Climate of the British Isles
Encyclopedia
British Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...
are an archipelago off the north-west of Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, consisting of the islands of Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
and Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
along with smaller surrounding ones. Its position allows dry continental air from Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
to meet wetter air from the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, which causes the weather to be highly variable, often changing many times during the day. It is defined as a temperate oceanic climate, or Cfb on the Köppen climate classification system. It is significantly warmer than other regions on the same latitude, due to the warmth provided by the Gulf Stream
Gulf Stream
The Gulf Stream, together with its northern extension towards Europe, the North Atlantic Drift, is a powerful, warm, and swift Atlantic ocean current that originates at the tip of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean...
. Temperatures do not often switch between great extremes, with warm summers and mild winters.
Temperature
The British Isles undergo very small temperature variations. This is due to its proximity to the Atlantic, which acts as a temperature buffer, warming the Isles in winter and cooling them in summer. Coastal areas tend to be more temperature than inland areas, as the influence of the ocean is less acute. Valleys can be especially cold, as cool air collects in them during the winter. July is usually the warmest month, with the highest temperatures being found closest to Continental EuropeContinental Europe
Continental Europe, also referred to as mainland Europe or simply the Continent, is the continent of Europe, explicitly excluding European islands....
, in south-east England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. Temperatures usually do not reach freezing points, especially in coastal areas.
Sunshine and cloud
Radiation fog may develop over inland areas of Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
and can persist for hours or even days in the winter and can pose a major hazard for drivers and aircraft. Fog is more common inland and on higher altitudes; mainly during winter and during the morning at times of high pressure.
On occasions blocking anticyclones (high pressure systems
High pressure area
A high-pressure area is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. Winds within high-pressure areas flow outward due to the higher density air near their center and friction with land...
) may move over the British Isles, which can persist for weeks or even months. The subsided, dry air often results in clear skies and few clouds, bringing frost
Frost
Frost is the solid deposition of water vapor from saturated air. It is formed when solid surfaces are cooled to below the dew point of the adjacent air as well as below the freezing point of water. Frost crystals' size differ depending on time and water vapour available. Frost is also usually...
y nights in winter and hot days in the summer, when some coastal areas can achieve almost maximum possible sunshine for periods of weeks.
Precipitation
Rainfall varies across the Isles, with a general trend to more rain as you go west and in higher elevations. December and January are usually the wettest months. The mountain rangeMountain range
A mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...
s are the wettest areas in the Isles. These are some of the wettest locations in Europe. Most rainfall comes from North Atlantic depressions occur throughout the year and are particularly frequent and intense in the autumn and winter. They can on occasions bring prolonged periods of heavy rain, and flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
ing is quite common.
Snow
Snow
Snow is a form of precipitation within the Earth's atmosphere in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by...
can occur during winter months, but is rare. Hail
Hail
Hail is a form of solid precipitation. It consists of balls or irregular lumps of ice, each of which is referred to as a hail stone. Hail stones on Earth consist mostly of water ice and measure between and in diameter, with the larger stones coming from severe thunderstorms...
, although uncommon, can happen any time throughout the year.
Winds
The prevailing winds over the British Isles are from the south-west, and winds are strongest on coasts that face the Atlantic. Generally, the coast tends to be windier than inland areas; and the west tends to be windier than the east.Gale
Gale
A gale is a very strong wind. There are conflicting definitions of how strong a wind must be to be considered a gale. The U.S. government's National Weather Service defines a gale as 34–47 knots of sustained surface winds. Forecasters typically issue gale warnings when winds of this strength are...
s — which are defined as winds with speeds of 51 to 101 km/h (31.7 to 62.8 mph)— are strongly associated with the passage of deep depressions across the area. The Hebrides
Hebrides
The Hebrides comprise a widespread and diverse archipelago off the west coast of Scotland. There are two main groups: the Inner and Outer Hebrides. These islands have a long history of occupation dating back to the Mesolithic and the culture of the residents has been affected by the successive...
experience on average 35 days of gale a year (a day where there are gale force winds). Areas of high elevation
Elevation
The elevation of a geographic location is its height above a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface ....
tend to have higher wind speeds than low elevations.
Severe weather
The British Isles do not experience extreme weatherExtreme weather
Extreme weather includes weather phenomena that are at the extremes of the historical distribution, especially severe or unseasonal weather. The most commonly used definition of extreme weather is based on an event's climatological distribution. Extreme weather occurs only 5% or less of the time...
regularly. There have been several occasions where extreme weather events have occurred. In the winter of 1982, for a few days parts of central and southern England experienced temperatures lower than central Europe
Central Europe
Central Europe or alternatively Middle Europe is a region of the European continent lying between the variously defined areas of Eastern and Western Europe...
and Moscow
Moscow
Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...
. In contrast, the summers of 1975 and 1976 experienced temperatures as high as 35 °C (95 °F). It was so dry the country suffered drought and water shortages. Extended periods of extreme weather, such as the drought of 1975–1976 and the very cold winters of 1946–1947, 1962–1963, 1978–79, 1981–1982 and 2009–2010, are often caused by blocking anti-cyclones which can persist several days or even weeks. In winter they can bring long periods of cold dry weather and in summer long periods of hot dry weather.
Cyclones
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
s themselves do not affect the British Isles due to the cold temperature of the surrounding Ocean. Any Tropical cyclone
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
that comes near the Isles has said to have undergone a process called extratropical transition. The Isles do experience these extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
s, The Great Storm of 1987
Great Storm of 1987
The Great Storm of 1987 occurred on the night of 15/16 October 1987, when an unusually strong weather system caused winds to hit much of southern England and northern France...
was a very deep depression which formed in the Bay of Biscay
Bay of Biscay
The Bay of Biscay is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Brest south to the Spanish border, and the northern coast of Spain west to Cape Ortegal, and is named in English after the province of Biscay, in the Spanish...
, which also contained the remnants of Hurricane Floyd
Hurricane Floyd (1987)
Hurricane Floyd was the only hurricane to make landfall in the United States in the 1987 Atlantic hurricane season. The final of seven tropical storms and three hurricanes, Floyd developed on October 9 just off the east coast of Nicaragua. After becoming a tropical storm, it moved northward...
. Hurricane Lili
Hurricane Lili (1996)
Hurricane Lili was a relatively long-lived hurricane during the very active 1996 Atlantic hurricane season. Lili formed on October 14 from a tropical wave, which emerged from the coast of west Africa on October 4. The tropical wave which developed into Lili was slow to form due to unfavorable wind...
of 1996 and Hurricane Gordon
Hurricane Gordon (2006)
Hurricane Gordon was the first tropical cyclone since 1992 to affect the Azores while retaining tropical characteristics. The eighth tropical storm, third hurricane, and first major hurricane of the 2006 Atlantic hurricane season, Gordon formed on September 10 in the tropical Atlantic Ocean...
of 2006 both were strong extratropical cyclones with tropical storm-force winds, which caused transport closures, power-cuts and flooding.
Flash floods
There have also been occurrences of severe flash floods caused by intense rainfall. The most severe was the Lynmouth disaster of 1952 in which 34 people died and 38 houses and buildings were completely destroyed. In the summer of 2004, a severe flash flood devastated the village of BoscastleBoscastle
Boscastle is a village and fishing port on the north coast of Cornwall, England, in the civil parish of Forrabury and Minster. It is situated 14 miles south of Bude and 5 miles north-east of Tintagel....
in Cornwall
Cornwall
Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...
. However, the worst floods occurred in the North Sea flood of 1953
North Sea flood of 1953
The 1953 North Sea flood was a major flood caused by a heavy storm, that occurred on the night of Saturday 31 January 1953 and morning of 1 February 1953. The floods struck the Netherlands, Belgium, England and Scotland.A combination of a high spring tide and a severe European windstorm caused a...
. A powerful storm from the Atlantic moved around Scotland and down the east coast of England. As it moved south it produced a storm surge
Storm surge
A storm surge is an offshore rise of water associated with a low pressure weather system, typically tropical cyclones and strong extratropical cyclones. Storm surges are caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea...
which was magnified as the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
became narrower further south. By the time the storm affected south-east England and the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
, the surge had reached the height of 3.6 metres (12 ft). Over 300 people were killed by the floods in eastern England.
Thunderstorms
ThunderstormThunderstorm
A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically assigned cloud type associated with the...
s are most common in the south-east, and least common in the north-west. Occasionally, thunderstorms can be severe and produce large hail
Hail
Hail is a form of solid precipitation. It consists of balls or irregular lumps of ice, each of which is referred to as a hail stone. Hail stones on Earth consist mostly of water ice and measure between and in diameter, with the larger stones coming from severe thunderstorms...
stones as seen in Ottery St Mary
Ottery St Mary
Ottery St Mary, known as "Ottery" , is a town in the East Devon district of Devon, England, on the River Otter, about ten miles east of Exeter on the B3174. It is part of a large civil parish of the same name, which also covers the villages of West Hill, Metcombe, Fairmile, Alfington, Tipton St...
, Devon
Devon
Devon is a large county in southwestern England. The county is sometimes referred to as Devonshire, although the term is rarely used inside the county itself as the county has never been officially "shired", it often indicates a traditional or historical context.The county shares borders with...
in October 2008, where drifts reached 1.8 metres (5.9 ft).
Climate change
Estimates produced by the Met OfficeMet Office
The Met Office , is the United Kingdom's national weather service, and a trading fund of the Department for Business, Innovation and Skills...
predict average annual temperature to increase by 2°C (4°F) and the warmest summer day to increase by 3°C (6°F) by the 2050s. Average winter rainfall is also likely to increase and most areas will see a slight decrease in annual rainfall.
Recent events
Recently the British Isles have undergone some record breaking events. In 2004-2006, a partial drought caused fires to break out throughout the south of Great Britain, and water restrictions were introduced in some areas. The drought problems were solved due to the unusually wet period between October 2006 and July 2007, which had higher than average rainfall.The year 2006 was an unusually warm one. Although the year started off cool, from April the weather stayed warmer than average. July was the hottest month on record for the Isles and most of Europe,
History
The last glacial period in the British Isles ended about 10,000 years ago. During this period the temperature was so low that much of the surrounding ocean froze and an ice sheetIce sheet
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² , thus also known as continental glacier...
extended across most of the Isles.
The cold period from the 16th century to the mid-19th century is known as the Little Ice Age
Little Ice Age
The Little Ice Age was a period of cooling that occurred after the Medieval Warm Period . While not a true ice age, the term was introduced into the scientific literature by François E. Matthes in 1939...
.
The temperature records in England are continuous back to the mid 17th century. The Central England temperature
Central England temperature
The Central England Temperature record was originally published by Professor Gordon Manley in 1953 and subsequently extended and updated in 1974, following many decades of painstaking work...
(CET) record is the oldest in the world, and is a compound source of cross-correlated records from several locations in central England.