There are regular patterns of
prevailing winds found in bands round Earth's
equatorial region. The zone designated the
trade winds is the zone between about 30° N and 30° S, blowing predominantly from the northeast in the
Northern Hemisphere and from the southeast in the
Southern Hemisphere. The
westerlies are the prevailing winds in the
middle latitudes between 30 and 60 degrees
latitude, blowing predominantly from the southwest in the Northern Hemisphere and from the northwest in the Southern Hemisphere. Some of the strongest westerly winds in the middle latitudes can come in the
Roaring Forties of the Southern Hemisphere, between 30 and 50 degrees latitude. Examples of notable rain shadowing include:
Africa Northern Africa ' (top) rain shadow effect makes the
Sahara even drier. • The
Sahara is made even drier because of a strong rain shadow effects caused by major mountain ranges (whose highest points can culminate up to more than 4,000 meters; 2½ miles high). To the northwest, the
Atlas Mountains, covering the
Mediterranean coast for
Morocco,
Algeria and
Tunisia. On the
windward side of the
Atlas Mountains, the warm, moist winds blowing from the northwest off the
Atlantic Ocean, which contain a lot of water vapor, are forced to rise, lift up and expand over the mountain range. This causes them to cool down, which causes an excess of moisture to condense into high clouds and results in heavy precipitation over the mountain range. This is known as
orographic rainfall and after this process, the air is dry because it has lost most of its moisture over the
Atlas Mountains. On the
leeward side, the cold, dry air starts to descend and to sink and compress, making the winds warm up. This warming causes the moisture to evaporate, making clouds disappear. This prevents rainfall formation and creates desert conditions in the Sahara. • Desert regions in the
Horn of Africa (
Ethiopia,
Eritrea,
Somalia and
Djibouti) such as the
Danakil Desert are all influenced by the air heating and drying produced by rain shadow effect of the
Ethiopian Highlands.
Southern Africa provide a rain shadow for the country's western portion. • The windward side of the island of
Madagascar, which sees easterly on-shore winds, is wet tropical, while the western and southern sides of the island lie in the rain shadow of the central highlands and are home to thorn forests and deserts. The drying effect of the central highlands extends into southeastern
Mozambique in spite of the
Mozambique Channel in between. The same is true for the island of
Réunion. • On
Tristan da Cunha,
Sandy Point on the east coast is warmer and drier than the rainy, windswept settlement of
Edinburgh of the Seven Seas in the west. • In
Western Cape Province, the
Breede River Valley and the
Karoo region lie in the rain shadow of the
Cape Fold Mountains and are arid; whereas the wettest parts of the Cape Mountains can receive ,
Worcester receives only around and is useful only for grazing.
Asia Central and Northern Asia • The
Himalayas and connecting ranges also contribute to arid conditions in
Central Asia including
Mongolia's
Gobi Desert, as well as the
semi-arid steppes of Mongolia and north-central to northwestern China.
Eastern Asia • The
Ordos Desert is rain shadowed by mountain chains including the Kara-naryn-ula, the Sheitenula, and the
Yin Mountains, which link on to the south end of the
Great Khingan Mountains. • The central region of
Myanmar is in the rain shadow of the
Arakan Mountains and is almost semi-arid with only of rain, versus up to on the
Rakhine State coast. • The plains around Tokyo, Japan – known as
Kantō Plain – during winter experiences significantly less precipitation than the rest of the country by virtue of surrounding mountain ranges, including the
Japanese Alps, blocking prevailing northwesterly winds originating in Siberia.
Southern Asia lie in a rain shadow, receiving far less rainfall. • The eastern side of the
Sahyadri ranges on the
Deccan Plateau including:
Vidarbha,
North Karnataka,
Rayalaseema and western
Tamil Nadu. •
Gilgit and
Chitral, Pakistan, are rainshadow areas. • The
Thar Desert is bounded and rain shadowed by the
Aravalli ranges to the southeast, the Himalaya to the northeast, and the Kirthar and Sulaiman ranges to the west. • The
Central Highlands of Sri Lanka rain shadow the northeastern parts of the island, which experience much less severe
summer monsoon rains and instead have precipitation peaks in autumn and winter.
Western Asia mountains in the north (just south of the
Caspian Sea), hence the country's mostly (semi) arid climate. to the west. • The peaks of the
Caucasus Mountains to the west and
Hindukush and
Pamir to the east rain shadow the
Karakum and
Kyzyl Kum deserts east of the
Caspian Sea, as well as the
semi-arid Kazakh Steppe. They also cause vast rainfall differences between coastal areas on the
Black Sea such as
Rize,
Batumi and
Sochi contrasted with the dry lowlands of
Azerbaijan facing the Caspian Sea. • The semi-arid
Anatolian Plateau is rain shadowed by mountain chains, including the
Pontic Mountains in the north and the
Taurus Mountains in the south. • The High Peaks of
Mount Lebanon rain-shadow the northern parts of the
Beqaa Valley and
Anti-Lebanon Mountains. • The
Judaean Desert, the
Dead Sea and the western slopes of the
Moab Mountains on the opposite (
Jordanian) side are rain-shadowed by the
Judaean Mountains. • The
Dasht-i-Lut in Iran is in the rain shadow of the
Elburz and
Zagros Mountains and is one of the most lifeless areas on Earth. • The peaks of the
Zagros Mountains rain-shadow the northern half of the
West Azerbaijan province in
Iranian Azerbaijan (above
Urmia), as manifested by the province's dry winters relative to those in the windward part of the region (i.e.
Kurdistan Region and
Hakkâri Province in Turkey). • Much of the
Mesaoria Plain of
Cyprus is in the rain shadow of the
Troodos Mountains and is semi-arid.
Europe Central Europe • The Plains of
Limagne and
Forez in the northern
Massif Central, France are also relatively rainshadowed (mostly the plain of Limagne, shadowed by the
Chaîne des Puys (up to 2000 mm; 80" of rain a year on the summits and below 600 mm; 20" at
Clermont-Ferrand, which is one of the driest places in the country). • The
Piedmont wine region of northern Italy is rainshadowed by the mountains that surround it on nearly every side:
Asti receives only of precipitation per year, making it one of the driest places in mainland Italy. • Some valleys in the inner
Alps are also strongly rainshadowed by the high surrounding mountains: the areas of
Gap and
Briançon in
France, the district of
Zernez in
Switzerland. • The
Kuyavia and the eastern part of the
Greater Poland has an average rainfall of about because of rainshadowing by the slopes of the
Kashubian Switzerland, making it one of the driest places in the
North European Plain.
Northern Europe • The
Pennines of Northern England, the mountains of
Wales, the
Lake District and the
Highlands of Scotland create a rain shadow that includes most of the eastern United Kingdom, due to the prevailing south-westerly winds.
Manchester and
Glasgow, for example, receive around double the rainfall of
Leeds and
Edinburgh respectively (although there are no mountains between Edinburgh and Glasgow). The contrast is even stronger further north, where
Aberdeen gets around a third of the rainfall of
Fort William or
Skye. In Devon, rainfall at
Princetown on Dartmoor is almost three times the amount received to the east at locations such as
Exeter and
Teignmouth.
The Fens of East Anglia receive similar rainfall amounts to
Seville. •
Iceland has plenty of
microclimates courtesy of the mountainous terrain.
Akureyri on a northerly
fiord receives about a third of the precipitation that the island of
Vestmannaeyjar off the south coast gets. The smaller island is in the pathway of
Gulf Stream rain fronts with mountains lining the southern coast of the mainland. • The
Scandinavian Mountains create a rain shadow for lowland areas east of the mountain chain and prevents the
Oceanic climate from penetrating further east; thus
Bergen and a place like
Brekke in
Sogn, west of the mountains, receive an annual precipitation of , respectively, while
Oslo receives only , and
Skjåk Municipality, a
municipality situated in a deep valley, receives only . Further east, the partial influence of the Scandinavian Mountains contribute to areas in east-central
Sweden around
Stockholm only receiving annually. In the north, the mountain range extending to the coast in around
Narvik and
Tromsø cause a lot higher precipitation there than in coastal areas further east facing north such as
Alta or inland areas like
Kiruna across the Swedish border. • The
South Swedish highlands, although not rising more than , reduce precipitation and increase summer temperatures on the eastern side. Combined with the high pressure of the
Baltic Sea, this leads to some of the driest climates in the humid zones of Northern Europe being found in the triangle between the coastal areas in the counties of
Kalmar,
Östergötland and
Södermanland along with the offshore island of
Gotland on the leeward side of the slopes. Coastal areas in this part of Sweden usually receive less precipitation than windward locations in
Andalusia in the south of Spain.
Southern Europe • The
Cantabrian Mountains form a sharp division between "
Green Spain" to the north and the dry central plateau. The northern-facing slopes receive heavy rainfall from the
Bay of Biscay, but the southern slopes are in rain shadow. The other most evident effect on the Iberian Peninsula occurs in the
Almería,
Murcia and
Alicante areas, each with an average rainfall of , which are the driest spots in Europe (see
Cabo de Gata) mostly a result of the mountain range running through their western side, which blocks the westerlies. • The
Norte Region in
Portugal has extreme differences in precipitation with values surpassing in the
Peneda-Gerês National Park to values close to in the
Douro Valley. Despite being only apart,
Chaves has less than half the precipitation of
Montalegre. • The eastern part of the
Pyrenees in the south of France (
Cerdagne). • In the Northern
Apennines of
Italy, Mediterranean city
La Spezia receives twice the rainfall of Adriatic city
Rimini on the eastern side. This is also extended to the southern end of the Apennines that see vast rainfall differences between
Naples with above on the Mediterranean side and
Bari with about on the Adriatic side. • The valley of the
Vardar River and south from
Skopje to
Athens is in the rain shadow of the
Accursed Mountains and
Pindus Mountains. On its windward side the Accursed Mountains has the highest rainfall in Europe at around with small glaciers even at mean annual temperatures well above , but the leeward side receives as little as .
Caribbean • Throughout the
Greater Antilles, the southwestern sides are in the rain shadow of the trade winds and can receive as little as per year as against over on the northeastern, windward sides and over over some highland areas. This is most apparent in
Cuba, where this phenomenon leads to the
Cuban cactus scrub ecoregion, and the island of
Hispaniola (which contains the Caribbean's highest mountain ranges), which results in xeric semi-arid shrublands throughout the
Dominican Republic and
Haiti.
North American mainland to the north and the
California Coast Ranges and the
Sierra Nevada to the south provide a significant rain-shadow for the inland
North American deserts. On the largest scale, the entirety of the North American
Interior Plains are shielded from the prevailing
Westerlies carrying moist Pacific weather by the
North American Cordillera. More pronounced effects are observed, however, in particular valley regions within the Cordillera, in the direct lee of specific mountain ranges. By contrast,
Aberdeen, which is situated southwest of the Olympics, receives nearly of rain per year • The east slopes of the Coast Ranges in central and southern California cut off the southern
San Joaquin Valley from enough precipitation to ensure desert-like conditions in areas around
Bakersfield. •
San Jose, and adjacent cities are usually drier than the rest of the
San Francisco Bay Area because of the rain shadow cast by the highest part of the
Santa Cruz Mountains. • The
Sonoran Desert is bounded to the west by the
Peninsular Ranges, but extends even along part of the east coast of the
Gulf of California. • The
Sierra Madre Occidental in Mexico are west of the
Chihuahuan Desert. Most rain shadows in the western
United States are due to the
Sierra Nevada mountains in California and
Cascade Mountains, mostly in
Oregon and
Washington. • The Cascades create a rain-shadowed
Columbia Basin area of
Eastern Washington and valleys in British Columbia, Canada - most notably the
Thompson and
Nicola Valleys which can receive less than of rain in parts, and the
Okanagan Valley (particularly the south, nearest to the US border) which receives anywhere from 12 to 17 inches of rain annually. • The
endorheic Great Basin of
Utah and
Nevada is in the rain shadows of the Cascades and Sierra Nevada. • The
Mojave Desert is rain-shadowed by the Sierra Nevada and the
Transverse Ranges of southern California. • The
Black Rock Desert is in the rain shadows of the Cascades and Sierra Nevada. • California's
Owens Valley is rain-shadowed by the Sierra Nevada. •
Death Valley in the United States, behind both the
Pacific Coast Ranges of
California and the
Sierra Nevada range, is the driest place in North America and one of the driest places on the planet. This is also due to its location well below
sea level which tends to cause high pressure and dry conditions to dominate due to the greater weight of the atmosphere above. The
Colorado Front Range is limited to precipitation that crosses over the
Continental Divide. While many locations west of the Divide may receive as much as of precipitation per year, some places on the eastern side, notably the cities of
Denver and
Pueblo, Colorado, typically receive only about 12 to 19 inches. Thus, the
Continental Divide acts as a barrier for precipitation. This effect applies only to storms traveling west-to-east. When low pressure systems skirt the
Rocky Mountains and approach from the south, they can generate high precipitation on the eastern side and little or none on the western slope. Further east: • The
Shenandoah Valley of Virginia, wedged between the
Ridge-and-Valley Appalachians and the
Blue Ridge Mountains and partially shielded from moisture from the west and southeast, is much drier than the very humid remainder of Virginia and the American Southeast. •
Asheville, North Carolina sits in the rain shadow of the
Balsam,
Smoky, and
Blue Ridge Mountains. While the mountains surrounding Asheville contain the
Appalachian temperate rainforests, with areas receiving over an annual average precipitation of , the city itself is the driest location in North Carolina, with an annual average precipitation of only . •
Ashcroft, British Columbia, the only true desert in Canada, sits in the rain shadow of the
Coast Mountains of Canada. •
Yellowknife, the capital and most populous city in the
Northwest Territories of
Canada, is located in the rain shadow of the mountain ranges to the west of the city.
Oceania Australia rain-shadowing the dry
Tablelands Region in Queensland (bottom-right). in New Zealand rain shadow the eastern side of the
South Island. • In
New South Wales and the
Australian Capital Territory,
Monaro is shielded by both the
Snowy Mountains to the northwest and coastal ranges to the southeast. Consequently, parts of it are as dry as the wheat-growing lands of those states. For comparison,
Cooma receives of rain annually, whereas
Batlow, on the western side of the ranges, receives of precipitation. Furthermore, Australia's capital
Canberra is also protected from the west by the
Brindabellas which create a strong rain shadow in Canberra's valleys, where it receives an annual rainfall of , compared to
Adjungbilly's . In the cool season, the
Great Dividing Range also
shields much of the southeast coast (i.e.
Sydney, the
Central Coast, the
Hunter Valley,
Illawarra, the
South Coast) from south-westerly
polar blasts that originate from the
Southern Ocean. • In
Queensland, the land west of
Atherton Tableland in the
Tablelands Region lies on a rain shadow and therefore would feature significantly lower annual rainfall averages than those in the
Cairns Region. For comparison,
Tully, which is on the eastern side of the tablelands, towards the coast, receives annual rainfall that exceeds , whereas
Mareeba, which lies on the rain shadow of the Atherton Tableland, receives of rainfall annually. • In
Tasmania, the central Midlands region is in a strong rain shadow and receives only about a fifth as much rainfall as the highlands to the west. • In
Victoria, the western side of
Port Phillip Bay is in the rain shadow of the
Otway Ranges. The area between
Geelong and
Werribee is the driest part of southern Victoria: the crest of the Otway Ranges receives of rain per year and has
myrtle beech rainforests much further west than anywhere else, while the area around
Little River receives as little as annually, which is as little as
Nhill or
Longreach and supports only grassland. Also in Victoria,
Omeo is shielded by the surrounding
Victorian Alps, where it receives around of annual rain, whereas other places nearby exceed . •
Western Australia's
Wheatbelt and
Great Southern regions are shielded by the
Darling Range to the west:
Mandurah, near the coast, receives about annually.
Dwellingup, inland and in the heart of the ranges, receives over a year while
Narrogin, further east, receives less than a year.
Pacific Islands •
Hawaii also has rain shadows, with some areas being desert.
Orographic lifting produces the world's second-highest annual precipitation record, , on the island of
Kauai; the leeward side is understandably rain-shadowed. The Argentinian wine region of Cuyo and Northern Patagonia is almost completely dependent on irrigation, using water drawn from the many rivers that drain glacial ice from the
Andes. • The
Guajira Peninsula in northern Colombia is in the rain shadow of the
Sierra Nevada de Santa Marta and despite its tropical latitude is almost arid, receiving almost no rainfall for seven to eight months of the year and being incapable of cultivation without irrigation. • The
Guianan savanna is in the rain shadow of the
Guiana Highlands and stands in stark contrast to the surrounding rainforest environment. == See also ==