托福 托福 15 - Glacier Formation
题目
1 2 3 4 5 6 7 8 9 10 11 12 13 14
7.The word “deceiving” in the passage is closest in meaning to
  • A.approximate
  • B.exaggerated
  • C.unusual
  • D.misleading
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    答案解析:
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    Glaciers are slowly moving masses of ice that have accumulated on land in areas where more snowfalls during a year than melts. Snow falls as hexagonal crystals, but once on the ground, snow is soon transformed into a compacted mass of smaller, rounded grains. As the air space around them is lessened by compaction and melting, the grains become denser. With further melting, refreezing, and increased weight from newer snowfall above, the snow reaches a granular recrystallized stage intermediate between flakes and ice known as firn. With additional time, pressure, and refrozen meltwater from above, the small firn granules become larger, interlocked crystals of blue glacial ice. When the ice is thick enough, usually over 30 meters, the weight of the snow and firn will cause the ice crystals toward the bottom to become plastic and to flow outward or downward from the area of snow accumulation.

    Glaciers are open systems, with snow as the system’s input and meltwater as the system's main output. The glacial system is governed by two basic climatic variables: precipitation and temperature. For a glacier to grow or maintain its mass, there must be sufficient snowfall to match or exceed the annual loss through melting, evaporation, and calving, which occurs when the glacier loses solid chunks as icebergs to the sea or to large lakes. If summer temperatures are high for too long, then all the snowfall from the previous winter will melt. Surplus snowfall is essential for a glacier to develop. A surplus allows snow to accumulate and for the pressure of snow accumulated over the years to transform buried snow into glacial ice with a depth great enough for the ice to flow. Glaciers are sometimes classified by temperature as faster-flowing temperate glaciers or as slower-flowing polar glaciers.

    Glaciers are part of Earth’s hydrologic cycle and are second only to the oceans in the total amount of water contained. About 2 percent of Earth’s water is currently frozen as ice. Two percent may be a deceiving figure, however, since over 80 percent of the world’s freshwater is locked up as ice in glaciers, with the majority of it in Antarctica. The total amount of ice is even more awesome if we estimate the water released upon the hypothetical melting of the world’s glaciers. Sea level would rise about 60 meters. This would change the geography of the planet considerably. In contrast, should another ice age occur, sea level would drop drastically. During the last ice age, sea level dropped about 120 meters.

    When snowfalls on high mountains or in polar regions, it may become part of the glacial system. Unlike rain, which returns rapidly to the sea or atmosphere, the snow that becomes part of a glacier is involved in a much more slowly cycling system. Here water may be stored in ice form for hundreds or even hundreds of thousands of years before being released again into the liquid water system as meltwater. In the meantime, however, this ice is not static. Glaciers move slowly across the land with tremendous energy, carving into even the hardest rock formations and thereby reshaping the landscape as they engulf, push, drag, and finally deposit rock debris in places far from its original location. As a result, glaciers create a great variety of landforms that remain long after the surface is released from its icy covering.

    Throughout most of Earth’s history, glaciers did not exist, but at the present time about 10 percent of Earth’s land surface is covered by glaciers. Present-day glaciers are found in Antarctica, in Greenland, and at high elevations on all the continents except Australia. In the recent past, from about 2.4 million to about 10,000 years ago, nearly a third of Earth’s land area was periodically covered by ice thousands of meters thick. In the much more distant past, other ice ages have occurred.

    冰川就是缓慢移动的巨大冰块,这种冰块是由于每年降雪量大于融雪量不断积累形成于陆地的。雪花降落时是六角晶体,可一旦落在地面,雪花就迅速凝结成大量小而圆的颗粒。由于凝结和融化这些颗粒周围空气空间也随之减少,从而颗粒就会变得更为紧密。雪继续融化、再结冰,并且还要承受上方新的积雪增加的重量,待这些积雪达到一种介于冰片与冰之间的阶段,颗粒物便会再次形成晶状体,这一阶段被称作积雪过程。时间、压力不断增加,并且位于上方的融雪重新结冰,那些较小的积雪颗粒开始变大且与透明的蓝色冰层连结。当这些冰块足够厚(一般是30米以上),积雪的重量就会使底部的冰晶变得具有可塑性,会从有积雪的地方流入或者流出。 冰川是开放的系统,降雪是该系统的补给水源,融雪是该系统的主要输出水源。冰川系统受两个基本气候变量控制:降水和气温。要保持或增加冰川的体积,就必须具备足够的降雪量,以抵消或者超过每年因融雪、蒸发或者以海洋和湖泊中的冰山形式的裂冰的数量。如果夏季温度持续长时间的高温度,上一个冬季所有的降雪都会融化。剩余降雪对形成冰川非常重要。有剩余的积雪就能够积累,并且由于多年积雪形成的压力,将积雪转化为流动冰,深度足以保证冰川流动。按照温度分类,冰川可分为快速流动温带冰川和慢速流动极地冰川。 冰川是地球水循环的一部分,水容量仅次于排名第一的海洋。目前地球上大约有2%的水源处于冰冻状态。2%这个数字可能并不属实,因为全球有超过80%的淡水以冰块的形态存在于冰川中,其中大部分处于南极洲。如果我们估算出全球冰川融化后所释放的水量,储水量必定让人叹为观止。海平面将会上升60米左右。这会显著的改变地球的地理属性。相反,如果另一个冰期到来,海平面会迅速降低。在上一个冰期,海平面下降了120米左右。 当雪降落在高山或者极地地区,便成为冰川系统的一部分。这和降水不同,降水可以迅速回到海洋或者大气中,但降雪要成为冰川的一部分,循环过程非常缓慢。在这里,水会以冰的形态存在几百或上千年,直到作为融水释放进入流水系统。然而,冰也并非完全静止。在巨大的能量的作用下 ,冰川在陆地上缓慢移动,甚至切碎最坚硬的岩石,将其吞没、推动、拉拽,最后在离原位置很远的地方沉淀下这些岩石的残余物,在这个过程中它重新改造了地形地貌。因此,冰川创造出了各种各样的地形,冰层脱离表面之后,这些地形能够长时间保持不变。 纵观地球历史,大部分时期内并不存在冰川,但现在10%的地表为冰川覆盖。目前,在南极洲、格陵兰岛,以及除了澳洲以外大陆的高海拔地区都有冰川存在。不久以前,在24万年至1万年前,大约三分之一的地表被上千米厚的冰层定期覆盖。在更遥远的过去,其他冰期也曾出现过冰川覆盖地表的情况。

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    最新提问
    • wx_6697
      觉得B C 意思一样,不知道选哪个
    • wx_5576
      这道题C为什么对,E为什么不对?
    • wx_5576
      B为什么不能选啊?
    • wx_6697
      TPO30 passage 2 Q5我选的 D,不明白为啥不对?
    • wx_6697
      鑫哥,TPO6passage3Q5 答案是给错了吗?好多人都选A
    • wx_6697
      这题也很容易选错选成了D
    • wx_6697
      这道题A为什么错了
    • 芊儿
      为什么这道题不选c??a中的variety不是应该对应文中的differentiating 吗??求解!
    • wx_1000
      这道题不选E是因为太细节了吗
    • 王金阁
      这个题为什么不选C啊。。。
    • 芊儿
      这道题的D选项不是和文中的better able to reproduce in open settings相对应么??
    • 风荨火
      有大佬解释一下这个为啥选D嘛?
    • 以沫
      请问这个D 在哪里提现?为什么D错?
    • 芊儿
      第六题 的C选择为什么不对,感觉A是明显驳斥啊...
    • wx_6697
      鑫哥,这道题D是从哪里看出来的
    • wx_6697
      这题选的A,根据是Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.想问鑫哥为啥不选A
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      这题我选的是C依据是into a new habitat outside of its natural range, it may adapt to the new environment and leave its enemies behind.C为啥错了呢?鑫哥
    • wx_8861
      F选项的weather-related destruction在哪里体现了呢?原文最后一段的开头Among the costs里的costs是不是打错了?应该是coast?
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      与托福的斗争史 去解答 去解答
      这题为什么选C?
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B哪里错了
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B为啥不对
    • 李浩然
      B选项错误,是因为残缺么?
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    • wx_7695
      鑫哥,从哪里看出来这个masks 不是use呀,原文说了wear呀
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      @鑫哥,这题the damage will continue 不应该对应前面的 the target species evolves resistance to it,然后As one pesticide replaces another,不应该是结束了time cycle 吗
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      鑫哥,想知道E错在哪里?
    • wx_7695
      鑫哥,B选项 cannot extended to earlier geological periods. 原文说的意思是后来的进化无法估计吧
    • wx_2163
      B为什么不选
    • wx_7780
      鑫哥,这个哪里看不use了。BD是修饰错,C是无中生有,怎么能直接选出A?
    • 100
      看到第一句话,以为是中心句就选了A... 为什么不能选A呢
    • 100
      为什么选b?
    • gu33
      请问下 这里选D的原因是 因为 evolutionary approach 对应着 原文的 Rates of evolution 嘛? 这里我选了C。。不是很懂 插入句和 D的关系 求解答
    • 我是啦啦啦
      我是啦啦啦 去解答 去解答
      这个题A哪里错了?是因为主语不对吗?这个C比A多一步推理啊
    • haiyuqiao
      鑫哥,D选项里的19世纪出现了很多假设,原文中并没有提到啊
    • wx_7060
      为什么选a 呢。我觉得a是细节。F哪错了?
    • wx_1105
      我想问一下,这道题为什么不能选A呢?
    • wx_8122
      D为什么不选
    • wx_1655
      f选项哪里说了
    • chaulaw
      鑫哥,原文是below经济损害水平,D是一触发经济损害就用,这也对吗?
    • chaulaw
      interclan婚姻是对的吗?不是只在自己的family结婚扩大家族吗?
    • wx_6697
      鑫哥,这道题答案是不是错了,好多人选D 我也选的D求解答
    • wx_6697
      这道题应该是一道易错题,每个选项的都有,然而我选的A错了,求解
    • wx_6697
      鑫哥,这题的C是怎么得到的?B也没有找到啊?难道不是应该选B
    • wx_6697
      鑫哥,还有这个,好多人选A答案是不是错了
    • wx_6697
      求问D是从哪里得出来的,我选的B呀哎呀
    • wx_4185
      it is difficult to say how far they were intended to be portraits rather than generalized images 这句话怎么理解呢
    • 此楠楠
      请问下这个插入题怎么选的呢?
    • 此楠楠
      求鑫哥讲解下A选项。。。 Even though in error, Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.