climate type prevails in parts of western
North America, in parts of
Western and
South Australia, in southwestern
South Africa and in parts of central
Chile.
The climate is characterized by hot, dry summers and cool, wet winters. For example, the city of
Perth, Australia, in the
southern hemisphere winter months of June-August, experiences 450 mm (17.7 inches) of rainfall and an average daily minimum of 8°
C (46°
F). Meanwhile during the summer months of December to February the city only averages 32mm (1.3 inches).
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.
The
Mediterranean forests, woodlands, and shrub 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 (for example competition and predation) controls become increasingly important as the discharge declines, and environmental controls regain dominance as environmental conditions become very harsh (for example hot and dry); as a result, these communities are well suited to recover from
droughts,
floods, and
fires.
Rainfall
During summer, regions of Mediterranean climate (also known as Dry-Summer Subtropical for the
Csa areas) are dominated by subtropical high pressure cells, with dry sinking air capping a surface marine layer of varying humidity but making rainfall impossible or unlikely but for the odd 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 the
winter season, and may go anywhere from 2-5 months during the
summer without having any significant precipitation.
Toward the equatorial end, winter precipitation increases. Toward the polar end, total moisture usually increases; in Europe there's 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.
Temperature
All regions with Mediterranean climates have relatively mild winters, but summer temperatures are variable depending on the region. For instance,
Athens,
Greece experiences rather high temperatures in the summer (48.0 °C has been measured in
Eleusina), whereas
San Francisco has cool, mild summers due to the
upwelling of cold subsurface waters along the coast. 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 temperatures during the summer is large, except along the immediate coasts due to dry and clear conditions). Temperatures during winter only occasionally reach freezing and
snow only rarely occurs at sea level, but often in surrounding mountains due to wet conditions. In the winter, 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 don't reach the highest readings found in adjacent
desert regions due to cooling from water bodies, although strong winds from inland desert regions can sometimes boost summer temperatures quickly resulting in a much increased forest fire risk.
Inland locations sheltered from or distant from sea breezes can experience severe heat during the summer. Locations inside the
Sacramento Valley of northern California, for example, are subject to summer temperatures characteristic of hot deserts (often around 40°C/104F), although winters are rainy enough to allow lusher vegetation than is typical in deserts. Unlike the coastal climates that are designated
Csb in the
Köppen climate classification—characteristic of places with cooler summers—the hotter, typically inland areas have the
Csa classification that indicates a hot summer.
Porto,
Portugal, experiences the typical Mediterranean pattern of cool, rainy winters and very dry summers, but has relatively mild average summer temperatures.
On another note, locations that are slightly higher latitude or elevation and 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 and Umpqua Basins of southwestern Oregon, central Spain, southeastern France away from the immediate coastline, northern Italy, and northern Greece. In these areas, plants that are commonly associated with milder Mediterranean climates, such as
citrus can be frozen to death 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); 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.
Natural vegetation
The natural vegetation of Mediterranean lands has to survive long, hot periods of summer droughts. Mediterranean vegetation includes the following:
Most natural vegetation in Mediterranean areas has long since been cleared for agriculture. In places such as the
Sacramento Valley in
California, irrigation has led to intensive farming. Lands in Mediterranean areas, the natural vegetation has been overgrazed by
sheep and
goats. This has exposed the soil to severe
erosion by sudden, heavy rainstorms.
Examples
Northern hemisphere
Further Information
Get more info on 'Mediterranean Climate'.
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