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  3. EARTH’S ENERGY CYCLE (1) To understand most of the processes at work on Earth, it is useful to envisage interactions within

EARTH’S ENERGY CYCLE (1) To understand most of the processes at work on Earth, it is useful to envisage interactions within

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问题                                                 EARTH’S ENERGY CYCLE
    (1) To understand most of the processes at work on Earth, it is useful to envisage interactions within the Earth system as a series of interrelated cycles. One of these is the energy cycle, which encompasses the great "engines"—the external and internal energy sources—that drive the Earth system and all its cycles. We can think of Earth’s energy cycle as a "budget”: energy may be added to or subtracted from the budget and may be transferred from one storage place to another, but overall the additions and subtractions and transfers must balance each other. If a balance did not exist, Earth would either heat up or cool down until a balance was reached.
    (2) The total amount of energy flowing into Earth’s energy budget is more than 174,000 terawatts (or 174,000 x 1012 watts). This quantity completely dwarfs the 10 terawatts of energy that humans use per year. There are three main sources from which energy flows into the Earth system.
    (3) Incoming short-wavelength solar radiation overwhelmingly dominates the flow of energy in Earth’s energy budget, accounting for about 99.986 percent of the total. An estimated 174,000 terawatts of solar radiation is intercepted by Earth. Some of this vast influx powers the winds, rainfall, ocean currents, waves, and other processes in the hydrologic (or water) cycle. Some is used for photosynthesis and is temporarily stored in the biosphere in the form of plant and animal life. When plants die and are buried, some of the solar energy is stored in rocks, when we burn coal, oil, or natural gas, we release stored solar energy.
    (4) The second most powerful source of energy, at 23 terawatts or 0.013 percent of the total, is geothermal energy, Earth’s internal heat energy. Geothermal energy eventually finds its way to Earth’s surface, primarily via volcanic pathways. It drives the rock cycle and is therefore the source of the energy that uplifts mountains, causes earthquakes and volcanic eruptions, and generally shapes the face of the Earth.
    (5) The smallest source of energy for Earth is the kinetic (motion) energy of Earth’s rotation. The Moon’s gravitational pull lifts a tidal bulge in the ocean; as Earth rotates, the tidal bulge runs into the coastlines of continents and islands, causing high tides. The force of the tidal bulge piling up against landmasses acts as a very slow brake, actually causing Earth’s rate of rotation to decrease slightly. The transfer of tidal energy accounts for approximately 3 terawatts, or 0.002 percent of the tidal energy budget.
    (6) Earth loses energy from the cycle in two main ways: reflection, and degradation and reradiation. About 40 percent of incoming solar radiation is simply reflected, unchanged, back into space by the clouds, the sea, and other surfaces. [A] For any planetary body, the percentage of incoming radiation that is reflected is called the "albedo" . [B] Each different material has a characteristic reflectivity. [C] For example, ice is more reflectant than rocks or pavement; water is more highly reflectant than vegetation; and forested land reflects light differently than agricultural land. [D] Thus, if large expanses of land are converted from forest to plowed land, or from forest to city, the actual reflectivity of Earth’s surface, and hence its albedo, may be altered. Any change in albedo will, of course, have an effect on Earth’s energy budget.
    (7) The portion of incoming solar energy that is not reflected back into space, along with tidal and geothermal energy, is absorbed by materials at Earth’s surface, in particular the atmosphere and hydrosphere. This energy undergoes a series of irreversible degradations in which it is transferred from one reservoir to another and converted from one form to another. The energy that is absorbed, utilized, transferred, and degraded eventually ends up as heat, in which form it is reradiated back into space as long-wavelength (infrared) radiation. Weather patterns are a manifestation of energy transfer and degradation.
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.
Earth’s energy cycle consists of all the energy inputs, outputs, and conversions within the Earth system, which must maintain an overall balance.
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Answer Choices
(A) Incoming short-wavelength solar radiation provides Earth with nearly all its energy and powers the hydrologic cycle as well as biological processes.
(B) Heat energy from Earth’s interior, which powers the rock cycle, and the kinetic energy of Earth’s rotation provide small additions to solar energy.
(C) Some of the incoming solar radiation is reflected, and the rest, after being absorbed, undergoes a series of conversions until it is reradiated into space as heat.
(D) Humans use only a small amount of the available solar energy for heat, satisfying most of their energy needs by burning coal, oil, and natural gas.
(E) Solar energy stored in rocks on Earth’s surface is the primary source of geothermal energy and tidal energy.
(F) Earth’s atmosphere and hydrosphere absorb most of the incoming solar radiation, using up much of the energy to power weather patterns, with only the remainder radiated out as heat.
选项
答案A,B,C
解析 本题属于文章总结题。A项“太阳短波入射辐射为地球提供了几乎所有的能量，为水文循环和生物进程提供动力”概括了第3段的内容。B项“来自地球内部的热能为岩石循环运动提供动力，地球自转的动能在太阳能之外提供了少量的补充”概括了第4、5段的大意。C项“一些太阳辐射被反射，其余的在被吸收后，经历了一系列的转化，才作为热的形式再辐射回太空”是对文章第6、7段的概括总结。第3—7段是这篇文章的主旨，也与概要句相符合，故A、B、C三项符合题意。D项“人类只使用少量的太阳能来产生热量，通过燃烧煤、石油和天然气来满足他们大部分的能源需求”、E项“储存在地球表面岩石中的太阳能是地热能和潮汐能的主要来源”和F项“地球的大气圈和水圈吸收了大部分的太阳入射辐射，用掉了大部分的太阳能来催生气候模式，只有剩下的部分以热的形式辐射出去”在原文均没有依据。
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