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The geography of the city of Toronto, Canada, covers an area of and is bounded by Lake Ontario to the south, Etobicoke Creek and Highway 427 to the west, Steeles Avenue to the north, and the Rouge River to the east. In addition to Etobicoke Creek and the Rouge River, the city is trisected by two minor rivers and their tributaries, the Humber River in the west end and the Don River east of downtown. Both flow southward to Lake Ontario at Humber Bay and Toronto Harbour respectively, which are part of the longer Waterfront. The concentration and protection of Toronto's ravines allows for large tracts of densely forested valleys with recreational trails within the city. 17.5% of Toronto is covered with trees,〔(Trees on Private Property )〕 a fairly high percentage within a large city in North America and there are ambitious proposals to double the coverage. The shoreline of the former Lake Iroquois is a major west−east geological feature which was formed at the end of the last glacial period. In the west end, Davenport Road follows the ancient shoreline with the steps to Casa Loma rising above and downtown skyscrapers clearly visible to the southeast. It merges with current Lake Ontario shoreline at the Scarborough Bluffs promontory. Toronto's immediate neighbours are Mississauga and Brampton within the Regional Municipality of Peel, Vaughan and Markham within the Regional Municipality of York, and Pickering within the Regional Municipality of Durham. The Greater Toronto Area (GTA) includes the regional municipalities of Halton, Peel, York and Durham. The GTA is part of a larger, natural ecosystem known as the Greater Toronto Bioregion. This ecosystem is bounded by Lake Ontario, the Niagara Escarpment, and the Oak Ridges Moraine, and includes many watersheds that drain into Lake Ontario. Some parts of Toronto, such as High Park and the lower Humber River are located in the most northern parts of the Carolinian forest zone found in North America. In March 2005, the Government of Ontario unveiled the boundaries of a greenbelt around the Greater Toronto Area, a area stretching from Niagara Falls to Peterborough. The green belt is designed to curb urban sprawl and to preserve valuable natural areas and farmland surrounding the city. However, some types of development including detached single residential, quarries and commercial facilities continue to get approved, exerting pressure and population growth on the Greenbelt. Toronto is the latest in a line of cities that have implemented growth boundaries of some kind as a method of restricting urban growth, including Ottawa, Portland, Oregon, Frankfurt, Melbourne, Seoul and London, UK. ==Climate== Toronto's continental climate is moderated by Lake Ontario; its climate is among the mildest in Canada east of the Rocky Mountains. Downtown Toronto sits in a pocket of the humid continental climate (Köppen climate classification Dfa) zone found at the south-western end of Lake Ontario covering the southern part of the city – including downtown, where the annual average temperature exceeds . It is located in hardiness zone 7a. There is a high degree of variability from year to year and sometimes even over a period of days, particularly during the winter months. Lake Ontario's water temperature varies due to upwelling of colder water or warmer pools of surface water creating very localized thermal contrast; the deeper waters of the lake, far from the shore, remain at a near constant water temperature of , the effect of which is either cooling or warming (in winter). This creates generally warmer nights through the colder season. When offshore winds occur in summer, they warm as they blow toward the lakeshore in the evening; conversely, the cooling effect by the lake is most pronounced on spring afternoons, which affects Toronto even more than other cities on the Great Lakes as during spring onshore east to southeast winds are predominant, on some days the temperatures can be as much as 10C cooler than areas located far enough away from the Lake Ontario, an effect that wanes by summer when the dominant windflow becomes more southwesterly. Springs and autumns feature varied weather with alternating periods of dry, sunny weather and rain. These seasons are brief when compared to summer or winter seasons, many days in thse seasons are sunny with pleasant rather than warm or cold temperatures. Nights are generally cool, but frosts are rare. Snow can fall in early spring or late fall but usually melts quickly after contact with the ground. At these times changeable times of the year, temperature contrasts (up to in extreme cases) can occur within a short time frame due to rapidly changing air masses that sweep across the continent, Toronto's weather is affected by the relative position of the polar jet stream and storm track, both of which pass over the area with some frequency. Annual average precipitation is . 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Geography of Toronto」の詳細全文を読む スポンサード リンク
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