夜雨聆风Section II Reading Comprehension
Part A
Directions: Read the following four texts. Answer the questions below each text by choosing A, B, C or D. Mark your answers on the ANSWER SHEET.
Text 1
In 2019 the world's scheduled airlines flew roughly 61 billion kilometres, and on more than 40% of that distance the aircraft trailed a contrail behind them, as water vapour in their exhaust froze into ice crystals. Most such trails vanish within minutes. But over a smaller share of the distance flown, moisture already present in the surrounding air joins in the freezing, and a thin white line broadens into a persistent streak of cirrus-like cloud. At any given moment, such man-made clouds cover only about a thousandth of the sky. Yet their effect on the climate is far from negligible.
The reason lies in a subtle imbalance. Contrail ice crystals reflect incoming sunlight, which cools the planet by day. But they also trap outgoing infrared radiation and send some of it back towards the surface, much as greenhouse gases do—and this warming operates around the clock. On balance the warming wins out: by some estimates, the contrails left by a flight now warm the atmosphere more than the carbon dioxide emitted by that same flight's engines.
Crucially, this warming is not inevitable. Persistent contrails form only where the surrounding air is cold enough and already holds moisture that has not yet frozen; without particles to seed the process, that moisture would simply stay as vapour, and a contrail supplies exactly such particles by the trillion. These ice-supersaturated regions are typically only a few hundred metres thick, though they may stretch for hundreds of kilometres horizontally. Steer aircraft around them, in principle, and much of the associated warming disappears.
That principle is now being put to the test. A British-led consortium unveiled Operation Blue Skies on August 18th—by far the largest trial of contrail avoidance conducted so far—covering Shanwick, a swath of North Atlantic airspace lying west of the British Isles. Shanwick is an apt choice of testing ground: the air at cruising altitude there is reliably cold and damp, the corridor is heavily used by transatlantic traffic, and it is watched around the clock by European and American weather satellites. Despite accounting for only 0.4% of the planet's surface area, this single corridor is thought, according to model estimates, to generate around one-twentieth of the warming caused by contrails everywhere.
Over 20 to 40 days across two coming winters, controllers will nudge selected flights a few hundred metres below their planned altitude whenever conditions suggest a risk of persistent contrails, provided nothing else—turbulence, for instance—rules it out. Comparing satellite images from days with such adjustments and days without them should reveal, reliably, whether the intervention actually thins the cirrus cover it targets.
The costs look modest by comparison. Flying slightly lower burns a little more fuel, but earlier, smaller trials found the difference barely measurable, and one climate scientist reckons that on the worst-offending routes, an extra tonne of carbon dioxide from burning that fuel might avert as much as a hundred tonnes of CO2-equivalent contrail warming. Sceptics counter that chasing contrails could distract airlines from the harder, slower task of cutting the carbon dioxide they emit directly. That is a fair worry, but hardly a reason for inaction: unlike most climate fixes, keeping planes out of a few slivers of cold, damp sky is quick and cheap, and, should the trial succeed, it could be scaled up almost immediately.
21. It can be learned from Paragraphs 1 and 2 that persistent contrails ____
A. cover a large portion of the sky
B. cause more warming than cooling overall
C. form in much the same way as rain clouds
D. have grown less frequent since 2019
22. According to Paragraph 3, the persistence of a contrail chiefly depends on ____
A. how much fuel the aircraft has burned
B. the altitude at which the plane cruises
C. the size of the aircraft producing it
D. surrounding air conditions and available ice-forming particles
23. The figures given in Paragraph 4 are meant to show that ____
A. Shanwick's contribution to contrail warming is disproportionately large
B. the trial's location was chosen at random
C. satellite monitoring is especially accurate over the North Atlantic
D. transatlantic flights generally produce more contrails than other routes
24. The comparison mentioned in Paragraph 5 is designed to ____
A. identify which airlines comply best with new routes
B. calculate the total fuel savings achieved by the trial
C. determine whether the intervention reduces persistent contrails
D. warn pilots about turbulence along the flight path
25. Which of the following statements would the author agree with?
A. Contrail avoidance should take priority over cutting direct CO2 emissions
B. Contrail avoidance is a rare climate fix that is both fast and cheap
C. The worry that avoidance distracts from other climate efforts is groundless
D. Wide adoption of contrail avoidance depends on new aircraft design
附注：根据历年考研英语真题阅读题源外刊等，摘选最新文章，模拟仿真出题。
参考答案见以下。
Quick look: BDACB
21. B
依据第二段"On balance the warming wins out…now warm the atmosphere more than the carbon dioxide emitted by that same flight's engines"——净效应是增温而非降温。
22. D
依据第三段"form only where the surrounding air is cold enough and already holds moisture…a contrail supplies exactly such particles"——温湿条件+凝结核共同决定持续性。
23. A
依据第四段"accounting for only 0.4%…generate around one-twentieth of the warming"——面积占比与增温占比悬殊对比，凸显Shanwick"以小博大"。
24. C
依据第五段"should reveal, reliably, whether the intervention actually thins the cirrus cover it targets"——对比卫星图像的直接目的是检验干预是否奏效。
25. B
依据末段"unlike most climate fixes, keeping planes out of a few slivers of cold, damp sky is quick and cheap…could be scaled up almost immediately"——全文收束于"低成本、可快速推广"的定性判断。
【词汇注释】
supersaturated: adjective (STATE) containing more of a substance than can normally remain stable in solution or suspension, so that the excess separates out at the slightest disturbance 过饱和的（文中以复合词ice-supersaturated出现，指大气中水汽含量超过可稳定维持气态的程度，极易凝结成冰晶）
consortium: noun (GROUP) a group of companies, organisations or institutions that agree to work together on a shared project 联合体；财团（文中指联合发起"蓝天行动"的多家机构）
swath: noun (AREA) a long strip or wide area of something, especially of land or sky 一大片；一长条区域（文中指北大西洋上空一片划定的空域）
apt: adjective (SUITABLE) exactly right for a particular situation; fitting 恰当的；贴切的
nudge: verb (MOVE SLIGHTLY) to push or move something gently, especially by a small amount and in a particular direction 轻推；小幅调整
avert: verb (PREVENT) to prevent something bad or dangerous from happening 避免；防止
sliver: noun (THIN PIECE) a small, thin piece cut, split or broken off from something larger 薄片；细条（文中用复数slivers，喻指狭窄的高空冷湿区域）
【长难句】
A British-led consortium unveiled Operation Blue Skies on August 18th—by far the largest trial of contrail avoidance conducted so far—covering Shanwick, a swath of North Atlantic airspace lying west of the British Isles.
主干为"A British-led consortium unveiled Operation Blue Skies on August 18th"，交代"谁、做了什么、何时"； 两个破折号之间"by far the largest trial of contrail avoidance conducted so far"为插入的同位语，对Operation Blue Skies的性质作进一步说明，其中conducted so far为过去分词短语作后置定语，修饰trial； covering Shanwick, a swath of North Atlantic airspace lying west of the British Isles为现在分词短语作伴随状语，交代该项目所涉及的具体空域，其中a swath of North Atlantic airspace为Shanwick的同位语，lying west of the British Isles为现在分词短语作后置定语，修饰airspace。
一个由英国牵头的联合体于8月18日公布了"蓝天行动"——这是迄今规模最大的一次尾迹云规避试验——项目所覆盖的空域是尚维克，即位于不列颠群岛以西的一片北大西洋空域。
【参考译文】
2019年，全球定期航班飞行的总里程约为610亿公里；在超过40%的航程中，飞机身后留下了凝结尾迹（contrails），这是因为废气中的水蒸气凝结成了冰晶。此类尾迹大多会在几分钟内消散。但在较小比例的航程中，周围空气中原本存在的水分也会参与凝结过程，使原本细长的白线扩展成持久存在的卷云状云带。在任何特定时刻，这类人造云层仅覆盖约千分之一的天空，但它们对气候的影响却不容忽视。
原因在于一种微妙的不平衡。凝结尾迹中的冰晶会反射入射的阳光，从而在白天起到冷却地球的作用；但它们也会截留向外散发的红外辐射，并将部分辐射反射回地表——这与温室气体的作用机制类似——而且这种增温效应全天候持续存在。综合来看，增温效应占据了上风：据某些估算，单次飞行留下的凝结尾迹所造成的增温效应，甚至超过了该航班引擎排放的二氧化碳所带来的增温影响。
至关重要的是，这种增温效应并非不可避免。持久性凝结尾迹的形成需要特定条件：周围空气必须足够寒冷，且含有尚未凝结的水分；若没有微粒作为“凝结核”来引发这一过程，这些水分本只会以水蒸气形式存在，而凝结尾迹恰好提供了数以万亿计的此类微粒。这些处于“冰过饱和”状态的区域厚度通常仅数百米，但在水平方向上却可能绵延数百公里。原则上，只要引导飞机避开这些区域，就能消除大部分相关的增温效应。
这一原理目前正接受实际验证。8月18日，一个由英国主导的联盟启动了“蓝天行动”（Operation Blue Skies）——这是迄今为止规模最大的凝结尾迹规避试验——其覆盖区域为“香威克”（Shanwick）空域，即不列颠群岛以西的一片北大西洋空域。选择香威克作为试验场十分理想：该空域巡航高度的空气常年寒冷潮湿，是跨大西洋航班的繁忙通道，且受到欧美气象卫星的全天候监测。尽管该空域仅占地球表面积的0.4%，但模型估算显示，它产生的增温效应约占全球所有凝结尾迹总增温效应的二十分之一。在未来两个冬季总计20到40天的时间里，只要气象条件显示存在形成持久性凝结尾迹的风险，且没有其他因素（如湍流）阻碍，空中交通管制员就会引导选定的航班在比原定高度低几百米的位置飞行。通过对比实施此类调整与未实施调整期间的卫星图像，人们应能可靠地判断这种干预措施是否确实能减少目标区域的卷云覆盖。
相比之下，其成本显得微不足道。虽然在较低高度飞行会多消耗少量燃料，但早期的初步试验发现这种差异几乎难以察觉；一位气候科学家估算，在那些凝结尾迹问题最严重的航线上，因多耗油而额外排放的一吨二氧化碳，或许能避免相当于一百吨二氧化碳排放量的凝结尾迹增温效应。持怀疑态度的人则认为，专注于应对凝结尾迹可能会分散航空公司的注意力，使其偏离减少直接二氧化碳排放这一更艰巨、更漫长的任务。这种担忧不无道理，但这绝非无所作为的理由：与其他大多数气候治理措施不同，避开特定狭窄区域内寒冷潮湿的高空空域既快捷又低廉；一旦试验成功，该方案几乎可以立即推广应用。
附注：