“Geography of Alberta”的意思、由来-开放百科全书

Alberta is a Canadian province. Located in Western Canada, the province has an area of {{convert|661190|km2|sqmi}} and is bounded to the south by the U.S. state of Montana along 49° north for {{convert|298|km|mi}}; to the east at 110° west by the province of Saskatchewan for {{convert|1223|km|mi}}; and at 60° north the Northwest Territories for {{convert|644|km|mi}}. The southern half of the province borders British Columbia along the Continental Divide of the Americas on the peaks of the Rocky Mountains, while the northern half borders British Columbia along the 120th meridian west.

Terrain

Alberta is a fertile province, as the southern portion of its surface consists chiefly of plains that are almost entirely treeless. As the slopes of the Rocky Mountains to the west are reached, more trees are found until in the foothills of the mountains, bodies of forest timber occur. Trees also become more numerous in the northern part of the province, until in the region north of the North Saskatchewan River continuous forests are met with again. From the southern boundary line for 2.5° north the prairie is dry, but of good soil, which grows excellent crops when irrigated. North of this region, the surface of the province is of the most fertile soil, with ordinary rainfall sufficing for agriculture. Alberta also has large oil reserves, especially in the Athabasca Oil Sands in the north of the province.

The appearance of the prairie section of the province is that of undulating grasslands, with rounded sloping ridges covered with shorter grasses, which serve for the support of large herds of beef cattle. The wooded portions of the terrain are dotted with clumps and belts of trees of moderate size, giving them a park-like appearance. In winter it is generally very cold, but this is occasionally reduced by a warm wind from the west, known as the Chinook.

A Geological Survey of Canada map published in 1970 shows the following physiographic regions to be present at least partially within Alberta:^[1]

Mountains

Within about {{convert|100|km|spell=in|-1}} of the mountains there is constantly in view, in clear weather, a line of snowy peaks along the western horizon. This continues for hundreds of kilometres northwestward. The Canadian Rockies are ascended by a gradual approach from the east, but are exceedingly abrupt on their transalpine slope in British Columbia. The peaks of these mountains are majestic, many of them reaching a height of more than {{convert|3|km|spell=in|}} above the sea. Among the more notable of these are:

Historical travelling through these mountains was difficult, and alpine passes became very important. The most noted of the Alberta passes are:

The Caribou Mountains are not part of the Canadian Rockies, but are located in the northern Alberta, constituting an elevated plateau in the northern plains. They reach an altitude of {{cvt|1030|m||}}, almost {{cvt|700|m||}} higher than the surrounding area.

While not considered mountains, the Cypress Hills, located in southern Alberta, on the Saskatchewan border, constitutes the highest point between the Rocky Mountains and Labrador. They reach a maximum elevation of {{cvt|1468|m||}}, {{cvt|600|m||}} above the surrounding prairie.

Water

With the exception of the southern section, the province of Alberta may be said to be well watered. Rising from numerous valleys on the Alberta declivity of the Rocky Mountains between the international boundary line and 52° north are streams which unite to form the Oldman River, and farther north the Bow River. Running eastward these two rivers unite about 112° west, and flow on under the name of the South Saskatchewan River. North of 52° north many small streams unite to form the Red Deer River, which flowing southeastward joins the South Saskatchewan near 110° west. Between 52° and 53° north rises the great river, the North Saskatchewan. It receives a southern tributary, the Battle River, which joins it about 108° west. Pursuing their courses eastward the North and South Saskatchewan rivers unite in the Saskatchewan River (Cree, rapid-flowing river), which finds its way to Lake Winnipeg, and thence by way of Nelson River to Hudson Bay. It is one of the mightiest rivers of the continent.

At Mount Athabasca, there is an unusual occurrence where the water flows either to the Pacific Ocean on the western slope, the Arctic Ocean on the northeast, and the Atlantic Ocean on the southeast.

In the northern part of the province, between 53° and 54° north, all the waters of Alberta flow toward the Arctic Ocean. Starting at Mount Athabasca, the Athabasca River runs north and empties into Lake Athabasca near 58° north. North of 56° north flows through and from the Rocky Mountains as the Peace River. After descending northeastward to within a few miles of Lake Athabasca, it is met by a stream emerging from that lake. The united river carrying down the waters of the Athabasca slope is called the Slave River, which, passing through Great Slave Lake, emerges as the great Mackenzie River, which falls into the Arctic Ocean. Alberta thus gives rise to the two great rivers, the Saskatchewan and the Mackenzie.

While a number of fresh water, or in some cases brackish, lakes each less than 260 km² (100 mi²) in extent are situated in Alberta, two of more considerable size are found. These are Lake Athabasca, 7898 km² (3085 mi²) in extent, of which the greater part is in the province of Saskatchewan, and the other Lesser Slave Lake 1,160 km² (600 mi²) in area.

Climate

As Alberta extends for approximately {{convert|1200|km|mi|abbr=on}} from north to south, it is natural that the climate should vary considerably between parallels of 49° and 60° north and also between approximately 110° and 120° west. It is also further influenced by the different altitudes found in the province.

In general, Alberta's climate is dry, due to the rain shadow effect of the Rocky Mountains and Pacific Coast Ranges to the west, and continental, due to its distance from any large body of water.

Southern Alberta

Most of Southern Alberta east of the Rockies and outside of the Cypress Hills, especially Palliser's Triangle, is a dry steppe, with most locations having an annual average precipitation of 280-430mm. Under the Köppen climate classification, most places in Southern Alberta are either semi-arid (Köppen climate classification BSk), or humid continental (Köppen climate classification Dfb)^[2] (it should be noted that the "humid" designation denotes that these climates do not meet the criteria to be semi-arid, not that they necessarily have high humidity levels). Most places in Southern Alberta that fall under the "humid continental" classification are close to the borderline between semi-arid and humid continental. This region has the hottest summer temperatures in Alberta and quite cold winters though chinook winds ameliorate the cold winter temperatures temporarily when they pass over. The natural vegetation of this region is mainly dry mixedgrass prairie, grading to mixedgrass prairie, and then fescue prairie as precipitation increases with higher altitude and/or latitude.^[3] This area is prone to drought and farming here is not successful without significant irrigation.

Central Alberta

Central Alberta has a dry continental climate, with most places falling under the humid continental classification (Köppen climate classification Dfb), though some areas in the southeast of this region, close to the border with Saskatchewan around Oyen, are semi-arid (Köppen BSk).^[2] Precipitation levels here are generally higher than in Southern Alberta, though the driest areas of Alberta, around Empress, are in Central Alberta. This region generally has cooler temperatures than Southern Alberta in both summer and winter, due to the decreased amount of solar radiation received, and the lower frequency of chinooks blowing through the region. After Southern Ontario, Central Alberta is the region in Canada most likely to experience tornadoes. Most of Central Alberta is covered by aspen parkland, but the driest areas have mixedgrass and even dry mixedgrass prairie, while the wetter and/or cooler areas are covered in mixed boreal forest.^[3] The wetter parts of this region, around Edmonton, have some of the most fertile land in the Canadian Prairies.

Northern Alberta

Northern Alberta is the coldest region of Alberta, with most places having a subarctic climate (Köppen climate classification Dfc) though some areas in the south of this region, as well as much of the Peace River Country, have a humid continental climate (Köppen climate classification Dfb).^[2] Winters in Northern Alberta are long, very cold, and harsh, while summers are short and warm. Precipitation levels are generally lower than Central Alberta and similar to Southern Alberta, but lower evapotranspiration results in there being greater effective precipitation than Southern Alberta. Natural vegetation in Northern Alberta consists primarily of mixed and coniferous taiga, with aspen parkland in the Peace River Country.^[3] With the exception of the Peace River Country, this region is generally quite poor for agriculture.

Rocky Mountains and Cypress Hills

Lower elevations of the Rocky Mountains and all but the highest elevations of the Cypress Hills have a humid continental climate (Köppen climate classification Dfb).^[2] These areas have snowy but mild winters due to the warming effect of chinook winds, and cool summers due to their high elevation. As altitude increases and the subalpine zone is reached, this grades into a subarctic climate (Köppen climate classification Dfc),^[2] with much harsher winters and even cooler summers. Above the tree line, an alpine/polar climate (Köppen climate classification ET) prevails. Conditions this high are even colder and very windy. Precipitation is higher in these elevated regions than elsewhere in Alberta, and this supports forests of lodgepole pine and trembling aspen mixed with fescue grasslands in the montane areas, Engelmann spruce and subalpine fir forests in the subalpine zone, and heather, sedges and mountain avens in the alpine zone above the tree lines.

Ecology

Lists of ecological regions and zones

According to the provincial government's Natural Regions Committee, the following natural regions and subregions are found in Alberta:^[12]

According to the Commission on Environmental Cooperation and Environment Canada, the following ecozones are found in Alberta:

According to the World Wide Fund for Nature, the following ecoregions are found in Alberta:

See also

References

1. ^{{cite web|url=http://r.duckduckgo.com/l/?kh=-1&uddg=http%3A%2F%2Fgeogratis.gc.ca%2Fapi%2Fen%2Fnrcan-rncan%2Fess-sst%2F34acdc40-c813-5a09-aafe-a3470e1e56b5.html |title=l/ at DuckDuckGo |publisher=R.duckduckgo.com |date= |accessdate=2018-10-02}}
2. ^¹²³⁴{{cite web|url=http://people.eng.unimelb.edu.au/mpeel/Koppen/North_America.jpg|title=Köppen Climate Classification Map of North America|accessdate=2010-08-20}}
3. ^¹²{{cite web |url=http://www.albertaparks.ca/pubsandmedia/nsr2005_final_letter.pdf |title=Natural Regions and Subregions of Alberta Map |accessdate=2010-08-20 |deadurl=yes |archiveurl=https://web.archive.org/web/20100821074549/http://www.albertaparks.ca/pubsandmedia/nsr2005_final_letter.pdf |archivedate=21 August 2010 |df=dmy }}
4. ^{{cite web |title=Canadian Climate Normals 1981-2010 |url=http://climate.weather.gc.ca/climate_normals/results_1981_2010_e.html?stnID=2205&lang=e&dCode=1&province=ALTA&provBut=Go&month1=0&month2=12 |website=Environment Canada |publisher=Environment Canada |accessdate=August 22, 2018 |archiveurl=https://web.archive.org/web/20180822230253/http://climate.weather.gc.ca/climate_normals/results_1981_2010_e.html?stnID=2205&lang=e&dCode=1&province=ALTA&provBut=Go&month1=0&month2=12 |archivedate=August 22, 2018}}
5. ^{{cite web |title=Canadian Climate Normals 1981-2010 |url=http://climate.weather.gc.ca/climate_normals/results_1981_2010_e.html?stnID=2273&lang=e&dCode=1&province=ALTA&provBut=Go&month1=0&month2=12 |website=Environment Canada |publisher=Environment Canada |accessdate=August 22, 2018 |archiveurl=https://web.archive.org/web/20180822225818/http://climate.weather.gc.ca/climate_normals/results_1981_2010_e.html?stnID=2273&lang=e&dCode=1&province=ALTA&provBut=Go&month1=0&month2=12 |archivedate=August 22, 2018}}
6. ^{{cite web |title=Canadian Climate Normals 1981-2010 |url=http://climate.weather.gc.ca/climate_normals/results_1981_2010_e.html?stnID=1867&lang=e&dCode=1&province=ALTA&provBut=Go&month1=0&month2=12 |website=Environment Canada |publisher=Environment Canada |accessdate=August 22, 2018 |archiveurl=https://web.archive.org/web/20180822231037/http://climate.weather.gc.ca/climate_normals/results_1981_2010_e.html?stnID=1867&lang=e&dCode=1&province=ALT |archivedate=August 22, 2018}}
7. ^ . Retrieved 6 April 2010.
8. ^Canadian Climate Normals 1971–2000. Retrieved 7 July 2009.
9. ^Canadian Climate Normals 1971–2000, accessed 20 September 2009
10. ^Canadian Climate Normals 1971–2000 - Lake Louise, Alberta, accessed 19 February 2010
11. ^Canadian Climate Normals 1971–2000 - Cypress Hills, Saskatchewan, accessed 20 August 2010
12. ^Natural Regions Committee 2006. Natural Regions and Subregions of Alberta. Compiled byD.J. Downing and W.W. Pettapiece. Government of Alberta. Pub. No. T/852., http://www.cd.gov.ab.ca/preserving/parks/anhic/Natural_region_report.asp{{dead link|date=October 2017 |bot=InternetArchiveBot |fix-attempted=yes }}