The Greenhouse Effect on Venus

 

The nitrogen and oxygen gases that make up the bulk of Earth’s atmosphere neither absorb nor emit thermal radiation, energy that is released from hot surfaces as electromagnetic waves. It is the water vapor, carbon dioxide, and some other minor gases present in the atmosphere that absorb some of the thermal radiation leaving the surface, acting as a partial blanket for this radiation and causing the difference between the actual average surface temperature on Earth (about 15°C) and the expected temperature if the atmosphere contained nitrogen and oxygen only (about -6°C). This blanketing is known as the natural greenhouse effect, and the gases are known as greenhouse gases.

Greenhouse effects similar to those on Earth also occur on our planetary neighbors, Mars and Venus. Mars is smaller than Earth and possesses, by Earth’s standards, a very thin atmosphere. A barometer on the surface of Mars would record an atmospheric pressure less than 1 percent of that on Earth. Its atmosphere, which consists almost entirely of carbon dioxide, contributes a small but significant greenhouse effect.

The planet Venus, which can often be seen fairly close to the Sun in the morning or evening sky, has a very different atmosphere from Mars’s. Venus is about the same size as Earth. A barometer for use on Venus would need to survive very hostile conditions and would need to be able to measure a pressure about one hundred times as great as that on Earth. Within Venus’ atmosphere, which consists very largely of carbon dioxide, deep clouds consisting of droplets of almost pure sulphuric acid completely cover the planet and prevent most of the sunlight from reaching the surface. Some Russian space probes that have landed there have recorded what would be dusklike conditions on Earth-only 1 or 2 percent of the sunlight present above the clouds penetrates to the surface. One might suppose, because of the small amount of solar energy available to keep the surface warm, that it would be rather cool; on the contrary, measurements from the same Russian space probes find a temperature there of about 525°C-a dull red heat in fact.

The reason for this very high temperature is the greenhouse effect. Because of the very thick absorbing atmosphere of carbon dioxide, little of the thermal radiation from the surface can get out. The atmosphere acts as such an effective radiation blanket that, although there is not much solar energy to warm the surface, the greenhouse effect amounts to nearly 500°C.

What occurs on Venus is an example of what has been called the “runaway”greenhouse effect. It can be explained by imagining the early history of the Venus atmosphere, which was formed by the release of gases from the interior of the planet. At first the atmosphere would contain a lot of water vapor, a powerful greenhouse gas. The greenhouse effect of the water vapor would cause the temperature at the surface to rise. The increased temperature would lead to more evaporation of water from the surface, causing more atmospheric water vapor, a larger greenhouse effect, and therefore a further increased surface temperature. The process would continue until either the atmosphere became saturated with water vapor or all the available water had evaporated.

A runaway sequence something like this seems to have occurred on Venus. Why, we may ask, has it not happened on Earth, a planet of about the same size as Venus and, so far as is known, of a similar initial chemical composition? The reason is that Venus is closer to the Sun than is Earth; the amount of solar energy per square meter falling on Venus is about twice that falling on Earth. The surface of Venus, when there was no atmosphere, would have started off at a temperature of just over 50C. Throughout the sequence described above for Venus, water on the surface would have been continuously boiling. Because of the high temperature, the atmosphere would never have become saturated with water vapor. Earth, however, would have started at a colder temperature; at each stage of the sequence, it would have arrived at an equilibrium in which the oceans never became hot enough to evaporate.

 

1

The nitrogen and oxygen gases that make up the bulk of Earth’s atmosphere neither absorb nor emit thermal radiation, energy that is released from hot surfaces as electromagnetic waves. It is the water vapor, carbon dioxide, and some other minor gases present in the atmosphere that absorb some of the thermal radiation leaving the surface, acting as a partial blanket for this radiation and causing the difference between the actual average surface temperature on Earth (about 15°C) and the expected temperature if the atmosphere contained nitrogen and oxygen only (about -6°C). This blanketing is known as the natural greenhouse effect, and the gases are known as greenhouse gases.

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.

 

Sentence Simplification Questions句子简化题

 

AEarth’s actual surface temperature differs from its expected temperature when increased atmospheric gases and thermal radiation are present.

BEarth’s average surface temperature is significantly higher than it would be if its atmosphere did not contain gases that prevent thermal radiation from escaping.

CNitrogen and oxygen in the atmosphere account for the difference between the actual and expected surface temperature of Earth.

DWater vapor, carbon dioxide, and other gases are prevented from leaving the atmosphere by a partial blanket of thermal radiation.

2

Greenhouse effects similar to those on Earth also occur on our planetary neighbors, Mars and Venus. Mars is smaller than Earth and possesses, by Earth’s standards, a very thin atmosphere. A barometer on the surface of Mars would record an atmospheric pressure less than 1 percent of that on Earth. Its atmosphere, which consists almost entirely of carbon dioxide, contributes a small but significant greenhouse effect.

According to paragraph 2, all of the following are true of Mars EXCEPT:

 

Negative Factual Information Questions否定事实信息题

 

AIts greenhouse effect is more significant than Earth’s is.

BIts atmosphere consists mainly of carbon dioxide.

CIt has a much lower atmospheric pressure than Earth does.

DIts atmosphere is not as thick as Earth’s atmosphere is.

3

The planet Venus, which can often be seen fairly close to the Sun in the morning or evening sky, has a very different atmosphere from Mars’s. Venus is about the same size as Earth. A barometer for use on Venus would need to survive very hostile conditions and would need to be able to measure a pressure about one hundred times as great as that on Earth. Within Venus’ atmosphere, which consists very largely of carbon dioxide, deep clouds consisting of droplets of almost pure sulphuric acid completely cover the planet and prevent most of the sunlight from reaching the surface. Some Russian space probes that have landed there have recorded what would be dusklike conditions on Earth-only 1 or 2 percent of the sunlight present above the clouds penetrates to the surface. One might suppose, because of the small amount of solar energy available to keep the surface warm, that it would be rather cool; on the contrary, measurements from the same Russian space probes find a temperature there of about 525°C-a dull red heat in fact.

The word “hostile” in the passage is closest in meaning to

 

Vocabulary Questions词汇题

 

Aunexpected

Bspecific

Cunfavorable

Dinconsistent

4

The planet Venus, which can often be seen fairly close to the Sun in the morning or evening sky, has a very different atmosphere from Mars’s. Venus is about the same size as Earth. A barometer for use on Venus would need to survive very hostile conditions and would need to be able to measure a pressure about one hundred times as great as that on Earth. Within Venus’ atmosphere, which consists very largely of carbon dioxide, deep clouds consisting of droplets of almost pure sulphuric acid completely cover the planet and prevent most of the sunlight from reaching the surface. Some Russian space probes that have landed there have recorded what would be dusklike conditions on Earth-only 1 or 2 percent of the sunlight present above the clouds penetrates to the surface. One might suppose, because of the small amount of solar energy available to keep the surface warm, that it would be rather cool; on the contrary, measurements from the same Russian space probes find a temperature there of about 525°C-a dull red heat in fact.

Paragraph 3 supports which of the following statements about the measurement of barometric pressure on Venus?

 

Factual Information Questions事实信息题

 

ABarometric pressure cannot be measured with a standard barometer used to measure Earth’s pressure.

BBarometric pressure is most accurately measured in the morning and evening when Venus is seen close to the Sun.

CIt is difficult to get an accurate measurement of barometric pressure on Venus because of the size of Venus.

DA measurement of barometric pressure on Venus would produce similar results to a measurement of barometric pressure obtained from Mars

5

The planet Venus, which can often be seen fairly close to the Sun in the morning or evening sky, has a very different atmosphere from Mars’s. Venus is about the same size as Earth. A barometer for use on Venus would need to survive very hostile conditions and would need to be able to measure a pressure about one hundred times as great as that on Earth. Within Venus’ atmosphere, which consists very largely of carbon dioxide, deep clouds consisting of droplets of almost pure sulphuric acid completely cover the planet and prevent most of the sunlight from reaching the surface. Some Russian space probes that have landed there have recorded what would be dusklike conditions on Earth-only 1 or 2 percent of the sunlight present above the clouds penetrates to the surface. One might suppose, because of the small amount of solar energy available to keep the surface warm, that it would be rather cool; on the contrary, measurements from the same Russian space probes find a temperature there of about 525°C-a dull red heat in fact.

In paragraph 3, why does the author report the findings of some Russian space probes about light on the surface of Venus?

 

Factual Information Questions事实信息题

 

ATo explain why Venus’ pressure is so much higher than Earth pressure

BTo provide an example of the progress that has been achieved in the study of the surface of Venus

CTo provide evidence that Venus’ atmosphere prevents most sunlight from reaching the surface

DTo support the conclusion that Venus and Earth have similar lighting conditions at dusk

6

The planet Venus, which can often be seen fairly close to the Sun in the morning or evening sky, has a very different atmosphere from Mars’s. Venus is about the same size as Earth. A barometer for use on Venus would need to survive very hostile conditions and would need to be able to measure a pressure about one hundred times as great as that on Earth. Within Venus’ atmosphere, which consists very largely of carbon dioxide, deep clouds consisting of droplets of almost pure sulphuric acid completely cover the planet and prevent most of the sunlight from reaching the surface. Some Russian space probes that have landed there have recorded what would be dusklike conditions on Earth-only 1 or 2 percent of the sunlight present above the clouds penetrates to the surface. One might suppose, because of the small amount of solar energy available to keep the surface warm, that it would be rather cool; on the contrary, measurements from the same Russian space probes find a temperature there of about 525°C-a dull red heat in fact.

The temperature measurements from the Russian space probes are discussed in paragraph 3 as being important because they

 

Factual Information Questions事实信息题

 

Aprovided the first accurate measurement of the temperature on Venus

Bcorrected a possible misconception about the effects of limited sunlight on Venus

Chelped explain the dusk like conditions on Venus

Dprovided evidence that the surface of Venus is hotter than the surfaces of both Earth and Mars

7

What occurs on Venus is an example of what has been called the “runaway”greenhouse effect. It can be explained by imagining the early history of the Venus atmosphere, which was formed by the release of gases from the interior of the planet. At first the atmosphere would contain a lot of water vapor, a powerful greenhouse gas. The greenhouse effect of the water vapor would cause the temperature at the surface to rise. The increased temperature would lead to more evaporation of water from the surface, causing more atmospheric water vapor, a larger greenhouse effect, and therefore a further increased surface temperature. The process would continue until either the atmosphere became saturated with water vapor or all the available water had evaporated.

According to paragraph 5, the runaway greenhouse effect on Venus was probably characterized by all of the following EXCEPT

 

Negative Factual Information Questions否定事实信息题

 

Aan early atmosphere containing large quantities of water vapor

Ba warming of the temperature at the surface of the planet

Can ongoing cycle in which increasing amounts of water became water vapor

Da continuous process of gas entering and leaving the planet’s interior

8

A runaway sequence something like this seems to have occurred on Venus. Why, we may ask, has it not happened on Earth, a planet of about the same size as Venus and, so far as is known, of a similar initial chemical composition? The reason is that Venus is closer to the Sun than is Earth; the amount of solar energy per square meter falling on Venus is about twice that falling on Earth. The surface of Venus, when there was no atmosphere, would have started off at a temperature of just over 50C. Throughout the sequence described above for Venus, water on the surface would have been continuously boiling. Because of the high temperature, the atmosphere would never have become saturated with water vapor. Earth, however, would have started at a colder temperature; at each stage of the sequence, it would have arrived at an equilibrium in which the oceans never became hot enough to evaporate.

According to paragraph 6, why did Earth not experience a runaway greenhouse effect of the kind that occurred on Venus?

 

Factual Information Questions事实信息题

 

AEarth’s early atmosphere became saturated with water vapor.

BThe chemical composition of Earth’s surface protected it from the effects of greenhouse gases.

CEarth’s early surface reflected more solar energy per square meter than did Venus’ surface.

DEarth’s position in relation to the Sun gave it a lower initial temperature

9

What occurs on Venus is an example of what has been called the “runaway”greenhouse effect.  [■]  It can be explained by imagining the early history of the Venus atmosphere, which was formed by the release of gases from the interior of the planet.  [■]  At first the atmosphere would contain a lot of water vapor, a powerful greenhouse gas.  [■]  The greenhouse effect of the water vapor would cause the temperature at the surface to rise. [■]   The increased temperature would lead to more evaporation of water from the surface, causing more atmospheric water vapor, a larger greenhouse effect, and therefore a further increased surface temperature. The process would continue until either the atmosphere became saturated with water vapor or all the available water had evaporated.

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

In general, this means that a chain of events was set in motion, with each event building on the previous one to continually raise temperatures.

Insert Text Questions句子插入题

 

Where would the sentence best fit？Click on a square  sentence to the passage.

10

Venus’s greenhouse effect is greater than that on Mars or Earth.

 

Prose Summary Questions概要小结题

 

Select 3 answers

AThough Venus’s thick atmosphere blocks most sunlight from reaching its surface, it also warms the planet by preventing the escape of thermal radiation.

BIn its early history Venus experienced a runaway greenhouse effect,in which water on the surface was repeatedly heated and continually evaporated into the atmosphere.

CEarth avoided a runaway greenhouse effect like that on Venus because it did not receive enough solar energy for surface water to boil away.

DEarth has a small greenhouse effect in comparison with other planets because there is relatively little thermal radiation leaving Earth’s interior

EA barometer on the surface of Mars could survive better than one on Venus, because Mars’s atmospheric pressure is much lower than that on Venus.

FDuring the early years of its greenhouse effect, Earth-unlike Venus-was able to retain much of its surface water because its atmosphere does not contain large amounts of sulphuric acid.

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