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.
Paragrapht 2 (the above) implies that which of the following condition produces the fastest moving glaciers?
1. the climate characteristic of the polar region
2. a thick layer of ice in the temperate climate
3. long warm summer
4. snow, firn and ice that have been buried for many years.
答案是2.怎么看出来的呢,难道是“ Glaciers are sometimes classified by temperature as faster-flowing temperate glaciers or as slower-flowing polar glaciers. ”
关键是这句前面两句要读懂 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.
说的是,如果温度高而且持续时间长,snowfall将melt,这surplus snawfall很关键. a surplus 使得snow囤积并且使得snow的pressure增加,使得buried snow 转变为glacial ice 伴随很一个可以使得ice flow的强大程度。
(翻译的我都晕掉了。但是大致意思就这样。出题点在这几句话里。此题较难。)