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Climate of the United Kingdom

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The current climate of the United=20 Kingdom is classified as temperate, with warm = summers, = cool winters = and=20 plentiful precipi= tation=20 throughout the year. The principle factors of influence on the climate = include=20 the UK's northerly latitude (which = ranges from 50=C2=B0=20 to 60=C2=B0 N), its close proximity to the Atlantic Ocean = and,=20 especially, the warming of the waters around the British Isles by = the Gulf=20 Stream. The weather can be notoriously changeable from one day to = the next=20 but temperature variations throughout the year are small.

The climate of the United Kingdom is significantly influenced by the = maritime=20 tropical, maritime=20 polar, continental=20 polar and continental=20 tropical air masses.

=20

A deep depression near Iceland on 27 October 2000

The UK is at the boundary of convergence between the warm tropical air to the = south and=20 the cold polar air to = the=20 north. In this area, the large temperature variation creates instability = and=20 this a major factor that influences the notoriously changeable and often = unsettled weather the UK experiences, where many or all types of weather = can be=20 experienced in a single day.

1 Seasons=20
- 1.1 Winter=20
- 1.2 Spring=20
- 1.3 Summer=20
- 1.4 Autumn=20
2 Regions=20
3 Sunshine and=20 cloud=20
4 The Atlantic=20 Ocean=20
5 Winds=20
6 Rainfall=20
7 Temperature=20
8 Severe = weather=20
9 Climate = history=20
10 Climate = change=20
11 See = also=20
12 External = links=20

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Seasons

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Winter

Winter in the UK is generally a cool, wet and windy season. = Temperatures at night = rarely drop=20 below -10 =C2=B0C and in = the=20 day rarely rise above 15 =C2=B0C. Precipitation is = plentiful=20 throughout the season with occasional snow.

Towards the later part of the season the weather usually stabilises = with less=20 wind, precipitation and lower temperatures. This change is particularly=20 pronounced near the coasts mainly due to the fact that the Atlantic is = often at its=20 coldest during this time after being cooled throughout the autumn and the winter. The early part = of winter=20 however is often unsettled and stormy; often the = wettest and=20 windiest time of the year.

Snow = can fall=20 occasionally and mainly affects northern and easterly areas and chiefly = higher=20 ground, especially the mountains of Scotland where the = amount of=20 lying snow may be significant enough on occasions to permit skiing at one of the = five Scottish=20 ski resorts. Snow however rarely lasts more than a week in most = areas as the=20 cold air brought by northerly or easterly winds, or sustained under high pressure = system,=20 gives way to mild southerly or westerly winds (normally introduced by North Atlantic = depressions). Low pressure systems move in from the Atlantic ocean=20 frequently throughout the season, often bringing strong winds and heavy = rain along = with mild=20 temperatures. However, on rare occasions some potent depressions may = move in=20 from the north in the form of 'Polar Lows', introducing heavy snow and = often blizzard-like=20 conditions to parts of the UK, particularly Scotland.

During periods of light winds and high pressure frost and fog can become a problem = and can=20 pose a major hazard for drivers on the roads.

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Spring

Spring is generally a rather calm, cold and dry season, = principally=20 since the Atlantic has lost much of its heat throughout the autumn and = winter.=20 However, as the sun rises higher in the sky and the days get longer,=20 temperatures can rise relatively high and thunderstorms / = heavy=20 showers can develop.

There is a fair chance of snow earlier in the season when it is = cooler.

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Summer

Summer climatic differences are more influenced by latitude = and=20 temperatures are highest in southern and central areas and lowest in the = north.=20 Generally, however, summer temperatures rarely go much above 30 =C2=B0C, = although=20 temperatures have soared as high as 38 =C2=B0C.

The north west and north east has cool summers, the south west has = rather=20 warmer summers (average 17 =C2=B0C) and the south and south east have = the warmest=20 summers.

Summer is a rather dry season on average but rainfall totals can = have a wide=20 local variation due to localised thunderstorms. These thunderstorms = mainly occur=20 in southern, eastern and central areas and are less frequent and severe = in the=20 north and west.

North Atlantic depressions are not as frequent or severe in summer = but=20 increase both in severity and frequency towards the end of the season.

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Autumn

Autumn in the UK is notorious for being extremely unsettled. = As cool=20 polar air moves southwards following the sun in the sky, it meets the warm air = of the tropics and=20 produces an area of great disturbance along which the United Kingdom = lies. This=20 combined with the warm ocean, which due to = heating=20 throughout the spring and summer, produces the unsettled weather of = autumn. In=20 addition, when the air is particularly cold it may actually be colder = than the=20 ocean and this can result in significant amounts of condensation, = producing clouds = which=20 eventually condense and bring rain to the UK.

Atlantic depressions during this time can become intense and = sustained winds=20 of hurricane force = (greater than=20 74 mph) have been reported. One such intense depression was the great=20 =E2=80=9Churricane=E2=80=9D of 1987. (see below)

Western areas, being closest to the Atlantic, experience these severe = conditions to a significantly greater extent than eastern areas.

As such, autumn, particularly the latter part, is often the stormiest = time of=20 the year.

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Regions

Regional climatic differences in the United Kingdom are dominated by = the=20 Atlantic Ocean. The western side of the United Kingdom is, being closest = to the=20 Atlantic, generally the mildest, wettest and windiest region of the UK. = As its=20 temperatures are most under the moderating effect of the Atlantic, = temperature=20 variations here are seldom extreme.

Eastern areas are by contrast drier, cooler, less windy and also = experience=20 the greatest daily and seasonal temperature variations.

The various regions of the UK are under the influence of the various = air = masses to=20 varying degrees:-

The northeast is most under the influence of the continental=20 polar air mass, which brings cold dry air.

The south and southeast is most under the influence of the = continental tropical=20 air mass, which brings warm, dry air.

The south west is most under the influence of the maritime=20 tropical air mass, which brings warm moist air.

The north west is most under the influence of the maritime=20 polar air mass, which brings cool moist air.

The proximity of a place to these air masses greatly determines the = climate=20 of it.

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Sunshine and cloud

The average annual amount of sunshine for the = United Kingdom=20 is relatively low and around 2/3 of days are partly cloudy, occasionly = with=20 little sun at all. Southern coasts, however, often have the clearest = skies=20 because cumulus cloud = formation=20 generally takes place over land, so coastal areas are = often cloud=20 free. These south coast counties of Dorset, Hampshire and Sussex have annual = average totals=20 of between 1,750 and 2000 hours of sunshine a year. Western and mountainous=20 areas are generally the cloudiest areas of the UK, with some mountainous = areas=20 receiving less than 1,000 hours of sunshine a year.

= =20

A fine summer's day

Valley areas=20 such as the Welsh=20 valleys, due to their north-south orientation, often receive less = sunshine=20 than flat areas because the hills/mountains on either side of the valley = obscure=20 the sun in the early morning and late evening.

On occasions blocking anticyclones (high pressure=20 systems) may move over or near the UK and may persist for weeks or = even=20 months. The cool dry air often results in clear skies and few clouds, = bringing=20 frosty = nights in=20 winter and hot days in the summer.

The mountains of the UK can be especially cloudy with extensive mist and fog. Near the coast, sea=20 fog may move in during winter nights and fog in other areas of the = UK can=20 persist for hours or even days in the winter and can pose a major hazard = for=20 drivers and aircraft.

Average annual daily hours of sunshine range from between one and = three hours=20 in midwinter to between five and eight in midsummer.

Most sunshine in one month: 383.9 hours at Eastbourne (East=20 Sussex) in July=20 1911.

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The Atlantic Ocean

One of the most important influences on the British climate is the = Atlantic=20 Ocean and especially the North = Atlantic=20 current which brings warm waters from the Gulf of Mexico = to the=20 United Kingdom by means of the global = conveyor.

This has a powerful moderating and warming effect on the UK climate. = The=20 North Atlantic Drift warms the climate of the UK to such a great extent = that=20 temperatures in winter would be about 10 =C2=B0C lower than they are = today if it=20 didn't exist and means that England can have vineyards where Canada has polar bears.

These warm ocean currents = bring=20 substantial amounts of humidity with them = and=20 contributes strongly to the notoriously wet climate the UK = experiences.

Depressions= are=20 another major product of the Atlantic Ocean and roll in towards the UK=20 throughout the year and are especially intense and frequent in autumn = and=20 winter. These depressions can be very severe and often bring in heavy = rain and=20 strong winds.

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Winds

A high temperate latitude = and close=20 proximity to a large ocean on its westerly side means that the United = Kingdom is=20 a windy place.

The prevailing wind in the United Kingdom is from the south west but = in such=20 a changeable climate it may blow from any direction for sustained = periods of=20 time. Winds are strongest near westerly facing coasts and inland areas = where=20 there is little topography, such as = mountains, to=20 divert the wind.

Gales = (which are=20 defined as winds with speeds of 32 to 63 miles per hour) are strongly = associated=20 with the passage of deep depressions across or close to the United = Kingdom, and=20 both are most frequent in the winter. The Hebrides experience = on average=20 35 days=20 of gale a year (a day where there are gale force winds) while more = inland=20 areas in England receive less than 5 days of gale a year.

Areas of high elevation tend to = have higher=20 wind speeds than low elevations, and Great Dun Fell = in Cumbria (at 857=20 meters) averaged 114 days of gale a year during the period 1963 to 1976.

Highest gust=20 recorded at a low level: 103 knots (118 mph, 191 km/h) at Gwennap=20 Head (Cornwall) on 15=20 December 1979.

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Rainfall

Parts of the United Kingdom are surprisingly dry - London receives less rain = annually than Rome, Sydney or New York. In England = it=20 typically rains on about 1 day in 4 and slightly more in winter. The = wettest=20 seasons are the winter and autumn.

Rainfall amounts can vary greatly across the United Kingdom and = generally the=20 further west and the higher the elevation, the greater the rainfall. The = Lake=20 District is one of the wettest places in the UK with an average = annual=20 rainfall total that exceeds 2000 mm. The mountains of Wales, Scotland, the pennines and the=20 moors of the = south west=20 are also particularly wet. In contrast, the south, south east, east and = the=20 southern midlands receive less than 700 mm of rain per year.

The county of Essex is one of = the=20 driest in the British Isles, = with an=20 average annual rainfall of around 600 mm (24 inches), although it = typically=20 rains on around 90 days per year. In some years rainfall in Essex can be = below=20 450 mm (18 inches) =E2=80=94 less than the average annual rainfall in Jerusalem and Beirut.

The main reasons for high number of rainy days in the UK are its mid-latitude=20 position, its close proximity to the Atlantic ocean and the warm waters = the=20 North Atlantic Drift brings.

Most rainfall in the UK comes from North Atlantic depressions which = roll into=20 the UK throughout the year and are particularly frequent and intense in = the=20 autumn and winter. They can on occasions bring prolonged periods of = heavy rain=20 in the north and flooding is not = rare.

Precipitation over the mountains of the north is especially high and = are some=20 of the wettest places in Europe with an average annual rainfall = exceeding 60 inches = (1,500 mm).

Eastern and southern areas, away from the ocean, are considerably = drier than=20 western and northern areas.

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Temperature

Generally the UK has mild to cool winters and warm to hot summers = with little=20 variation in temperature throughout the year. In England the average = annual=20 temperature varies from 8.5 =C2=B0C in the north to 12 =C2=B0C in the = south, but over the=20 higher ground this can be several degrees lower. This small variation in = temperature is to a large extent due to the moderating effect the = Atlantic ocean=20 has since water has a much greater heat capacity than air and tends to = release=20 it slowly throughout the year. This has a warming influence on coastal = areas in=20 winter and a cooling influence in summer.

The ocean is at its coldest in February or early March, = thus around=20 coastal areas February is often the coldest month, but inland there is = little to=20 choose between February and January as the coldest.

Temperatures tend to drop lowest in late winter nights inland, in the = presence of high pressure, clear skies, light winds and when there is = snow on=20 the ground. On occasions, cold polar or continental air can be drawn in = over the=20 United Kingdom to bring very cold weather.

The floors of inland valleys away from = warming=20 influence of the sea can be particularly cold as cold air, being denser = than=20 warm air, tends to drain into them. A temperature of -26.1 =C2=B0C was = recorded under=20 such conditions at Edgmond in = Shropshire=20 on 10=20 January 1982, the=20 coldest temperature recorded in England and = Wales. The=20 following day the coldest maximum temperature in England, at -11.3 = =C2=B0C, was=20 recorded at the same site.

The warmest winter temperatures tend to occur on the lee of high = ground and=20 by the coast and are produced when a moist south or south = west wind=20 warms up downwind after the crossing the mountains. Temperatures in = these areas=20 can rise as high as 18 =C2=B0C in winter on rare occasions.

July = tends to be=20 the warmest month and the highest temperatures tend to occur away from = the=20 Atlantic in south eastern and central areas where summer temperatures = can rise=20 as high as 34 =C2=B0C. It soared to 38.1 =C2=B0C in Kent in the summer of = 2003, the=20 highest temperature ever recored in the United Kingdom.

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Severe weather

While the UK isn't particularly noted for extreme = weather, it does=20 occur, and conditions have been known reach extreme levels on occasions. = In the=20 winter of 1982 for=20 example, for a few days parts of central and southern England = experienced=20 temperatures lower than central Europe = and Moscow. = In contrast,=20 the summers of 1975 and 1976 experienced temperatures as high as 34 to = 35 =C2=B0C. It=20 was so dry the country suffered drought and water shortages.

Extended periods of extreme weather, such as the drought of 1975-1976 = and the=20 very cold winters of 1962-1963 and 1982-1983, are often caused by = blocking anti-cyclones = which can=20 persist several days or even weeks. In winter they can bring long = periods of=20 cold dry weather and in summer long periods of hot dry weather.

There have also been occurrences of severe flash floods = caused by=20 intense rainfall, the worst of which was the Lynmouth = disaster of=20 1952 in = which 34=20 people died and some 38 houses and buildings were completely destroyed. = Recently=20 in the summer of 2004, a severe flash flood devastated the town of Boscastle in=20 Cornwall.=20 However, the worst floods in the United Kingdom in modern times occurred = in 1953. = A powerful=20 storm from the Atlantic moved around Scotland and then down the east = coast of=20 England. As it moved south it produced a storm surge which = was=20 magnified as the North Sea became = narrower the=20 further south the storm moved. By the time the storm affected south-east = England=20 and Holland the=20 surge had reached heights of 12 feet. Over 300 people were killed by the = floods=20 in eastern England.

Thunderstorms are = most=20 common in the south and eastern inland areas, and least common in the = north and=20 west. As a result of this, south and eastern inland areas tend to have = their=20 wettest months in the summer while western, northern and eastern coasts = are most=20 likely to have their driest month in the spring and their wettest in = late=20 autumn. At London=20 and Birmingham for = example,=20 thunderstorms occur on average about 15 days a year, while in the north = in west=20 it is more like 8 days a year.

Strong winds occur mainly in the autumn and winter months associated = with low=20 pressure systems. The "Great" storm = of=20 1987 (23 fatalities) and the Burns' Day = storm of 1990 (97 = fatalities) are=20 particularly severe examples.

Relative to its land area, the United Kingdom has more reported tornados than any=20 other country (around 33 per year), excluding the Netherlands, = although most=20 are minor.

The most rain to fall on a single day was 279 mm at Martinstown=20 (Dorset) on 18=20 July 1955.

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Climate history

The climate of the United Kingdom has not always been the way it is = today,=20 and in some periods it was much warmer, and in others it was much = colder. One of=20 the greatest climatic events the UK has experienced was the Ice Age. This was a = period of=20 extreme cold weather that lasted for tens of thousands of years and = ended about=20 10,000 years ago. During this period the temperature was so extremely = low that=20 the much of the surrounding ocean froze and a great ice sheet extended = over all=20 but the very southern edge of the UK.

10,000 years ago the UK began warming, resulting in the melting of = the ice=20 sheets bringing the interglacial = period that=20 were are in today. There have been many glacial and = interglacial periods=20 in the geological history of the United Kingdom.

The temperature records in England are continuous back to the mid 17th=20 century. The most quoted record is the Central= England=20 temperature (CET) record which is an compound source of = cross-correlated=20 records from several locations in central England.

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Climate change

Some evidence exists that suggests that the climate of the United = Kingdom is=20 undergoing a process of warming as a result of global climate = change.

Current research has concluded that the north of the UK is warming = faster=20 than the south and this process is expected to continue in the future = unless=20 global emissions of greenhouse = gases, the=20 prime culprit for global warming, = are=20 reduced. Average annual temperatures are expected to rise by about 2 and = 3.5 =C2=B0C=20 by the 2080s and the=20 autumn and winter will see the greatest warming, with summer rises of=20 temperature in south England and south Wales expected to be the = highest.

Rises in temperature in the winter of the northwest of Scotland are = predicted=20 to be between 1 =C2=B0C and 2 =C2=B0C. The south east of the United = Kingdom will=20 experience some of the most dramatic changes in temperature with an = increase of=20 4 or 5 =C2=B0C expected by the 2080s.

Precipitation is expected to increase in all areas of the United = Kingdom with=20 increases of 15% to 35%, depending on the area of the country. Summers = will=20 become drier and the country as a whole may be anything from 35% to 50% = drier by=20 the 2080s with the largest changes expected in the south east of england = and the=20 smallest in the north west of Scotland.

Snow = will become=20 up to 60% more rare in parts of Scotland and up to 90% more rare in the = rest of=20 the UK.

It is expected that due to this warming severe weather events in the = UK will=20 become more frequent and severe and rising sea = levels from=20 melting ice=20 caps could flood parts of low lying = areas of=20 the UK such as London.

The summer of 2003=20 was one of the hottest on record, with a temperature of 38.1 =C2=B0C = being recorded=20 in Gravesend, Kent -=20 the highest ever measured in the UK. Some point to this as evidence of = global=20 warming.

There is a small possibility that northern Europe is faced with a = period of=20 cold due to a Shutdown=20 of the Thermohaline circulation.

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External links

Retrieved from "http:= //en.wikipedia.org/wiki/Climate_of_the_United_Kingdom"

Category:=20 Climate=20 of the United Kingdom

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Climate of the United Kingdom

From Wikipedia, the free encyclopedia

Contents

Seasons

Winter

Spring

Summer

Autumn

Regions

Sunshine and cloud

The Atlantic Ocean

Winds

Rainfall

Temperature

Severe weather

Climate history

Climate change

See also

External links

Views

Personal tools

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