首页
登录
职称英语
Surface Fluids on Venus and EarthP1: When astronomers first pointed their rudim
Surface Fluids on Venus and EarthP1: When astronomers first pointed their rudim
游客
2025-02-05
46
管理
问题
Surface Fluids on Venus and Earth
P1: When astronomers first pointed their rudimentary telescopes at Venus, they saw a world shrouded in clouds. Here on Earth, clouds mean water, so early astronomers imagined a tropical world with constant rainfall. The truth, of course, is that the hydrological state on Venus is quite different from that of Earth. The hydrologic cycle describes the continuous movement of liquid above, on, and below the surface of a planet. These movements derive their energy from the Sun and the gravitational forces of the planet itself, and in turn redistribute energy around the globe through atmospheric circulation. As fluids interact with surface materials, water molecules move particles repeatedly through solid, liquid, and gaseous phases or react chemically with them to modify and produce materials. On a solid planet with a hydrosphere and an atmosphere, only a tiny fraction of the planetary mass flows as surface fluids. Yet, the movements of these fluids can drastically alter a planet.
P2: Imagine Venus a long time ago. The planet is nearly identical to the Earth in size, mass, composition and distance from the Sun. However, it lacks any sign of a hydrologic system—there are no streams, lakes, oceans, or glaciers. It begins like the Earth with global oceans, carbon dioxide dissolved in the oceans, and carbonate rocks forming at the bottoms of the oceans. But because Venus is just a tiny bit smaller than the Earth, it has less radioactive heat sources inside. Thus, at some time in the distant past, perhaps only 500 million to 1 billion years ago, Venus may have run out of enough internal heat to continue to drive the tectonic activity. Alternatively, because Venus is a little closer to the Sun, we would expect that the original temperature of Venus should have been a little warmer than that of the early Earth. The slightly elevated temperature puts a bit more water in the oceans and atmosphere and a bit less in the rocks. This makes the rocks harder since water serves as a lubricant for the plate tectonic process. Either way, tectonic activity begins to slow down. Because Venus receives more heat from the Sun, water released from the interior evaporated and rose to the upper atmosphere, where the Sun’s ultraviolet rays broke the molecules apart. Much of the freed hydrogen escaped into space, and Venus lost its water. Without water, Venus became less and less like Earth and kept an atmosphere filled with carbon dioxide. On Earth, liquid water removes carbon dioxide from the atmosphere and combines it with calcium, through rock weathering, to form carbonate sedimentary rocks. Without liquid water to remove carbon from the atmosphere, prohibiting the formation of carbonate minerals, the level of carbon dioxide in the atmosphere of Venus remains high.
P3: Like Venus, Earth is large enough to be geologically active and for its gravitational field to hold an atmosphere. But fortunately, being further away, it has less heating from the sun and allows water to exist as a liquid, a solid, and a gas. Water is thus extremely mobile and moves rapidly over the planet in a continuous hydrologic cycle. Driven by energy from the sun, water is constantly being cycled from the ocean, through the atmosphere, and ultimately back to the oceans. As a result, Earth’s surface has been continually changed and eroded into delicate systems of river valleys—a remarkable contrast to the surfaces of other planetary bodies where impact craters dominate. Other geologic changes occur when the gases in the atmosphere or water react with rocks at the surface to form new chemical components with different properties. Weathering breaks down rocks into gravel, sand, and sediment, and is an important source of key nutrients such as calcium and sulfur. Estimates indicate that, on average, Earth’s surface weathers at a rate of about 0.5 millimeter per year. Actual rates may be much higher at specific locations and may have been accelerated by human activities. However, none of these would have happened if our planet had spun a little further from or nearer to the sun. Because liquid water was present, self-replicating molecules of carbon, hydrogen, and oxygen developed life early in Earth’s history and have rapidly modified its surface, blanketing huge parts of the continents with greenery.
P2: Imagine Venus a long time ago. The planet is nearly identical to the Earth in size, mass, composition and distance from the Sun. ■ However, it lacks any sign of a hydrologic system—there are no streams, lakes, oceans, or glaciers.■ It begins like the Earth with global oceans, carbon dioxide dissolved in the oceans, and carbonate rocks forming at the bottoms of the oceans. ■But because Venus is just a tiny bit smaller than the Earth, it has less radioactive heat sources inside. Thus, at some time in the distant past, perhaps only 500 million to 1 billion years ago, Venus may have run out of enough internal heat to continue to drive the tectonic activity. Alternatively, because Venus is a little closer to the Sun, we would expect that the original temperature of Venus should have been a little warmer than that of the early Earth. The slightly elevated temperature puts a bit more water in the oceans and atmosphere and a bit less in the rocks. This makes the rocks harder since water serves as a lubricant for the plate tectonic process. Either way, tectonic activity begins to slow down. Because Venus receives more heat from the Sun, water released from the interior evaporated and rose to the upper atmosphere, where the Sun’s ultraviolet rays broke the molecules apart. ■ Much of the freed hydrogen escaped into space, and Venus lost its water. Without water, Venus became less and less like Earth and kept an atmosphere filled with carbon dioxide. On Earth, liquid water removes carbon dioxide from the atmosphere and combines it with calcium, through rock weathering, to form carbonate sedimentary rocks. Without liquid water to remove carbon from the atmosphere, prohibiting the formation of carbonate minerals, the level of carbon dioxide in the atmosphere of Venus remains high. [br] Why does the author point out that on Earth "gases in the atmosphere or water react with rocks at the surface to form new chemical components"?
选项
A、To explain why scientists believe that few areas on Earth have been untouched by flowing water
B、To identify one of several ways in which the movement of fluids can affect the surface of a planet
C、To provide evidence that fluid movements are caused by gravity flow systems energized by the Sun
D、To identify an effect of wind scouring fine particles away from large areas
答案
B
解析
【修辞目的题】当提问内容出现时会产生其他地质变化,说明提问内容是变化的原因之一,答案为B。
转载请注明原文地址:https://tihaiku.com/zcyy/3943346.html
相关试题推荐
SurfaceFluidsonVenusandEarthP1:Whenastronomersfirstpointedtheirrudim
SurfaceFluidsonVenusandEarthP1:Whenastronomersfirstpointedtheirrudim
SurfaceFluidsonVenusandEarthP1:Whenastronomersfirstpointedtheirrudim
SurfaceFluidsonVenusandEarthP1:Whenastronomersfirstpointedtheirrudim
SurfaceFluidsonVenusandEarthP1:Whenastronomersfirstpointedtheirrudim
SurfaceFluidsonVenusandEarthP1:Whenastronomersfirstpointedtheirrudim
SurfaceFluidsonVenusandEarthP1:Whenastronomersfirstpointedtheirrudim
SurfaceFluidsonVenusandEarthP1:Whenastronomersfirstpointedtheirrudim
Thehard,outsurfaceofthetoothiscalledenamel.A、outsideB、appearanceC、out
ThedenseBelgianfogsiscausedbythecoolingofhumidsurfaceairtoarelati
随机试题
[originaltext]M:IhadprepareddinnerforeightpeoplebeforeMarycalledand
[originaltext]W:Ohdear,Igainedthese10poundsinthelast3months,noneo
钻孔灌注桩根据施工机械的不同,分为()。A.冲击钻成孔 B.正循环钻成孔
A.截石位3、7、11点 B.截石位3、9点 C.截石位6、12点 D.截
连续监测法测定ALT活性浓度,标本量(v)10μl,试剂量350μl,比色杯光径
违反《地图管理条例》,互联网地图服务单位使用未经依法审核批准的地图提供服务,或者
风电场的机型选择非常重要,可根据当地的风况选择适当容量的风力发电机型。从经济效益
县人民政府组织编制的总体规划,在报上一级人民政府审批时,应当首先报本级人民代表大
(2017年真题)下列关于质押和抵押区别的说法中,不正确的是()。A.抵押
(2017年真题)某银行从业人员由于不理解某理财产品的收益率计算,导致宣传该理财
最新回复
(
0
)