美國(guó)介紹
美國(guó)位于北美洲南部,東臨大西洋,西瀕太平洋,北接加拿大,南靠墨西哥及墨西哥灣.
全境由東向西可分為5個(gè)地理區(qū)：東南部沿岸平原分：大西洋沿岸平原和墨西哥沿岸平原兩部分.
這一地帶海拔在200米以下,多數(shù)由河川沖積而成,特別是密西西比河三角洲,是世界上最大的三角洲,土質(zhì)油黑,土壤肥沃.河口附近有一些沼澤地.位于這一地理區(qū)的佛羅里達(dá)半島是美國(guó)最大的半島阿巴拉契亞山脈位于大西洋沿岸平原的西側(cè),基本與海岸平行,長(zhǎng)約2300多公里,一般海拔1000－1500米,由幾條平行山脈組成.內(nèi)地平原呈倒三角形,北起漫長(zhǎng)的美國(guó)與加拿大的邊界,南達(dá)大西洋沿岸平原的格蘭德河一帶.西部山系由西部?jī)蓷l山脈所組成,東部為落基山脈,西部為內(nèi)華達(dá)山脈和喀斯喀特山脈.舊褶曲運(yùn)動(dòng)后的產(chǎn)物.內(nèi)華達(dá)山脈的惠特尼峰海拔4418米,為美國(guó)大陸最高點(diǎn),喀斯喀特山脈的雷尼爾山海拔4392米,僅次于惠特尼峰.西部山間高原由科羅拉多高原、懷俄明高原、哥倫比亞高原與大峽谷組成,為美國(guó)西部地質(zhì)構(gòu)造最復(fù)雜的地區(qū).大峽谷位于亞利桑那州西北部,由一系列迂回曲折、錯(cuò)綜復(fù)雜的山峽和深谷組成,氣勢(shì)雄偉,巖壁陡峭,為世界上罕見的自然景觀.美國(guó)河流湖泊眾多,水系復(fù)雜,從總體上可分為三大水系：凡位于落基山以東的注入大西洋的河流都稱為大西洋水系,主要有密西西比河、康涅狄格河和赫得森河.其中密西西比河全長(zhǎng)為6020公里,居世界第三位.凡注入太平洋的河流稱太平洋水系.主要有科羅拉多河、哥倫比亞河、育空河等.北美洲中東部的大湖群.包括蘇必利爾湖、密歇根湖、休倫湖、伊利湖和安大略湖,總面積24.5萬平方公里,為世界最大的淡水水域,素有“北美地中?！敝Q,其中密歇根湖屬美國(guó),其余4湖為美國(guó)和加拿大共有.蘇必利爾湖為世界最大的淡水湖,面積在世界湖泊中僅次于里海而居世界第二位.
美國(guó)的氣候大部分地區(qū)屬溫帶和亞熱帶氣候,僅佛羅里達(dá)半島南端屬熱帶.阿拉斯加州位于北緯60至70度之間,屬北極圈內(nèi)的寒冷氣候區(qū)；夏威夷州位于北回歸線以南,屬熱帶氣候區(qū).但由于美國(guó)幅員遼闊,地形復(fù)雜,各地氣候差異較大.大體可分為5個(gè)氣候區(qū)：東北部沿海的溫帶氣候區(qū).這一區(qū)域因受拉布拉多寒流和北方冷空氣的影響,冬季寒冷,1月份平均溫度為-6℃左右,夏季溫和多雨,7月份平均溫度為16℃左右.年平均降水量為1000毫米左右.東南部亞熱帶氣候區(qū).因受墨西哥灣暖流的影響,氣候溫暖濕潤(rùn),1月份平均溫度為96℃,7月份平均溫度為24～27℃,年平均降水量為1500毫米.中央平原的大陸性氣候區(qū).這一區(qū)域呈大陸性氣候特征,冬季寒冷,1月份平均溫度為-14℃左右,夏季炎熱,7月份平均氣溫高達(dá)27～32℃.年平均降水量為1000～1500毫米.西部高原干燥氣候區(qū).這一區(qū)域內(nèi)陸性氣候,高原上年溫差較大,科羅拉多高原的年溫差高達(dá)25℃.年平均降水量在500毫米以下,高原荒漠地帶降水量不到250毫米.太平洋沿岸的海洋性氣候區(qū).這一區(qū)域冬暖夏涼,雨量充沛.1月份平均氣溫在4℃以上,7月份平均氣溫在20～22℃左右.年平均降水量為1500毫米左右.
美國(guó)的農(nóng)業(yè)、礦產(chǎn)和森林資源豐富,在世界上占有舉足輕重的作用. 美國(guó)的地理位置,氣候條件及地形結(jié)構(gòu)都是得天獨(dú)厚的.美國(guó)農(nóng)業(yè)用地(耕地和牧地)約為4.3億公頃,占地球全部農(nóng)業(yè)用地的10%左右.雨量充沛,土壤肥沃,糧食產(chǎn)量占世界總產(chǎn)量的1/5,主要農(nóng)畜產(chǎn)品如小麥、玉米、大豆、棉花、肉類等產(chǎn)量均居世界第一位.
美國(guó)礦產(chǎn)資源豐富,鐵礦石、煤炭、天然氣、鉛、鋅、銀、鈾、鉬、鋯等產(chǎn)量均居世界前列,但戰(zhàn)略資源如鈦、錳、錫、鈷、鉻、鎳等則主要依賴進(jìn)口.煤炭的總儲(chǔ)量為35996億噸,石油總儲(chǔ)量為240多億噸,天然氣儲(chǔ)量為56034億立方米.
美國(guó)擁有18億公頃的森林,占全國(guó)土地總面積的31.5%左右,主要樹種有美洲松、黃松、白松和橡樹類.
The United States introduced
In North America, southern United States, are Atlantic, the West Pacific Ocean, north to Canada, south through Mexico and the Gulf of Mexico.
From east to west throughout the territory can be divided into five geographical regions: the coastal plain in southeastern: Mexico and the Atlantic coastal plain Plain two parts.
This zone elevation of 200 meters below, the majority formed by the alluvial rivers, especially the Mississippi River delta, is the world's largest delta, soil and oil, fertile soil. Estuary near some marshland. Located in the geographical area of the Florida Peninsula is the largest peninsula in the Appalachian Mountains west side of the Atlantic coastal plain, basic parallel with the coast, more than 2,300 km long, the general 1000-1500 meters altitude, mountains formed by several parallel. The Plain was inverted triangle, a long North American and Canadian borders, the Southern Atlantic coastal plains along the Rio Grande River. Western mountains from the west is composed of two mountains, east of Rocky Mountains, the western Nevada mountains and karst mountain ash. Old fold after exercise products. Whitney Nevada mountain peak elevation of 4,418 meters, the highest point for the continental United States, the karst mountain ash Rainier Hill elevation 4,392 meters, after Whitney peak. Western mountain plateau by the Colorado Plateau, Wyoming plateau, Colombia and the Grand Canyon of the plateau, the western United States for the most complex geological structure areas. Grand Canyon in northwestern Arizona, a series of convoluted twists and turns, complicated and deep valley gorge formed momentum majestic, steep rock wall, the world's rare natural landscape. Many American rivers and lakes, River complex, in general, can be divided into three main river systems: Where in Rocky Mount and into the Atlantic east of the river are called Atlantic River, a major Mississippi River, Connecticut River and He was Morikawa. The length of the Mississippi River 6,020 kilometers, ranking third in the world. Where the rivers into the Pacific said Pacific River. Major Colorado River, Columbia River, the Yukon River. In the North-eastern Great Lakes. Including Lake Superior, Lake Michigan, Lake Huron, Lake Erie and Lake Ontario, a total area of 245,000 square kilometers, the world's largest freshwater waters, known as the "North American Mediterranean," said one Lake Michigan is the United States, the other four lakes were for the United States and Canada. Lake Superior, the world's largest fresh water lake, the lake area in the world, second only to being the second in the world and the Caspian Sea.
The United States is the most temperate climate and subtropical climate, only the southern peninsula of Florida is tropical. Alaska in the north between 60 to 70 degrees, is the cold Arctic climate zone; Hawaii in the south of the Tropic of Cancer, is a tropical climate zone. But because the United States, the sprawling complex terrain, climate around the larger differences. Generally can be divided into five climatic zones: Northeast coastal temperate climate zones. Labrador in the region due to the cold weather and the Northern cold, cold winter, the average temperature for January 6 ℃, mild wet summer, the average temperature in July is 16 ℃. The annual average rainfall of 1,000 mm around. Southeast subtropical climate zones. Because of the Gulf Stream, warm and humid climate, the average temperature in January is 96 ° C, an average July temperature of 24 to 27 ° C with an average annual rainfall of 1,500 mm. Central Plains continental climate zones. The region was of continental climate, the cold winter, the average temperature in January is about -14 ° C, hot summer, the average temperature in July was 27 to 32 ℃. The annual average rainfall of 1,000 mm to 1,500. Western Plateau dry climate zones. Inland climate in the region, greater temperature plateau last year, the Colorado Plateau, the temperature as high as 25 ℃. The average rainfall of 500 mm in the following, desert plateau less than 250 mm of precipitation. The oceanic climate in the Pacific Rim. Winter in the region, abundant rainfall. The average temperature in January in 4 ° C above the average temperature in July 20 to 22 ℃. The annual average rainfall of 1,500 mm around.
America's agricultural, mineral and forest resources in the world occupy the pivotal role. The United States location, weather conditions and terrain are unique structure. U.S. agricultural land (cropland and pasture), about 430 million hectares of agricultural land all of the Earth about 10%. Abundant rainfall, fertile soil of the world's total grain output of 1 / 5, the main agricultural and livestock such as wheat, corn, soybean, cotton, meat production tops in the world.
The United States rich mineral resources, iron ore, coal, natural gas, lead, zinc, silver, uranium, molybdenum, zirconium, tops in the world in terms of output, but strategic resources such as titanium, manganese, tin, cobalt, chromium, nickel, mainly rely on imports. The total coal reserves of 3.5996 trillion tons, the total oil reserves of over 240 million tons, and natural gas reserves of 5.6034 trillion cubic meters.
The United States has 1.8 billion hectares of forest, of the nation's total land area of about 31.5%, with the main species of American Song, Pinus ponderosa, White Pine and Oak category.