vicky3 2009-10-8 12:12
南極
南極是地球上氣溫最低的地方.在這裡.熱能無法聚集.太陽的輻射能量有百分之八十被冰和雪反射掉.
內陸地區的平均溫度即使在最溫暖的季節也只有攝氏零下二十度至三十度.
[img]http://aycu36.webshots.com/image/34115/2005900003327713823_rs.jpg[/img]
距今一億八千萬年前.南極大陸和澳洲及南美大陸是連成一塊的.稱為岡瓦納大陸.是從盤古超大陸分裂出來的.
[img]http://aycu09.webshots.com/image/32568/2004430723440193061_rs.jpg[/img]
從發現的化石可以得知.當時的南極大陸氣候相當溫暖.如今卻成為地球上最寒冷的地方.對於地球的氣候有相當大的影響.
[img]http://aycu04.webshots.com/image/35603/2005924487147992840_rs.jpg[/img]
在這塊酷寒的大陸現在由於某些原因而倍受矚目.那就是其上空平流層的臭氧大量減少.形成所謂的臭氧洞.原本以為只是局部的現象.但現在卻以被視為和全球性臭氧層的破壞有關.
或許.地球盡頭的南極大陸.對地球的危機是最敏感的.
[img]http://aycu38.webshots.com/image/34957/2004450931476914822_rs.jpg[/img]
位於南極點四周.上面覆蓋著冰雪的大陸.為世界第五大陸.四周圍繞著多風暴且易結冰的南極海.
[img]http://aycu15.webshots.com/image/33054/2005955243356103169_rs.jpg[/img]
南極洲幾呈圓形.這塊大陸幾乎完全位於南極圈內.面積約有1320萬 9千平方公里.
南極洲平均高度為1830公尺.幾乎為其他大陸平均高度的兩倍.
加上陸地上所覆蓋的冰雪.厚度高達2440公尺.使得南極洲的總平均高度抬高為4270公尺.
海岸線長 30010公里的南極洲海域.並佈滿冰山.冰河的冰塊和大浮冰.
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