Shanghai sits on the Yangtze River Delta on China’s eastern coast, and is roughly equidistant from Beijing and Hong Kong. The municipality as a whole consists of a peninsula between the Yangtze and Hangzhou Bay, China’s third largest island Chongming, and a number of smaller islands. It is bordered on the north and west by Jiangsu Province, on the south by Zhejiang Province, and on the east by the East China Sea. The city proper is bisected by the Huangpu River, a tributary of the Yangtze. The historic center of the city, the Puxi area, is located on the western side of the Huangpu, while a new financial district, Pudong, has developed on the eastern bank.
The vast majority of Shanghai’s 6,218 km2 (2,401 sq mi) land area is flat, apart from a few hills in the southwest corner, with an average elevation of 4 m (13 ft).[23] The city’s location on the flat alluvial plain has meant that new skyscrapers must be built with deep concrete piles to stop them sinking into the soft ground. The highest point is at the peak of Dajinshan Island at 103 m (340 ft).[24] The city has many rivers, canals, streams and lakes and is known for its rich water resources as part of the Taihu drainage area.

A park in the center of Shanghai
Public awareness of the environment is growing, and the city is investing in a number of environmental protection projects. A 10-year, US$1 billion cleanup of Suzhou Creek, which runs through the city center, was expected to be finished in 2008,[25] and the government also provides incentives for transportation companies to invest in LPG buses and taxis. Air pollution in Shanghai is low compared to other Chinese cities such as Beijing, but the rapid development over the past decades means it is still high on worldwide standards, comparable to Los Angeles.[26]
Shanghai has a humid subtropical climate (Koppen climate classification Cfa) and experiences four distinct seasons. In winter, cold northerly winds from Siberia can cause nighttime temperatures to drop below freezing, although most years there are only one or two days of snowfall. Summer in Shanghai is very warm and humid, with occasional downpours or freak thunderstorms. The city is also susceptible to typhoons, none of which in recent years has caused considerable damage.[27] The most pleasant seasons are Spring, although changeable, and Autumn, which is generally sunny and dry. Shanghai experiences on average 1,878 hours of sunshine per year, with the hottest temperature ever recorded at 40 °C (104 °F), and the lowest at −12 °C (10 °F).[28] The average number of rainy days is 112 per year, with the wettest month being June.[28] The average frost-free period is 276 days.[23]

New York City is located in the Northeastern United States, in southeastern New York State, approximately halfway between Washington, D.C. and Boston.[42] The location at the mouth of the Hudson River, which feeds into a naturally sheltered harbor and then into the Atlantic Ocean, has helped the city grow in significance as a trading city. Much of New York is built on the three islands of Manhattan, Staten Island, and Long Island, making land scarce and encouraging a high population density.

Satellite image showing the core of the New York metropolitan area. Over 10 million people live in the imaged area.
The Hudson River flows through the Hudson Valley into New York Bay. Between New York City and Troy, New York, the river is an estuary.[43] The Hudson separates the city from New Jersey. The East River, actually a tidal strait, flows from Long Island Sound and separates the Bronx and Manhattan from Long Island. The Harlem River, another tidal strait between the East and Hudson Rivers, separates Manhattan from the Bronx.
The city’s land has been altered considerably by human intervention, with substantial land reclamation along the waterfronts since Dutch colonial times. Reclamation is most notable in Lower Manhattan, with developments such as Battery Park City in the 1970s and 1980s.[44] Some of the natural variations in topography have been evened out, particularly in Manhattan.[45]
The city’s land area is estimated at 304.8 square miles (789 km2).[3][4] New York City’s total area is 468.9 square miles (1,214 km2). 164.1 square miles (425 km2) of this is water and 304.8 square miles (789 km2) is land. The highest point in the city is Todt Hill on Staten Island, which at 409.8 feet (124.9 m) above sea level is the highest point on the Eastern Seaboard south of Maine.[46] The summit of the ridge is largely covered in woodlands as part of the Staten Island Greenbelt.[47]
Climate
Under the Köppen climate classification, New York City has a humid subtropical climate and enjoys an average of 234 days with at least some sunshine annually.[48] It is the northernmost major city in North America that features a humid subtropical climate using the 0 °C (American scientist standard) isotherm as criteria.
Summers are typically hot and humid with average high temperatures of 79 – 84 °F (26 – 29 °C) and lows of 63 – 69 °F (17 – 21 °C), however temperatures exceed 90 °F (32 °C) on average of 16 – 19 days each summer and can exceed 100 °F (38 °C) every 4–6 years.[49] Winters are cold, and prevailing wind patterns that blow offshore somewhat minimizes the influence of the Atlantic Ocean. Yet, the Atlantic Ocean keeps the city warmer in the winter than inland North American cities located at similar latitudes such as Chicago, Pittsburgh and Cincinnati. The average temperature in January, New York City’s coldest month, is 32 °F (0 °C). However temperatures in winter could for few days be as low as 10s to 20s °F (−12 to −6 °C) and for a few days be as high as 50s or 60s °F (~10–15 °C).[50] Spring and autumn are erratic, and could range from chilly to warm, although they are usually pleasantly mild with low humidity.[51]
New York City receives 49.7 inches (1,260 mm) of precipitation annually, which is fairly spread throughout the year. Average winter snowfall is about 24.4 inches (62 cm), but this often varies considerably from year to year, and snow cover usually remains very short.[48] Hurricanes and tropical storms are rare in the New York area, but are not unheard of and always have the potential to strike the area.

Scope

Map of Central London
Greater London is the top-level administrative subdivision covering London. The small, ancient City of London at its core once contained the whole settlement, but as the urban area grew the City Corporation resisted attempts to amalgamate it with its suburbs, causing “London” to be defined in a number ways for different purposes; and the situation was once open to legal debate.[70] Forty percent of Greater London is covered by the London postal district, within which ‘LONDON’ forms part of postal addresses.[71][72]
The London telephone area code covers a larger area, similar in size to Greater London, although some outer districts are omitted and some places just outside are included. The area within the orbital M25 motorway is sometimes used to define the “London area”[73] and the Greater London boundary has been aligned to it in places.[74]
Outward urban expansion is now prevented by a metropolitan green belt,[75] although the built-up area extends beyond the boundary in places, resulting in a separately defined Greater London Urban Area. Beyond this is the vast London commuter belt.[76] Greater London is split for some purposes into Inner London and Outer London.[77] The city is split by the River Thames into North and South, with an informal Central London area in its interior. The coordinates of the nominal centre of London, traditionally considered to be the original Eleanor Cross at Charing Cross near the junction of Trafalgar Square and Whitehall, are approximately 51°30′29″N 00°07′29″W.[78]
Status
Within London, both the City of London and the City of Westminster have City status and both the City of London and the remainder of Greater London are the ceremonial counties.[79] The current area of Greater London has incorporated areas that were once part of the counties of Middlesex, Kent, Surrey, Essex and Hertfordshire.[80] London’s status as the capital of the England, and later the United Kingdom, has never been granted or confirmed officially—by statute or in written form.a
Its position was formed through constitutional convention, making its status as de facto capital a part of the UK’s unwritten constitution. The capital of England was moved to London from Winchester as the Palace of Westminster developed in the 12th and 13th centuries to become the permanent location of the royal court, and thus the political capital of the nation.[81] More recently, Greater London has been defined as a region of England and in this context known as London.[8]
Topography

West and central London seen from SPOT satellite
Greater London covers an area of 607 square miles (1,570 km2).[82] Its primary geographical feature is the Thames, 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.[83]
Since the Victorian era it 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.[84] The threat has increased over time due to 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.[85]
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.[86]
Climate
Main article: Climate of the United Kingdom
London has a temperate marine climate (Koppen climate classification Cfb), like much of the British Isles, so the city rarely sees extremely high or low temperatures. Summers are warm with average high temperatures of 21 °C (70 °F) – 24 °C (75 °F) and lows of 11 °C (52 °F) – 14 °C (57 °F). But temperatures can exceed 25 °C (77 °F) on many days, and in almost every year they exceed 30 °C (86 °F) on some days. The highest temperature ever recorded was 38 °C (100 °F) [87] on 10 August 2003.
Winters in London are chilly, but rarely below freezing with daytime highs around 5 °C (41 °F) – 8 °C (46 °F), while spring has mild days and cool evenings.[87] The lowest ever recorded temperature was −21.1 °C (−6 °F) in January 1795. Autumn is usually mild but often unsettled as colder air from the north and warmer air from the south meet. London is a relatively dry city with regular but generally light precipitation throughout the year, with an average of 583.6 millimetres (22.98 in) every year.
Snow is relatively uncommon, particularly because heat from the urban area can make London up to 5 °C (9 °F) warmer than the surrounding areas in winter. Some snowfall, however, is usually seen up to a few times a year. The snowfall of February 2009 was the heaviest London had seen for 18 years.

Hong Kong is located on China’s south coast, 60 km (37 mi) east of Macau on the opposite side of the Pearl River Delta. It is surrounded by the South China Sea on the east, south, and west, and borders the Guangdong city of Shenzhen to the north over the Shenzhen River. The territory’s 1,104 km² (426 sq mi) area consists of Hong Kong Island, the Kowloon Peninsula, the New Territories, and over 200 offshore islands, of which the largest is Lantau Island. Of the total area, 1,054 km² (407 sq mi) is land and 50 km² (19 sq mi) is inland water. In addition Hong Kong claims territorial waters to a distance of 3 nautical miles (5.6 km). The land area makes Hong Kong the179th largest habited territory in the world.^[3][8]

As much of Hong Kong’s terrain is hilly to mountainous with steep slopes, less than 25% of the territory’s landmass is developed, and about 40% of the remaining land area is reserved as country parks and nature reserves.^[53] Most of the territory’s urban development exists on Kowloon peninsula, along the northern edge of Hong Kong Island and in scattered settlements throughout the New Territories.^[54] The highest elevation in the territory is at Tai Mo Shan, at a height of 957 metres (3,140 ft) above sea level.^[55] Hong Kong’s long, irregular and curvaceous coast line provides it with many bays, rivers and beaches.^[56]

Despite Hong Kong’s reputation of being intensely urbanised, the territory has made much effort to promote a green environment,^[57] and recent growing public concern has prompted the severe restriction of further land reclamation from Victoria Harbour. Awareness of the environment is growing as Hong Kong suffers from increasing pollution compounded by its geography and tall buildings. Approximately 80% of the city’s smog originates from other parts of the Pearl River Delta.^[58]

Situated just south of the Tropic of Cancer, Hong Kong’s climate is humid subtropical climate (Köppen climate classification Cwa). Summer is hot and humid with occasional showers and thunderstorms, and warm air coming from the southwest. It is also the time when typhoons are most likely, sometimes resulting in flooding or landslides. Winter weather usually starts sunny and becomes cloudier towards February, with the occasional cold front bringing strong, cooling winds from the north. The most pleasant seasons are spring, although changeable, and autumn, which is generally sunny and dry.^[59] Hong Kong averages 1,948 hours of sunshine per year,^[60] while the highest and lowest ever recorded temperatures at the Hong Kong Observatory are 36.1 °C (97.0 °F) and 0.0 °C (32.0 °F), respectively.^[61]

Hong Kong