注册 登录  
 加关注
   显示下一条  |  关闭
温馨提示!由于新浪微博认证机制调整,您的新浪微博帐号绑定已过期,请重新绑定!立即重新绑定新浪微博》  |  关闭

似水流年

人生有度方坦然。。。

 
 
 

日志

 
 
关于我

总有一种声音,让人想起从前,总有一份记忆,徘徊在心的边缘,总有一种守侯,即使脚步渐行渐远。 流水涓涓,仿佛从不曾离去,在我们生命的故事中,细数着流年……

网易考拉推荐

Glacier Formation  

2013-02-19 17:10:29|  分类: 【英语资料】 |  标签: |举报 |字号 订阅

  下载LOFTER 我的照片书  |

Glacier Formation

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.

 

Paragraph1: 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.

1. The word “interlocked” in the passage is closest in meaning to 2

intermediate

linked

frozen

fully developed

 

2. According to paragraph 1, which of the following does NOT describe a stage in the development of firn? (1)

Hexagonal crystals become larger and interlock to form a thick layer.

Snow crystals become compacted into grains.

Granules recrystallize after melting, refreezing, and further compaction.

Grains become denser owing to reduced air space around them.

 

Paragraph2: 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.

 

3. The word “match” in the passage is closest in meaning to (4)

measure

enlarge

approximate

equal

 

4. The word “transform” in the passage is closest in meaning to (3)

break

push

change

extend

 

5. According to paragraph 2, surplus snow affects a glacier in all the following ways EXCEPT: (4)

It provides the pressure needed to cause glacial ice to flow.

It offsets losses of ice due to melting, evaporation, and calving.

It brings about the formation of firn in the snow it buries.

It results in temperate glaciers that are thicker than polar glaciers.

 

6. Paragraph 2 implies that which of the following conditions produces the fastest moving glaciers?2

A climate characteristic of the polar regions

A thick layer of ice in a temperate climate

Long, warm summers

Snow, firn, and ice that have been buried for several years

 

Paragraph3: 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.

 

7. The word “deceiving” in the passage is closest in meaning to 4

approximate

exaggerated

unusual

misleading

 

8. Why does the author consider the hypothetical melting of the world's glaciers?2

To contrast the effects of this event with the opposite effects of a new ice age

To emphasize how much water is frozen in glaciers

To illustrate the disastrous effects of a warming trend

To support the claim that glaciers are part of Earth's hydrologic cycle

 

9. The discussion in paragraph 3 answers all the following questions EXCEPT:3

Where is most of Earth's freshwater?

What effect would a new ice age have on sea levels?

What is the total amount of water in Earth's oceans?

  

Paragraph4: 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.

 

10. The word “static” in the passage is closest in meaning to 1

unchanging

usable

thick

harmless

 

11. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.2

As a glacier moves, it leaves behind rock formations that have been engulfed, pushed, and dragged by the glacier.

Glaciers reshape the landscape by carving into rock and transporting the resulting debris to distant locations.

Glaciers carve the hardest rock formations with great energy and slowly reshape them into debris.

The tremendous energy of slowly moving glaciers transports and finally deposits rock debris into large rock formations.

 

Parargraph5: 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.

 

12. According to paragraph 5, in what way is the present time unusual in the history of Earth?1

There are glaciers.

More land is covered by glaciers than at anytime in the past.

There is no ice age.

No glaciers are found in Australia.

 

Paragraph1: 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.

 

13. Look at the four squares [] that indicate where the following sentence could be added to the passage.

Firn has the appearance of wet sugar, but it is almost as hard as ice.

Where would the sentence best fit?3

 

 

 

 

 

14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

 

Glaciers are part of Earth's hydrologic cycle.

Glaciers, which at present…

When there are glaciers…

When glacial ice reaches…

Answer Choices

Glaciers, which at present contain 80 percent of Earth's freshwater, form when accumulated snow is compressed and recrystallized into ice over a period of years.

When there are glaciers on Earth, water is cycled through the glacier system, but the cycle period may be hundreds of thousands of years during periods of ice ages.

The glacial system is governed by precipitation and temperature in such a way that glaciers cannot form in temperate latitudes.

When glacial ice reaches a depth of 30 meters, the weight of the ice causes ice crystals at the bottom to flow, and the resulting movement of the glacier carves the landscape.

If global warming melted the world's glaciers, sea level would rise about 60 meters worldwide.

Glaciers have had little effect on Earth's surface because only 2 percent of Earth's water is currently contained in glaciers, and there are fewer glaciers now than at most times in the past.


 

  

参考答案:

1. 2

2. 1

3. 4

4. 3

5. 4

6. 2

7. 4

8.2

9. 3

10. 1

11. 2

12. 1

13. 3

14. Glaciers, which at present…

When there are glaciers…

When glacial ice reaches…


参考译文:冰川的形成

 

冰川是一种缓慢移动的巨大的冰块,这种冰块是由于每年降雪多于融化而积累起来的。那些如六角晶体的降雪一旦飘落在地表,雪花就迅速压缩成大量的小而圆的颗粒。由于压缩与融化,这些颗粒周围空气空间也随之减少。随着进一步的融化,再结冰,以及承受位于上方的新的降雪的重量,这些积雪达到了一种介于冰片与冰块的中间阶段,该阶段可使颗粒物再次形成晶状体,这个阶段被称作积雪过程。随着不断增加的时间、压力和那些位于上方的融雪重新结冰后,那些较小的积雪颗粒开始变大并与透明的蓝色的冰层相连接。当这些冰块足够厚的时候,往往是超过30米,积雪的重量就会使这些冰晶朝着底部变得具有可塑性,并且会从有积雪的地方流入或者流出。

 

冰川是全球水循环的一部分并且冰川是一个开放的系统,降雪作为这个系统的输入物,融化作为主要的输出物。冰川系统主要由两个基本的气候变量所控制:降雨和温度。为了保持或者增加一个冰川的体积,它就必须拥有足够的降雪量,这些降雪量需要能够抵消或者超过每一年因为融雪、蒸发或者以海洋和湖泊中的冰山形式的裂冰的数量。如果夏季温度过高,所有的上一季的降雪就都会融化。对于冰川的形成,剩余的降雪就非常重要。有剩余的积雪就能够积累,并且由于多年的积雪形成的压力使得雪被埋在一个相当深的冰川里,这个深度可以使冰块流动。冰川有时会被按照温度分为快速流动冰川和慢速流动极地冰川。

 

冰川是仅次于海洋的第二大水源。地球上有大约百分之二的水源目前处于冰冻状态。但是,百分之二有可能是一个欺骗性的数据,因为全球有超过百分之八十的淡水以冰块的形态存在于冰川中,其中绝大多数的在南极洲。如果我们估算理论上全球冰川融化后所释放的水量,那么冰块的总量会是一个让人叹为观止的数量。海平面将会上升差不多60米。这会显著的改变星球的地理属性。相反的,如果另一个冰川时代来临,海平面会急速的下降。在最近的一个冰河时代,海平面下降了差不多120米。

 

当在高山或者极地地区降雪时,这些降雪会形成冰川系统的一部分。不像是降雨,非常快的返回至海洋或者大气中,降雪要成为冰川的一部分需要一个非常缓慢的循环系统。在这里,水会以冰的形态存在几百上千年,直到作为融水释放进入流水系统。但是,同时冰并不是静止的。冰川在巨大的能量伴随下在陆地上缓慢的移动,甚至切碎最坚硬的岩石,从而在吞没、推动、拉拽直到最后在离原址遥远的地方沉淀下这些岩石的残余物,在这个过程中它重新塑造了地形地貌。所以,冰川创造出了非常多的地形,这些地形保持不变直到有冰层覆盖在其表面。

 

纵观地球的大部分历史,冰川并没有存在,直到最近才有百分之十的冰川覆盖在地表。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可以找到冰川。在不久的过去,24万年至1万年前,有差不多三分之一的地表被上千米厚的冰层定期的覆盖。在更遥远的过去,其他冰川时代也存在过。

  评论这张
 
阅读(759)| 评论(0)
推荐 转载

历史上的今天

在LOFTER的更多文章

评论

<#--最新日志,群博日志--> <#--推荐日志--> <#--引用记录--> <#--博主推荐--> <#--随机阅读--> <#--首页推荐--> <#--历史上的今天--> <#--被推荐日志--> <#--上一篇,下一篇--> <#-- 热度 --> <#-- 网易新闻广告 --> <#--右边模块结构--> <#--评论模块结构--> <#--引用模块结构--> <#--博主发起的投票-->
 
 
 
 
 
 
 
 
 
 
 
 
 
 

页脚

网易公司版权所有 ©1997-2017