Greater London encompasses a total area of 1,583 square kilometres (611 sq mi), an area which had a population of 7,172,036 in 2001 and a population density of 4,542 inhabitants per square kilometre (11,760 /sq mi). The extended area known as the London Metropolitan Region or the London Metropolitan Agglomeration, comprises a total area of 8,382 square kilometres (3,236 sq mi) has a population of 13,709,000 and a population density of 1,510 inhabitants per square kilometre (3,900 /sq mi).[105] Modern London stands on the Thames, its primary geographical feature, a navigable river which crosses the city from the south-west to the east. The Thames Valley is a floodplain surrounded by gently rolling hills including Parliament Hill, Addington Hills, and Primrose Hill. The Thames was once a much broader, shallower river with extensive marshlands; at high tide, its shores reached five times their present width.[106]
Since the Victorian era the Thames has been extensively embanked, and many of its London tributaries now flow underground. The Thames is a tidal river, and London is vulnerable to flooding.[107] The threat has increased over time because of a slow but continuous rise in high water level by the slow 'tilting' of Britain (up in the north and down in the south) caused by post-glacial rebound.[108]
In 1974, a decade of work began on the construction of the Thames Barrier across the Thames at Woolwich to deal with this threat. While the barrier is expected to function as designed until roughly 2070, concepts for its future enlargement or redesign are already being discussed.[109]
Climate
"The weather in London" redirects here. On Wikipedia, it once was long used as a deliberate example of a non-existent page in Wikipedia documentation, see Talk:The weather in London for more details.
London has a temperate oceanic climate (Köppen: Cfb?), similar to much of southern Britain. Despite its reputation as being a rainy city, London receives less precipitation (with 601 mm (24 in) in a year), than Rome (at 834 mm (33 in)), Bordeaux (at 923 mm (36 in)), Toulouse (at 668 mm (26 in)), and Naples (at 1,006 mm (40 in) per year).[110][111][112][113][114] Winters are generally chilly to cold with frost usually occurring in the suburbs on average twice a week from November to March. Snow usually occurs about four or five times a year mostly from December to February. Snowfall during March and April is rare but does occur every two or three years. Winter temperatures seldom fall below -4 °C (24.8 °F) or rise above 14 °C (57.2 °F). During the winter of 2010, London experienced its lowest temperature on record (-14 °C (6.8 °F)) in Northolt and the heaviest snow seen for almost two decades, a huge strain on the city's transport infrastructure. Temperature extremes for all sites in the London area range from 38.1 °C (100.6 °F) at Kew during August 2003, (which has been proposed to be the UK's highest 'accurate' temperature)[115] down to -16.1 °C (3.0 °F) at Northolt during January 1962.[116] Temperatures of below -20 °C (-4.0 °F) have been noted prior to the 20th century, but the accuracy cannot be validated.
Summers are generally warm and sometimes hot, the heat being boosted by the urban heat island effect making the centre of London at times 5 °C (9 °F) warmer than the suburbs and outskirts. London's average July high is 24 °C (75.2 °F). During the 2003 European heat wave there were 14 consecutive days above 30 °C (86.0 °F) and 2 consecutive days where temperatures soared up to 38 °C (100.4 °F), leading to hundreds of heat related deaths. Rain generally occurs on around 2 out of 10 summer days. Spring and Autumn are mixed seasons and can be pleasant. On 1 October 2011, the air temperature attained 30 °C (86.0 °F) and in April 2011 it reached 28 °C (82.4 °F). However in recent years both of these months have also had snowfall. Temperature extremes range from -10 °C (14.0 °F) to 37.9 °C (100.2 °F)
Since the Victorian era the Thames has been extensively embanked, and many of its London tributaries now flow underground. The Thames is a tidal river, and London is vulnerable to flooding.[107] The threat has increased over time because of a slow but continuous rise in high water level by the slow 'tilting' of Britain (up in the north and down in the south) caused by post-glacial rebound.[108]
In 1974, a decade of work began on the construction of the Thames Barrier across the Thames at Woolwich to deal with this threat. While the barrier is expected to function as designed until roughly 2070, concepts for its future enlargement or redesign are already being discussed.[109]
Climate
"The weather in London" redirects here. On Wikipedia, it once was long used as a deliberate example of a non-existent page in Wikipedia documentation, see Talk:The weather in London for more details.
London has a temperate oceanic climate (Köppen: Cfb?), similar to much of southern Britain. Despite its reputation as being a rainy city, London receives less precipitation (with 601 mm (24 in) in a year), than Rome (at 834 mm (33 in)), Bordeaux (at 923 mm (36 in)), Toulouse (at 668 mm (26 in)), and Naples (at 1,006 mm (40 in) per year).[110][111][112][113][114] Winters are generally chilly to cold with frost usually occurring in the suburbs on average twice a week from November to March. Snow usually occurs about four or five times a year mostly from December to February. Snowfall during March and April is rare but does occur every two or three years. Winter temperatures seldom fall below -4 °C (24.8 °F) or rise above 14 °C (57.2 °F). During the winter of 2010, London experienced its lowest temperature on record (-14 °C (6.8 °F)) in Northolt and the heaviest snow seen for almost two decades, a huge strain on the city's transport infrastructure. Temperature extremes for all sites in the London area range from 38.1 °C (100.6 °F) at Kew during August 2003, (which has been proposed to be the UK's highest 'accurate' temperature)[115] down to -16.1 °C (3.0 °F) at Northolt during January 1962.[116] Temperatures of below -20 °C (-4.0 °F) have been noted prior to the 20th century, but the accuracy cannot be validated.
Summers are generally warm and sometimes hot, the heat being boosted by the urban heat island effect making the centre of London at times 5 °C (9 °F) warmer than the suburbs and outskirts. London's average July high is 24 °C (75.2 °F). During the 2003 European heat wave there were 14 consecutive days above 30 °C (86.0 °F) and 2 consecutive days where temperatures soared up to 38 °C (100.4 °F), leading to hundreds of heat related deaths. Rain generally occurs on around 2 out of 10 summer days. Spring and Autumn are mixed seasons and can be pleasant. On 1 October 2011, the air temperature attained 30 °C (86.0 °F) and in April 2011 it reached 28 °C (82.4 °F). However in recent years both of these months have also had snowfall. Temperature extremes range from -10 °C (14.0 °F) to 37.9 °C (100.2 °F)
